[ovs-dev,PATCHv11,2/2] ofp-actions: Add truncate action.

The patch adds a new action to support packet truncation.  The new action
is formatted as 'output(port=n,max_len=m)', as output to port n, with
packet size being MIN(original_size, m).

One use case is to enable port mirroring to send smaller packets to the
destination port so that only useful packet information is mirrored/copied,
saving some performance overhead of copying entire packet payload.  Example
use case is below as well as shown in the testcases:

    - Output to port 1 with max_len 100 bytes.
    - The output packet size on port 1 will be MIN(original_packet_size, 100).
    # ovs-ofctl add-flow br0 'actions=output(port=1,max_len=100)'

    - The scope of max_len is limited to output action itself.  The following
      packet size of output:1 and output:2 will be intact.
    # ovs-ofctl add-flow br0 \
            'actions=output(port=1,max_len=100),output:1,output:2'
    - The Datapath actions shows:
    # Datapath actions: trunc(100),1,1,2

Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/139668398
Signed-off-by: William Tu <u9012063@gmail.com>
---
 include/openvswitch/ofp-actions.h |  10 ++
 lib/dp-packet.c                   |   2 +
 lib/dp-packet.h                   |  67 +++++++++++
 lib/dpif-netdev.c                 |  33 ++++-
 lib/dpif.c                        |  25 +++-
 lib/dpif.h                        |   1 +
 lib/netdev-bsd.c                  |   3 +
 lib/netdev-dpdk.c                 |  21 ++++
 lib/netdev-dummy.c                |   2 +
 lib/netdev-linux.c                |   3 +
 lib/netdev.c                      |   5 +-
 lib/odp-execute.c                 |  12 ++
 lib/odp-util.c                    |  23 ++++
 lib/ofp-actions.c                 | 106 ++++++++++++++++
 ofproto/ofproto-dpif-sflow.c      |   1 +
 ofproto/ofproto-dpif-xlate.c      |  57 +++++++++
 ofproto/ofproto-dpif.c            |  79 ++++++++++++
 ofproto/ofproto-dpif.h            |   3 +
 tests/odp.at                      |   1 +
 tests/ofp-actions.at              |   3 +
 tests/ofproto-dpif.at             | 124 +++++++++++++++++++
 tests/ovs-ofctl.at                |   8 ++
 tests/system-kmod-macros.at       |   7 ++
 tests/system-traffic.at           | 247 ++++++++++++++++++++++++++++++++++++++
 tests/system-userspace-macros.at  |   7 ++
 25 files changed, 846 insertions(+), 4 deletions(-)

On Wed, Jun 22, 2016 at 10:02 PM, William Tu <u9012063@gmail.com> wrote:
> The patch adds a new action to support packet truncation.  The new action
> is formatted as 'output(port=n,max_len=m)', as output to port n, with
> packet size being MIN(original_size, m).
>
> One use case is to enable port mirroring to send smaller packets to the
> destination port so that only useful packet information is mirrored/copied,
> saving some performance overhead of copying entire packet payload.  Example
> use case is below as well as shown in the testcases:
>
>     - Output to port 1 with max_len 100 bytes.
>     - The output packet size on port 1 will be MIN(original_packet_size, 100).
>     # ovs-ofctl add-flow br0 'actions=output(port=1,max_len=100)'
>
>     - The scope of max_len is limited to output action itself.  The following
>       packet size of output:1 and output:2 will be intact.
>     # ovs-ofctl add-flow br0 \
>             'actions=output(port=1,max_len=100),output:1,output:2'
>     - The Datapath actions shows:
>     # Datapath actions: trunc(100),1,1,2
>
> Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/139668398
> Signed-off-by: William Tu <u9012063@gmail.com>
> ---
>  include/openvswitch/ofp-actions.h |  10 ++
>  lib/dp-packet.c                   |   2 +
>  lib/dp-packet.h                   |  67 +++++++++++
>  lib/dpif-netdev.c                 |  33 ++++-
>  lib/dpif.c                        |  25 +++-
>  lib/dpif.h                        |   1 +
>  lib/netdev-bsd.c                  |   3 +
>  lib/netdev-dpdk.c                 |  21 ++++
>  lib/netdev-dummy.c                |   2 +
>  lib/netdev-linux.c                |   3 +
>  lib/netdev.c                      |   5 +-
>  lib/odp-execute.c                 |  12 ++
>  lib/odp-util.c                    |  23 ++++
>  lib/ofp-actions.c                 | 106 ++++++++++++++++
>  ofproto/ofproto-dpif-sflow.c      |   1 +
>  ofproto/ofproto-dpif-xlate.c      |  57 +++++++++
>  ofproto/ofproto-dpif.c            |  79 ++++++++++++
>  ofproto/ofproto-dpif.h            |   3 +
>  tests/odp.at                      |   1 +
>  tests/ofp-actions.at              |   3 +
>  tests/ofproto-dpif.at             | 124 +++++++++++++++++++
>  tests/ovs-ofctl.at                |   8 ++
>  tests/system-kmod-macros.at       |   7 ++
>  tests/system-traffic.at           | 247 ++++++++++++++++++++++++++++++++++++++
>  tests/system-userspace-macros.at  |   7 ++
>  25 files changed, 846 insertions(+), 4 deletions(-)
>
> diff --git a/include/openvswitch/ofp-actions.h b/include/openvswitch/ofp-actions.h
> index 91c7ee5..0b8ccbb 100644
> --- a/include/openvswitch/ofp-actions.h
> +++ b/include/openvswitch/ofp-actions.h
> @@ -108,6 +108,7 @@
>      OFPACT(UNROLL_XLATE,    ofpact_unroll_xlate, ofpact, "unroll_xlate") \
>      OFPACT(CT,              ofpact_conntrack,   ofpact, "ct")           \
>      OFPACT(NAT,             ofpact_nat,         ofpact, "nat")          \
> +    OFPACT(OUTPUT_TRUNC,    ofpact_output_trunc,ofpact, "output_trunc") \
>                                                                          \
>      /* Debugging actions.                                               \
>       *                                                                  \
> @@ -290,6 +291,15 @@ struct ofpact_output_reg {
>      struct mf_subfield src;
>  };
>
> +/* OFPACT_OUTPUT_TRUNC.
> + *
> + * Used for NXAST_OUTPUT_TRUNC. */
> +struct ofpact_output_trunc {
> +    struct ofpact ofpact;
> +    ofp_port_t port;            /* Output port. */
> +    uint32_t max_len;           /* Max send len. */
> +};
> +
>  /* Bundle slave choice algorithm to apply.
>   *
>   * In the descriptions below, 'slaves' is the list of possible slaves in the
> diff --git a/lib/dp-packet.c b/lib/dp-packet.c
> index 0c85d50..8e7defc 100644
> --- a/lib/dp-packet.c
> +++ b/lib/dp-packet.c
> @@ -30,6 +30,7 @@ dp_packet_init__(struct dp_packet *b, size_t allocated, enum dp_packet_source so
>      dp_packet_reset_offsets(b);
>      pkt_metadata_init(&b->md, 0);
>      dp_packet_rss_invalidate(b);
> +    dp_packet_reset_cutlen(b);
>  }
>
>  static void
> @@ -168,6 +169,7 @@ dp_packet_clone_with_headroom(const struct dp_packet *buffer, size_t headroom)
>      new_buffer->l3_ofs = buffer->l3_ofs;
>      new_buffer->l4_ofs = buffer->l4_ofs;
>      new_buffer->md = buffer->md;
> +    new_buffer->cutlen = buffer->cutlen;
>  #ifdef DPDK_NETDEV
>      new_buffer->mbuf.ol_flags = buffer->mbuf.ol_flags;
>  #else
> diff --git a/lib/dp-packet.h b/lib/dp-packet.h
> index 118c84d..f505fa5 100644
> --- a/lib/dp-packet.h
> +++ b/lib/dp-packet.h
> @@ -60,6 +60,7 @@ struct dp_packet {
>                                      * or UINT16_MAX. */
>      uint16_t l4_ofs;               /* Transport-level header offset,
>                                        or UINT16_MAX. */
> +    uint32_t cutlen;               /* length in bytes to cut from the end. */
>      union {
>          struct pkt_metadata md;
>          uint64_t data[DP_PACKET_CONTEXT_SIZE / 8];
> @@ -494,6 +495,34 @@ dp_packet_set_allocated(struct dp_packet *b, uint16_t s)
>  }
>  #endif
>
> +static inline void
> +dp_packet_reset_cutlen(struct dp_packet *b)
> +{
> +    b->cutlen = 0;
> +}
> +
> +static inline uint32_t
> +dp_packet_set_cutlen(struct dp_packet *b, uint32_t max_len)
> +{
> +    if (max_len < ETH_HEADER_LEN) {
> +        max_len = ETH_HEADER_LEN;
> +    }
> +
> +    if (max_len >= dp_packet_size(b)) {
> +        b->cutlen = 0;
> +    } else {
> +        b->cutlen = dp_packet_size(b) - max_len;
> +    }
> +    return b->cutlen;
> +}
> +
> +static inline uint32_t
> +dp_packet_get_cutlen(struct dp_packet *b)
> +{
> +    /* Always in valid range if user uses dp_packet_set_cutlen. */
> +    return b->cutlen;
> +}
> +
>  static inline void *
>  dp_packet_data(const struct dp_packet *b)
>  {
> @@ -567,12 +596,14 @@ enum { NETDEV_MAX_BURST = 32 }; /* Maximum number packets in a batch. */
>
>  struct dp_packet_batch {
>      int count;
> +    bool trunc; /* true if the batch needs truncate. */
>      struct dp_packet *packets[NETDEV_MAX_BURST];
>  };
>
>  static inline void dp_packet_batch_init(struct dp_packet_batch *b)
>  {
>      b->count = 0;
> +    b->trunc = false;
>  }
>
>  static inline void
> @@ -585,12 +616,14 @@ dp_packet_batch_clone(struct dp_packet_batch *dst,
>          dst->packets[i] = dp_packet_clone(src->packets[i]);
>      }
>      dst->count = src->count;
> +    dst->trunc = src->trunc;
>  }
>
>  static inline void
>  packet_batch_init_packet(struct dp_packet_batch *b, struct dp_packet *p)
>  {
>      b->count = 1;
> +    b->trunc = false;
>      b->packets[0] = p;
>  }
>
> @@ -606,6 +639,40 @@ dp_packet_delete_batch(struct dp_packet_batch *batch, bool may_steal)
>      }
>  }
>
> +static inline void
> +dp_packet_batch_apply_cutlen(struct dp_packet_batch *pktb)
> +{
> +    int i;
> +
> +    if (!pktb->trunc)
> +        return;
> +
> +    for (i = 0; i < pktb->count; i++) {
> +        uint32_t cutlen = dp_packet_get_cutlen(pktb->packets[i]);
> +
> +        if (cutlen > 0) {
> +            dp_packet_set_size(pktb->packets[i],
> +                dp_packet_size(pktb->packets[i]) - cutlen);
> +            dp_packet_reset_cutlen(pktb->packets[i]);
> +        }
> +    }
> +    pktb->trunc = false;
> +}
> +
> +static inline void
> +dp_packet_batch_reset_cutlen(struct dp_packet_batch *pktb)
> +{
> +    int i;
> +
> +    if (!pktb->trunc)
> +        return;
> +
> +    pktb->trunc = false;
> +    for (i = 0; i < pktb->count; i++) {
> +        dp_packet_reset_cutlen(pktb->packets[i]);
> +    }
> +}
> +
>  #ifdef  __cplusplus
>  }
>  #endif
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 8d39d9e..70f320d 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -4057,13 +4057,17 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>      case OVS_ACTION_ATTR_TUNNEL_PUSH:
>          if (*depth < MAX_RECIRC_DEPTH) {
>              struct dp_packet_batch tnl_pkt;
> +            struct dp_packet_batch *orig_packets_ = packets_;
>              int err;
>
>              if (!may_steal) {
>                  dp_packet_batch_clone(&tnl_pkt, packets_);
>                  packets_ = &tnl_pkt;
> +                dp_packet_batch_reset_cutlen(orig_packets_);
>              }
>
> +            dp_packet_batch_apply_cutlen(packets_);
> +
>              err = push_tnl_action(pmd, a, packets_);
>              if (!err) {
>                  (*depth)++;
> @@ -4076,6 +4080,7 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>
>      case OVS_ACTION_ATTR_TUNNEL_POP:
>          if (*depth < MAX_RECIRC_DEPTH) {
> +            struct dp_packet_batch *orig_packets_ = packets_;
>              odp_port_t portno = u32_to_odp(nl_attr_get_u32(a));
>
>              p = pmd_tx_port_cache_lookup(pmd, portno);
> @@ -4084,10 +4089,13 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>                  int i;
>
>                  if (!may_steal) {
> -                   dp_packet_batch_clone(&tnl_pkt, packets_);
> -                   packets_ = &tnl_pkt;
> +                    dp_packet_batch_clone(&tnl_pkt, packets_);
> +                    packets_ = &tnl_pkt;
> +                    dp_packet_batch_reset_cutlen(orig_packets_);
>                  }
>
> +                dp_packet_batch_apply_cutlen(packets_);
> +
>                  netdev_pop_header(p->netdev, packets_);
>                  if (!packets_->count) {
>                      return;
> @@ -4107,22 +4115,42 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>
>      case OVS_ACTION_ATTR_USERSPACE:
>          if (!fat_rwlock_tryrdlock(&dp->upcall_rwlock)) {
> +            struct dp_packet_batch *orig_packets_ = packets_;
>              struct dp_packet **packets = packets_->packets;
>              const struct nlattr *userdata;
> +            struct dp_packet_batch usr_pkt;
>              struct ofpbuf actions;
>              struct flow flow;
>              ovs_u128 ufid;
> +            bool clone = false;
>              int i;
>
>              userdata = nl_attr_find_nested(a, OVS_USERSPACE_ATTR_USERDATA);
>              ofpbuf_init(&actions, 0);
>
> +            if (packets_->trunc) {
> +                if (!may_steal) {
> +                    dp_packet_batch_clone(&usr_pkt, packets_);
> +                    packets_ = &usr_pkt;
> +                    packets = packets_->packets;
> +                    clone = true;
> +                    dp_packet_batch_reset_cutlen(orig_packets_);
> +                }
> +
> +                dp_packet_batch_apply_cutlen(packets_);
> +            }
> +
>              for (i = 0; i < packets_->count; i++) {
>                  flow_extract(packets[i], &flow);
>                  dpif_flow_hash(dp->dpif, &flow, sizeof flow, &ufid);
>                  dp_execute_userspace_action(pmd, packets[i], may_steal, &flow,
>                                              &ufid, &actions, userdata);
>              }
> +
> +            if (clone) {
> +                dp_packet_delete_batch(packets_, true);
> +            }
> +
>              ofpbuf_uninit(&actions);
>              fat_rwlock_unlock(&dp->upcall_rwlock);
>
> @@ -4170,6 +4198,7 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>      case OVS_ACTION_ATTR_SAMPLE:
>      case OVS_ACTION_ATTR_HASH:
>      case OVS_ACTION_ATTR_UNSPEC:
> +    case OVS_ACTION_ATTR_TRUNC:
>      case __OVS_ACTION_ATTR_MAX:
>          OVS_NOT_REACHED();
>      }
> diff --git a/lib/dpif.c b/lib/dpif.c
> index c4f24c7..5f1be41 100644
> --- a/lib/dpif.c
> +++ b/lib/dpif.c
> @@ -1092,6 +1092,7 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>      struct dpif_execute_helper_aux *aux = aux_;
>      int type = nl_attr_type(action);
>      struct dp_packet *packet = packets_->packets[0];
> +    struct dp_packet *trunc_packet = NULL, *orig_packet;
>
>      ovs_assert(packets_->count == 1);
>
> @@ -1106,7 +1107,8 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>          struct ofpbuf execute_actions;
>          uint64_t stub[256 / 8];
>          struct pkt_metadata *md = &packet->md;
> -        bool dst_set;
> +        bool dst_set, clone = false;
> +        uint32_t cutlen = dp_packet_get_cutlen(packet);
>
>          dst_set = flow_tnl_dst_is_set(&md->tunnel);
>          if (dst_set) {
> @@ -1124,6 +1126,22 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>              execute.actions_len = NLA_ALIGN(action->nla_len);
>          }
>
> +        orig_packet = packet;
> +
> +        if (cutlen > 0 && (type == OVS_ACTION_ATTR_OUTPUT ||
> +            type == OVS_ACTION_ATTR_TUNNEL_PUSH ||
> +            type == OVS_ACTION_ATTR_TUNNEL_POP ||
> +            type == OVS_ACTION_ATTR_USERSPACE)) {
> +            if (!may_steal) {
> +                trunc_packet = dp_packet_clone(packet);
> +                packet = trunc_packet;
> +                clone = true;
> +            }
> +
> +            dp_packet_set_size(packet, dp_packet_size(packet) - cutlen);
> +            dp_packet_reset_cutlen(orig_packet);
> +        }
> +
>          execute.packet = packet;
>          execute.flow = aux->flow;
>          execute.needs_help = false;
> @@ -1135,6 +1153,10 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>          if (dst_set) {
>              ofpbuf_uninit(&execute_actions);
>          }
> +
> +        if (clone) {
> +            dp_packet_delete(trunc_packet);
> +        }
>          break;
>      }
>
> @@ -1146,6 +1168,7 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>      case OVS_ACTION_ATTR_SET:
>      case OVS_ACTION_ATTR_SET_MASKED:
>      case OVS_ACTION_ATTR_SAMPLE:
> +    case OVS_ACTION_ATTR_TRUNC:
>      case OVS_ACTION_ATTR_UNSPEC:
>      case __OVS_ACTION_ATTR_MAX:
>          OVS_NOT_REACHED();
> diff --git a/lib/dpif.h b/lib/dpif.h
> index 6788301..981868c 100644
> --- a/lib/dpif.h
> +++ b/lib/dpif.h
> @@ -784,6 +784,7 @@ struct dpif_upcall {
>      size_t key_len;             /* Length of 'key' in bytes. */
>      ovs_u128 ufid;              /* Unique flow identifier for 'key'. */
>      struct nlattr *mru;         /* Maximum receive unit. */
> +    struct nlattr *cutlen;      /* Number of bytes shrink from the end. */
>
>      /* DPIF_UC_ACTION only. */
>      struct nlattr *userdata;    /* Argument to OVS_ACTION_ATTR_USERSPACE. */
> diff --git a/lib/netdev-bsd.c b/lib/netdev-bsd.c
> index 43fa982..2e92d97 100644
> --- a/lib/netdev-bsd.c
> +++ b/lib/netdev-bsd.c
> @@ -699,6 +699,9 @@ netdev_bsd_send(struct netdev *netdev_, int qid OVS_UNUSED,
>          const void *data = dp_packet_data(pkts[i]);
>          size_t size = dp_packet_size(pkts[i]);
>
> +        /* Truncate the packet if it is configured. */
> +        size -= dp_packet_get_cutlen(pkts[i]);
> +
>          while (!error) {
>              ssize_t retval;
>              if (dev->tap_fd >= 0) {
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index fc0c8d3..8063add 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -1487,6 +1487,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts,
>
>      for (i = 0; i < cnt; i++) {
>          int size = dp_packet_size(pkts[i]);
> +        int cutlen = dp_packet_get_cutlen(pkts[i]);
>
>          if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>              VLOG_WARN_RL(&rl, "Too big size %d max_packet_len %d",
> @@ -1503,6 +1504,12 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts,
>              break;
>          }
>
> +        if (OVS_UNLIKELY(cutlen > 0)) {
> +            /* Cut the size so only the truncated size is copied. */
> +            size -= cutlen;
> +            dp_packet_reset_cutlen(pkts[i]);
> +        }
> +
As commented in last review, there is no need to check for cut length
anywhere while setting the size.

>          /* We have to do a copy for now */
>          memcpy(rte_pktmbuf_mtod(mbufs[newcnt], void *), dp_packet_data(pkts[i]), size);
>
> @@ -1550,6 +1557,14 @@ netdev_dpdk_vhost_send(struct netdev *netdev, int qid, struct dp_packet **pkts,
>              }
>          }
>      } else {
> +        int i;
> +
> +        for (i = 0; i < cnt; i++) {
> +            int cutlen = dp_packet_get_cutlen(pkts[i]);
> +
> +            dp_packet_set_size(pkts[i], dp_packet_size(pkts[i]) - cutlen);
> +            dp_packet_reset_cutlen(pkts[i]);
> +        }
>          __netdev_dpdk_vhost_send(netdev, qid, pkts, cnt, may_steal);
>      }
>      return 0;
> @@ -1585,6 +1600,12 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid,
>
>          for (i = 0; i < cnt; i++) {
>              int size = dp_packet_size(pkts[i]);
> +            uint32_t cutlen = dp_packet_get_cutlen(pkts[i]);
> +
> +            if (OVS_UNLIKELY(cutlen > 0)) {
> +                size -= cutlen;
> +                dp_packet_set_size(pkts[i], size);
> +            }
>
>              if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>                  if (next_tx_idx != i) {
> diff --git a/lib/netdev-dummy.c b/lib/netdev-dummy.c
> index aa244b6..127b6ae 100644
> --- a/lib/netdev-dummy.c
> +++ b/lib/netdev-dummy.c
> @@ -1044,6 +1044,8 @@ netdev_dummy_send(struct netdev *netdev, int qid OVS_UNUSED,
>          const void *buffer = dp_packet_data(pkts[i]);
>          size_t size = dp_packet_size(pkts[i]);
>
> +        size -= dp_packet_get_cutlen(pkts[i]);
> +
>          if (size < ETH_HEADER_LEN) {
>              error = EMSGSIZE;
>              break;
> diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
> index 82813ba..d6e5a54 100644
> --- a/lib/netdev-linux.c
> +++ b/lib/netdev-linux.c
> @@ -1170,6 +1170,9 @@ netdev_linux_send(struct netdev *netdev_, int qid OVS_UNUSED,
>          size_t size = dp_packet_size(pkts[i]);
>          ssize_t retval;
>
> +        /* Truncate the packet if it is configured. */
> +        size -= dp_packet_get_cutlen(pkts[i]);
> +
>          if (!is_tap_netdev(netdev_)) {
>              /* Use our AF_PACKET socket to send to this device. */
>              struct sockaddr_ll sll;
> diff --git a/lib/netdev.c b/lib/netdev.c
> index 4be806d..6651173 100644
> --- a/lib/netdev.c
> +++ b/lib/netdev.c
> @@ -681,7 +681,7 @@ netdev_set_tx_multiq(struct netdev *netdev, unsigned int n_txq)
>      return error;
>  }
>
> -/* Sends 'buffers' on 'netdev'.  Returns 0 if successful (for every packet),
> +/* Sends 'batch' on 'netdev'.  Returns 0 if successful (for every packet),
>   * otherwise a positive errno value.  Returns EAGAIN without blocking if
>   * at least one the packets cannot be queued immediately.  Returns EMSGSIZE
>   * if a partial packet was transmitted or if a packet is too big or too small
> @@ -716,6 +716,9 @@ netdev_send(struct netdev *netdev, int qid, struct dp_packet_batch *batch,
>                                             may_steal);
>      if (!error) {
>          COVERAGE_INC(netdev_sent);
> +        if (!may_steal) {
> +            dp_packet_batch_reset_cutlen(batch);
> +        }
>      }
>      return error;
>  }
> diff --git a/lib/odp-execute.c b/lib/odp-execute.c
> index 4239624..5a43904 100644
> --- a/lib/odp-execute.c
> +++ b/lib/odp-execute.c
> @@ -503,6 +503,7 @@ requires_datapath_assistance(const struct nlattr *a)
>      case OVS_ACTION_ATTR_HASH:
>      case OVS_ACTION_ATTR_PUSH_MPLS:
>      case OVS_ACTION_ATTR_POP_MPLS:
> +    case OVS_ACTION_ATTR_TRUNC:
>          return false;
>
>      case OVS_ACTION_ATTR_UNSPEC:
> @@ -625,6 +626,17 @@ odp_execute_actions(void *dp, struct dp_packet_batch *batch, bool steal,
>              }
>              break;
>
> +        case OVS_ACTION_ATTR_TRUNC: {
> +            const struct ovs_action_trunc *trunc =
> +                        nl_attr_get_unspec(a, sizeof *trunc);
> +
> +            batch->trunc = true;
> +            for (i = 0; i < cnt; i++) {
> +                dp_packet_set_cutlen(packets[i], trunc->max_len);
> +            }
> +            break;
> +        }
> +
>          case OVS_ACTION_ATTR_OUTPUT:
>          case OVS_ACTION_ATTR_TUNNEL_PUSH:
>          case OVS_ACTION_ATTR_TUNNEL_POP:
> diff --git a/lib/odp-util.c b/lib/odp-util.c
> index 48c05f5..d7b6a2d 100644
> --- a/lib/odp-util.c
> +++ b/lib/odp-util.c
> @@ -107,6 +107,7 @@ odp_action_len(uint16_t type)
>
>      switch ((enum ovs_action_attr) type) {
>      case OVS_ACTION_ATTR_OUTPUT: return sizeof(uint32_t);
> +    case OVS_ACTION_ATTR_TRUNC: return sizeof(struct ovs_action_trunc);
>      case OVS_ACTION_ATTR_TUNNEL_PUSH: return ATTR_LEN_VARIABLE;
>      case OVS_ACTION_ATTR_TUNNEL_POP: return sizeof(uint32_t);
>      case OVS_ACTION_ATTR_USERSPACE: return ATTR_LEN_VARIABLE;
> @@ -777,6 +778,14 @@ format_odp_action(struct ds *ds, const struct nlattr *a)
>      case OVS_ACTION_ATTR_OUTPUT:
>          ds_put_format(ds, "%"PRIu32, nl_attr_get_u32(a));
>          break;
> +    case OVS_ACTION_ATTR_TRUNC: {
> +        const struct ovs_action_trunc *trunc =
> +                       nl_attr_get_unspec(a, sizeof *trunc);
> +
> +        ds_put_format(ds, "trunc(%"PRIu32")", trunc->max_len);
> +        break;
> +    }
> +    break;
>      case OVS_ACTION_ATTR_TUNNEL_POP:
>          ds_put_format(ds, "tnl_pop(%"PRIu32")", nl_attr_get_u32(a));
>          break;
> @@ -1528,6 +1537,20 @@ parse_odp_action(const char *s, const struct simap *port_names,
>          }
>      }
>
> +    {
> +        uint32_t max_len;
> +        int n;
> +
> +        if (ovs_scan(s, "trunc(%"SCNi32")%n", &max_len, &n)) {
> +            struct ovs_action_trunc *trunc;
> +
> +            trunc = nl_msg_put_unspec_uninit(actions,
> +                     OVS_ACTION_ATTR_TRUNC, sizeof *trunc);
> +            trunc->max_len = max_len;
> +            return n;
> +        }
> +    }
> +
>      if (port_names) {
>          int len = strcspn(s, delimiters);
>          struct simap_node *node;
> diff --git a/lib/ofp-actions.c b/lib/ofp-actions.c
> index ea55896..997cc15 100644
> --- a/lib/ofp-actions.c
> +++ b/lib/ofp-actions.c
> @@ -301,6 +301,9 @@ enum ofp_raw_action_type {
>      /* NX1.0+(36): struct nx_action_nat, ... */
>      NXAST_RAW_NAT,
>
> +    /* NX1.0+(39): struct nx_action_output_trunc. */
> +    NXAST_RAW_OUTPUT_TRUNC,
> +
>  /* ## ------------------ ## */
>  /* ## Debugging actions. ## */
>  /* ## ------------------ ## */
> @@ -381,6 +384,7 @@ ofpact_next_flattened(const struct ofpact *ofpact)
>      case OFPACT_CONTROLLER:
>      case OFPACT_ENQUEUE:
>      case OFPACT_OUTPUT_REG:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_BUNDLE:
>      case OFPACT_SET_FIELD:
>      case OFPACT_SET_VLAN_VID:
> @@ -538,6 +542,40 @@ encode_OUTPUT(const struct ofpact_output *output,
>  }
>
>  static char * OVS_WARN_UNUSED_RESULT
> +parse_truncate_subfield(struct ofpact_output_trunc *output_trunc,
> +                        const char *arg_)
> +{
> +    char *key, *value;
> +    char *arg = CONST_CAST(char *, arg_);
> +
> +    while (ofputil_parse_key_value(&arg, &key, &value)) {
> +        if (!strcmp(key, "port")) {
> +            if (!ofputil_port_from_string(value, &output_trunc->port)) {
> +                return xasprintf("output to unknown truncate port: %s",
> +                                  value);
> +            }
> +            if (ofp_to_u16(output_trunc->port) > ofp_to_u16(OFPP_MAX)) {
> +                if (output_trunc->port != OFPP_LOCAL &&
> +                    output_trunc->port != OFPP_IN_PORT)
> +                return xasprintf("output to unsupported truncate port: %s",
> +                                 value);
> +            }
> +        } else if (!strcmp(key, "max_len")) {
> +            char *err;
> +
> +            err = str_to_u32(value, &output_trunc->max_len);
> +            if (err) {
> +                return err;
> +            }
> +        } else {
> +            return xasprintf("invalid key '%s' in output_trunc argument",
> +                                key);
> +        }
> +    }
> +    return NULL;
> +}
> +
> +static char * OVS_WARN_UNUSED_RESULT
>  parse_OUTPUT(const char *arg, struct ofpbuf *ofpacts,
>               enum ofputil_protocol *usable_protocols OVS_UNUSED)
>  {
> @@ -547,6 +585,11 @@ parse_OUTPUT(const char *arg, struct ofpbuf *ofpacts,
>          output_reg = ofpact_put_OUTPUT_REG(ofpacts);
>          output_reg->max_len = UINT16_MAX;
>          return mf_parse_subfield(&output_reg->src, arg);
> +    } else if (strstr(arg, "port") && strstr(arg, "max_len")) {
> +        struct ofpact_output_trunc *output_trunc;
> +
> +        output_trunc = ofpact_put_OUTPUT_TRUNC(ofpacts);
> +        return parse_truncate_subfield(output_trunc, arg);
>      } else {
>          struct ofpact_output *output;
>
> @@ -5603,6 +5646,61 @@ parse_NAT(char *arg, struct ofpbuf *ofpacts,
>      return NULL;
>  }
>
> +/* Truncate output action. */
> +struct nx_action_output_trunc {
> +    ovs_be16 type;              /* OFPAT_VENDOR. */
> +    ovs_be16 len;               /* At least 16. */
> +    ovs_be32 vendor;            /* NX_VENDOR_ID. */
> +    ovs_be16 subtype;           /* NXAST_OUTPUT_TRUNC. */
> +    ovs_be16 port;              /* Output port */
> +    ovs_be32 max_len;           /* Truncate packet to size bytes */
> +};
> +OFP_ASSERT(sizeof(struct nx_action_output_trunc) == 16);
> +
> +static enum ofperr
> +decode_NXAST_RAW_OUTPUT_TRUNC(const struct nx_action_output_trunc *natrc,
> +                            enum ofp_version ofp_version OVS_UNUSED,
> +                            struct ofpbuf *out)
> +{
> +    struct ofpact_output_trunc *output_trunc;
> +
> +    output_trunc = ofpact_put_OUTPUT_TRUNC(out);
> +    output_trunc->max_len = ntohl(natrc->max_len);
> +    output_trunc->port = u16_to_ofp(ntohs(natrc->port));
> +
> +    if (output_trunc->max_len < ETH_HEADER_LEN) {
> +        return OFPERR_OFPBAC_BAD_ARGUMENT;
> +    }
> +    return 0;
> +}
> +
> +static void
> +encode_OUTPUT_TRUNC(const struct ofpact_output_trunc *output_trunc,
> +                  enum ofp_version ofp_version OVS_UNUSED,
> +                  struct ofpbuf *out)
> +{
> +    struct nx_action_output_trunc *natrc = put_NXAST_OUTPUT_TRUNC(out);
> +
> +    natrc->max_len = htonl(output_trunc->max_len);
> +    natrc->port = htons(ofp_to_u16(output_trunc->port));
> +}
> +
> +static char * OVS_WARN_UNUSED_RESULT
> +parse_OUTPUT_TRUNC(const char *arg, struct ofpbuf *ofpacts OVS_UNUSED,
> +                 enum ofputil_protocol *usable_protocols OVS_UNUSED)
> +{
> +    /* Disable output_trunc parsing.  Expose as output(port=N,max_len=M) and
> +     * reuse parse_OUTPUT to parse output_trunc action. */
> +    return xasprintf("unknown action %s", arg);
> +}
> +
> +static void
> +format_OUTPUT_TRUNC(const struct ofpact_output_trunc *a, struct ds *s)
> +{
> +     ds_put_format(s, "%soutput%s(port=%"PRIu16",max_len=%"PRIu32")",
> +                   colors.special, colors.end, a->port, a->max_len);
> +}
> +
>
>  /* Meter instruction. */
>
> @@ -5997,6 +6095,7 @@ ofpact_is_set_or_move_action(const struct ofpact *a)
>      case OFPACT_NOTE:
>      case OFPACT_OUTPUT:
>      case OFPACT_OUTPUT_REG:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_POP_MPLS:
>      case OFPACT_POP_QUEUE:
>      case OFPACT_PUSH_MPLS:
> @@ -6025,6 +6124,7 @@ ofpact_is_allowed_in_actions_set(const struct ofpact *a)
>      case OFPACT_DEC_TTL:
>      case OFPACT_GROUP:
>      case OFPACT_OUTPUT:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_POP_MPLS:
>      case OFPACT_PUSH_MPLS:
>      case OFPACT_PUSH_VLAN:
> @@ -6249,6 +6349,7 @@ ovs_instruction_type_from_ofpact_type(enum ofpact_type type)
>      case OFPACT_CONTROLLER:
>      case OFPACT_ENQUEUE:
>      case OFPACT_OUTPUT_REG:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_BUNDLE:
>      case OFPACT_SET_VLAN_VID:
>      case OFPACT_SET_VLAN_PCP:
> @@ -6677,6 +6778,10 @@ ofpact_check__(enum ofputil_protocol *usable_protocols, struct ofpact *a,
>      case OFPACT_OUTPUT_REG:
>          return mf_check_src(&ofpact_get_OUTPUT_REG(a)->src, flow);
>
> +    case OFPACT_OUTPUT_TRUNC:
> +        return ofpact_check_output_port(ofpact_get_OUTPUT_TRUNC(a)->port,
> +                                        max_ports);
> +
>      case OFPACT_BUNDLE:
>          return bundle_check(ofpact_get_BUNDLE(a), max_ports, flow);
>
> @@ -7354,6 +7459,7 @@ ofpact_outputs_to_port(const struct ofpact *ofpact, ofp_port_t port)
>          return port == OFPP_CONTROLLER;
>
>      case OFPACT_OUTPUT_REG:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_BUNDLE:
>      case OFPACT_SET_VLAN_VID:
>      case OFPACT_SET_VLAN_PCP:
> diff --git a/ofproto/ofproto-dpif-sflow.c b/ofproto/ofproto-dpif-sflow.c
> index fbc82b7..5d26b7c 100644
> --- a/ofproto/ofproto-dpif-sflow.c
> +++ b/ofproto/ofproto-dpif-sflow.c
> @@ -1140,6 +1140,7 @@ dpif_sflow_read_actions(const struct flow *flow,
>             }
>             break;
>
> +       case OVS_ACTION_ATTR_TRUNC:
>         case OVS_ACTION_ATTR_USERSPACE:
>         case OVS_ACTION_ATTR_RECIRC:
>         case OVS_ACTION_ATTR_HASH:
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index f8c4a93..d46a52c 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -3995,6 +3995,56 @@ xlate_output_reg_action(struct xlate_ctx *ctx,
>  }
>
>  static void
> +xlate_output_trunc_action(struct xlate_ctx *ctx,
> +                    ofp_port_t port, uint32_t max_len)
> +{
> +    bool support_trunc = ctx->xbridge->support.trunc;
> +    struct ovs_action_trunc *trunc;
> +    char name[OFP_MAX_PORT_NAME_LEN];
> +
> +    switch (port) {
> +    case OFPP_TABLE:
> +    case OFPP_NORMAL:
> +    case OFPP_FLOOD:
> +    case OFPP_ALL:
> +    case OFPP_CONTROLLER:
> +    case OFPP_NONE:
> +        ofputil_port_to_string(port, name, sizeof name);
> +        xlate_report(ctx, "output_trunc does not support port: %s", name);
> +        break;
> +    case OFPP_LOCAL:
> +    case OFPP_IN_PORT:
> +    default:
> +        if (port != ctx->xin->flow.in_port.ofp_port) {
> +            const struct xport *xport = get_ofp_port(ctx->xbridge, port);
> +
> +            if (xport == NULL || xport->odp_port == ODPP_NONE) {
> +                /* Since truncate happens at its following output action, if
> +                 * the output port is a patch port, the behavior is somehow
> +                 * unpredicable. For simpilicity, disallow this case. */
> +                ofputil_port_to_string(port, name, sizeof name);
> +                XLATE_REPORT_ERROR(ctx, "bridge %s: "
> +                         "output_trunc does not support port: %s",
> +                         ctx->xbridge->name, name);
> +                break;
> +            }
> +
> +            trunc = nl_msg_put_unspec_uninit(ctx->odp_actions,
> +                                OVS_ACTION_ATTR_TRUNC,
> +                                sizeof *trunc);
> +            trunc->max_len = max_len;
> +            xlate_output_action(ctx, port, max_len, false);
> +            if (!support_trunc) {
> +                ctx->xout->slow |= SLOW_ACTION;
> +            }
> +        } else {
> +            xlate_report(ctx, "skipping output to input port");
> +        }
> +        break;
> +    }
> +}
> +
> +static void
>  xlate_enqueue_action(struct xlate_ctx *ctx,
>                       const struct ofpact_enqueue *enqueue)
>  {
> @@ -4333,6 +4383,7 @@ freeze_unroll_actions(const struct ofpact *a, const struct ofpact *end,
>      for (; a < end; a = ofpact_next(a)) {
>          switch (a->type) {
>          case OFPACT_OUTPUT_REG:
> +        case OFPACT_OUTPUT_TRUNC:
>          case OFPACT_GROUP:
>          case OFPACT_OUTPUT:
>          case OFPACT_CONTROLLER:
> @@ -4584,6 +4635,7 @@ recirc_for_mpls(const struct ofpact *a, struct xlate_ctx *ctx)
>
>      /* Output actions  do not require recirculation. */
>      case OFPACT_OUTPUT:
> +    case OFPACT_OUTPUT_TRUNC:
>      case OFPACT_ENQUEUE:
>      case OFPACT_OUTPUT_REG:
>      /* Set actions that don't touch L3+ fields do not require recirculation. */
> @@ -4933,6 +4985,11 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
>              xlate_output_reg_action(ctx, ofpact_get_OUTPUT_REG(a));
>              break;
>
> +        case OFPACT_OUTPUT_TRUNC:
> +            xlate_output_trunc_action(ctx, ofpact_get_OUTPUT_TRUNC(a)->port,
> +                                ofpact_get_OUTPUT_TRUNC(a)->max_len);
> +            break;
> +
>          case OFPACT_LEARN:
>              xlate_learn_action(ctx, ofpact_get_LEARN(a));
>              break;
> diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
> index 100e8d5..0cd1c25 100644
> --- a/ofproto/ofproto-dpif.c
> +++ b/ofproto/ofproto-dpif.c
> @@ -1212,6 +1212,63 @@ check_masked_set_action(struct dpif_backer *backer)
>      return !error;
>  }
>
> +/* Tests whether 'backer''s datapath supports truncation of a packet in
> + * OVS_ACTION_ATTR_TRUNC.  We need to disable some features on older
> + * datapaths that don't support this feature. */
> +static bool
> +check_trunc_action(struct dpif_backer *backer)
> +{
> +    struct eth_header *eth;
> +    struct ofpbuf actions;
> +    struct dpif_execute execute;
> +    struct dp_packet packet;
> +    struct ovs_action_trunc *trunc;
> +    struct flow flow;
> +    int error;
> +
> +    /* Compose an action with output(port:1,
> +     *              max_len:OVS_ACTION_OUTPUT_MIN + 1).
> +     * This translates to one truncate action and one output action. */
> +    ofpbuf_init(&actions, 64);
> +    trunc = nl_msg_put_unspec_uninit(&actions,
> +                            OVS_ACTION_ATTR_TRUNC, sizeof *trunc);
> +
> +    trunc->max_len = ETH_HEADER_LEN + 1;
> +    nl_msg_put_odp_port(&actions, OVS_ACTION_ATTR_OUTPUT, u32_to_odp(1));
> +
> +    /* Compose a dummy Ethernet packet. */
> +    dp_packet_init(&packet, ETH_HEADER_LEN);
> +    eth = dp_packet_put_zeros(&packet, ETH_HEADER_LEN);
> +    eth->eth_type = htons(0x1234);
> +
> +    flow_extract(&packet, &flow);
> +
> +    /* Execute the actions.  On older datapaths this fails with EINVAL, on
> +     * newer datapaths it succeeds. */
> +    execute.actions = actions.data;
> +    execute.actions_len = actions.size;
> +    execute.packet = &packet;
> +    execute.flow = &flow;
> +    execute.needs_help = false;
> +    execute.probe = true;
> +    execute.mtu = 0;
> +
> +    error = dpif_execute(backer->dpif, &execute);
> +
> +    dp_packet_uninit(&packet);
> +    ofpbuf_uninit(&actions);
> +
> +    if (error) {
> +        VLOG_INFO("%s: Datapath does not support truncate action",
> +                  dpif_name(backer->dpif));
> +    } else {
> +        VLOG_INFO("%s: Datapath supports truncate action",
> +                  dpif_name(backer->dpif));
> +    }
> +
> +    return !error;
> +}
> +
>  #define CHECK_FEATURE__(NAME, SUPPORT, FIELD, VALUE)                        \
>  static bool                                                                 \
>  check_##NAME(struct dpif_backer *backer)                                    \
> @@ -1263,6 +1320,7 @@ check_support(struct dpif_backer *backer)
>      backer->support.odp.recirc = check_recirc(backer);
>      backer->support.odp.max_mpls_depth = check_max_mpls_depth(backer);
>      backer->support.masked_set_action = check_masked_set_action(backer);
> +    backer->support.trunc = check_trunc_action(backer);
>      backer->support.ufid = check_ufid(backer);
>      backer->support.tnl_push_pop = dpif_supports_tnl_push_pop(backer->dpif);
>
> @@ -5343,6 +5401,24 @@ disable_tnl_push_pop(struct unixctl_conn *conn OVS_UNUSED, int argc OVS_UNUSED,
>  }
>
>  static void
> +disable_datapath_truncate(struct unixctl_conn *conn OVS_UNUSED,
> +                          int argc OVS_UNUSED,
> +                          const char *argv[] OVS_UNUSED,
> +                          void *aux OVS_UNUSED)
> +{
> +    const struct shash_node **backers;
> +    int i;
> +
> +    backers = shash_sort(&all_dpif_backers);
> +    for (i = 0; i < shash_count(&all_dpif_backers); i++) {
> +        struct dpif_backer *backer = backers[i]->data;
> +        backer->support.trunc = false;
> +    }
> +    free(backers);
> +    unixctl_command_reply(conn, "Datapath truncate action diabled");
> +}
> +
> +static void
>  ofproto_unixctl_init(void)
>  {
>      static bool registered;
> @@ -5376,6 +5452,9 @@ ofproto_unixctl_init(void)
>
>      unixctl_command_register("ofproto/tnl-push-pop", "[on]|[off]", 1, 1,
>                               disable_tnl_push_pop, NULL);
> +
> +    unixctl_command_register("dpif/disable-truncate", "", 0, 0,
> +                             disable_datapath_truncate, NULL);
>  }
>
>  /* Returns true if 'table' is the table used for internal rules,
> diff --git a/ofproto/ofproto-dpif.h b/ofproto/ofproto-dpif.h
> index 9e03b01..4034475 100644
> --- a/ofproto/ofproto-dpif.h
> +++ b/ofproto/ofproto-dpif.h
> @@ -90,6 +90,9 @@ struct dpif_backer_support {
>      /* True if the datapath supports OVS_FLOW_ATTR_UFID. */
>      bool ufid;
>
> +    /* True if the datapath supports OVS_ACTION_ATTR_TRUNC action. */
> +    bool trunc;
> +
>      /* Each member represents support for related OVS_KEY_ATTR_* fields. */
>      struct odp_support odp;
>  };
> diff --git a/tests/odp.at b/tests/odp.at
> index 7b94c92..e630855 100644
> --- a/tests/odp.at
> +++ b/tests/odp.at
> @@ -329,6 +329,7 @@ ct(commit,nat(src=fe80::20c:29ff:fe88:a18b,random))
>  ct(commit,nat(src=fe80::20c:29ff:fe88:1-fe80::20c:29ff:fe88:a18b,random))
>  ct(commit,nat(src=[[fe80::20c:29ff:fe88:1]]-[[fe80::20c:29ff:fe88:a18b]]:255-4096,random))
>  ct(commit,helper=ftp,nat(src=10.1.1.240-10.1.1.255))
> +trunc(100)
>  ])
>  AT_CHECK_UNQUOTED([ovstest test-odp parse-actions < actions.txt], [0],
>    [`cat actions.txt`
> diff --git a/tests/ofp-actions.at b/tests/ofp-actions.at
> index 50f74e9..ca4d1ba 100644
> --- a/tests/ofp-actions.at
> +++ b/tests/ofp-actions.at
> @@ -241,6 +241,9 @@ fe800000 00000000 020c 29ff fe88 0001 dnl
>  fe800000 00000000 020c 29ff fe88 a18b dnl
>  00ff1000 00000000
>
> +# actions=output(port=1,max_len=100)
> +ffff 0010 00002320 0027 0001 00000064
> +
>  # bad OpenFlow10 actions: NXBRC_MUST_BE_ZERO
>  ffff 0018 00002320 0025 0000 0005 0000 1122334455 000005
>
> diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
> index 9b94f3d..b0c6e0a 100644
> --- a/tests/ofproto-dpif.at
> +++ b/tests/ofproto-dpif.at
> @@ -5322,6 +5322,130 @@ PORTNAME
>         portName=p2
>  ])])
>
> +AT_SETUP([ofproto-dpif - basic truncate action])
> +OVS_VSWITCHD_START
> +add_of_ports br0 1 2 3 4 5
> +
> +AT_CHECK([ovs-vsctl -- set Interface p1 type=dummy options:pcap=p1.pcap])
> +AT_CHECK([ovs-vsctl -- set Interface p2 type=dummy options:pstream=punix:p2.sock])
> +AT_CHECK([ovs-vsctl -- set Interface p3 type=dummy   options:stream=unix:p2.sock])
> +AT_CHECK([ovs-vsctl -- set Interface p4 type=dummy options:pstream=punix:p4.sock])
> +AT_CHECK([ovs-vsctl -- set Interface p5 type=dummy   options:stream=unix:p4.sock])
> +
> +AT_DATA([flows.txt], [dnl
> +in_port=3,actions=drop
> +in_port=5,actions=drop
> +in_port=1,actions=output(port=2,max_len=64),output:4
> +])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +dnl Datapath actions
> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
> +AT_CHECK([tail -1 stdout], [0],
> +[Datapath actions: trunc(64),2,4
> +])
> +
> +dnl An 170 byte packet
> +AT_CHECK([ovs-appctl netdev-dummy/receive p1 '000c29c8a0a4005056c0000808004500009cb4a6000040019003c0a8da01c0a8da640800cb5fa762000556f431ad0009388e08090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f'])
> +
> +AT_CHECK([ovs-ofctl parse-pcap p1.pcap], [0], [dnl
> +icmp,in_port=ANY,vlan_tci=0x0000,dl_src=00:50:56:c0:00:08,dl_dst=00:0c:29:c8:a0:a4,nw_src=192.168.218.1,nw_dst=192.168.218.100,nw_tos=0,nw_ecn=0,nw_ttl=64,icmp_type=8,icmp_code=0
> +])
> +
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +dnl packet with truncated size
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=64
> +])
> +dnl packet with original size
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=170
> +])
> +
> +dnl More complicated case
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_DATA([flows.txt], [dnl
> +in_port=3,actions=drop
> +in_port=5,actions=drop
> +in_port=1,actions=output(port=2,max_len=64),output(port=2,max_len=128),output(port=4,max_len=60),output:2,output:4
> +])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +dnl Datapath actions
> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
> +AT_CHECK([tail -1 stdout], [0],
> +[Datapath actions: trunc(64),2,trunc(128),2,trunc(60),4,2,4
> +])
> +
> +dnl An 170 byte packet
> +AT_CHECK([ovs-appctl netdev-dummy/receive p1 '000c29c8a0a4005056c0000808004500009cb4a6000040019003c0a8da01c0a8da640800cb5fa762000556f431ad0009388e08090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f'])
> +
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +dnl packet size: 64 + 128 + 170 = 362
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=362
> +])
> +dnl packet size: 60 + 170 = 230
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=230
> +])
> +
> +dnl syntax checking
> +AT_CHECK([ovs-ofctl add-flow br0 'actions=output(port=ALL,max_len=100)'], [1], [], [dnl
> +ovs-ofctl: output to unsupported truncate port: ALL
> +])
> +
> +OVS_VSWITCHD_STOP
> +AT_CLEANUP
> +
> +AT_SETUP([ofproto-dpif - truncate and output to patch port])
> +OVS_VSWITCHD_START([add-br br1 \
> +-- set bridge br1 datapath-type=dummy fail-mode=secure \
> +-- add-port br1 pbr1 -- set int pbr1 type=patch options:peer=pbr0 ofport_request=1 \
> +-- add-port br0 pbr0 -- set int pbr0 type=patch options:peer=pbr1])
> +
> +add_of_ports br0 2
> +
> +AT_CHECK([ovs-ofctl add-flow br0 actions='output(port=1,max_len=100),output:2'])
> +AT_CHECK([ovs-ofctl add-flow br1 actions=NORMAL])
> +
> +AT_CHECK([ovs-appctl ofproto/trace br0 in_port=LOCAL,dl_src=10:20:30:40:50:60],
> +[0], [stdout])
> +AT_CHECK([tail -1 stdout], [0], [Datapath actions: 2
> +])
> +dnl the output(port=1,max_len=100) fails the translation, only output:2 in datapath
> +AT_CHECK([grep "output_trunc does not support port: [[0-9]]*" stdout], [0], [stdout])
> +
> +OVS_VSWITCHD_STOP
> +AT_CLEANUP
> +
> +AT_SETUP([ofproto-dpif - truncate and output to gre tunnel])
> +OVS_VSWITCHD_START([add-port br0 p1 -- set Interface p1 type=gre \
> +                    options:remote_ip=1.1.1.1 options:local_ip=2.2.2.2 \
> +                    options:key=5 ofport_request=1\
> +                    -- add-port br0 p2 -- set Interface p2 type=dummy \
> +                    ofport_request=2])
> +AT_DATA([flows.txt], [dnl
> +actions=output(max_len=100, port=1)
> +])
> +OVS_VSWITCHD_DISABLE_TUNNEL_PUSH_POP
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +AT_CHECK([ovs-appctl dpif/show | tail -n +3], [0], [dnl
> +               br0 65534/100: (dummy)
> +               p1 1/1: (gre: key=5, local_ip=2.2.2.2, remote_ip=1.1.1.1)
> +               p2 2/2: (dummy)
> +])
> +
> +dnl Basic
> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(2),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
> +AT_CHECK([tail -1 stdout], [0],
> +  [Datapath actions: trunc(100),set(tunnel(tun_id=0x5,src=2.2.2.2,dst=1.1.1.1,ttl=64,flags(df|key))),1
> +])
> +
> +OVS_VSWITCHD_STOP
> +AT_CLEANUP
> +
>  AT_SETUP([ofproto-dpif - sFlow packet sampling - IPv4 collector])
>  CHECK_SFLOW_SAMPLING_PACKET([127.0.0.1])
>  AT_CLEANUP
> diff --git a/tests/ovs-ofctl.at b/tests/ovs-ofctl.at
> index 613d9ce..71c4aab 100644
> --- a/tests/ovs-ofctl.at
> +++ b/tests/ovs-ofctl.at
> @@ -388,6 +388,10 @@ ip,actions=ct(commit,exec(load(0x1->NXM_NX_CT_LABEL[])))
>  ip,actions=ct(commit,exec(load(0x1234567890ABCDEF->NXM_NX_CT_LABEL[32..95])))
>  ip,actions=ct(commit,exec(set_field(0x1->ct_label)))
>  ip,ct_state=+trk,ct_label=0x1234567890abcdef12345678,actions=ct(commit)
> +actions=output(max_len=100,port=123)
> +actions=output(port=100,max_len=123)
> +actions=output(port=LOCAL,max_len=123)
> +actions=output(port=IN_PORT,max_len=123)
>  ]])
>
>  AT_CHECK([ovs-ofctl parse-flows flows.txt
> @@ -431,6 +435,10 @@ NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1->NXM_NX_CT_LABEL[
>  NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1234567890abcdef->NXM_NX_CT_LABEL[32..95]))
>  NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1->NXM_NX_CT_LABEL[0..63],load:0->NXM_NX_CT_LABEL[64..127]))
>  NXT_FLOW_MOD: ADD table:255 ct_state=+trk,ct_label=0x1234567890abcdef12345678,ip actions=ct(commit)
> +NXT_FLOW_MOD: ADD table:255 actions=output(port=123,max_len=100)
> +NXT_FLOW_MOD: ADD table:255 actions=output(port=100,max_len=123)
> +NXT_FLOW_MOD: ADD table:255 actions=output(port=65534,max_len=123)
> +NXT_FLOW_MOD: ADD table:255 actions=output(port=65528,max_len=123)
>  ]])
>  AT_CLEANUP
>
> diff --git a/tests/system-kmod-macros.at b/tests/system-kmod-macros.at
> index cee0510..a3e4dd7 100644
> --- a/tests/system-kmod-macros.at
> +++ b/tests/system-kmod-macros.at
> @@ -66,3 +66,10 @@ m4_define([CHECK_CONNTRACK],
>       on_exit 'ovstest test-netlink-conntrack flush'
>      ]
>  )
> +
> +# CHECK_KERNEL_DP, CHECK_USER_DP
> +#
> +# Ignore the CHECK_USER_DP and execute the CHECK_KERNEL_DP
> +#
> +m4_define([CHECK_KERNEL_DP], [$1])
> +m4_define([CHECK_USER_DP], [])
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index 5ce3955..606bc9b 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -250,6 +250,253 @@ NS_CHECK_EXEC([at_ns0], [ping -s 3200 -q -c 3 -i 0.3 -w 2 10.1.1.100 | FORMAT_PI
>  OVS_TRAFFIC_VSWITCHD_STOP
>  AT_CLEANUP
>
> +AT_SETUP([datapath - basic truncate action])
> +OVS_TRAFFIC_VSWITCHD_START()
> +AT_CHECK([ovs-ofctl del-flows br0])
> +
> +dnl Create p0 and ovs-p0(1)
> +ADD_NAMESPACES(at_ns0)
> +ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24")
> +NS_CHECK_EXEC([at_ns0], [ip link set dev p0 address e6:66:c1:11:11:11])
> +NS_CHECK_EXEC([at_ns0], [arp -s 10.1.1.2 e6:66:c1:22:22:22])
> +
> +dnl Create p1(3) and ovs-p1(2), packets received from ovs-p1 will appear in p1
> +AT_CHECK([ip link add p1 type veth peer name ovs-p1])
> +on_exit 'ip link del ovs-p1'
> +AT_CHECK([ip link set dev ovs-p1 up])
> +AT_CHECK([ip link set dev p1 up])
> +AT_CHECK([ovs-vsctl add-port br0 ovs-p1 -- set interface ovs-p1 ofport_request=2])
> +dnl Use p1 to check the truncated packet
> +AT_CHECK([ovs-vsctl add-port br0 p1 -- set interface p1 ofport_request=3])
> +
> +dnl Create p2(5) and ovs-p2(4)
> +AT_CHECK([ip link add p2 type veth peer name ovs-p2])
> +on_exit 'ip link del ovs-p2'
> +AT_CHECK([ip link set dev ovs-p2 up])
> +AT_CHECK([ip link set dev p2 up])
> +AT_CHECK([ovs-vsctl add-port br0 ovs-p2 -- set interface ovs-p2 ofport_request=4])
> +dnl Use p2 to check the truncated packet
> +AT_CHECK([ovs-vsctl add-port br0 p2 -- set interface p2 ofport_request=5])
> +
> +dnl basic test
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_DATA([flows.txt], [dnl
> +in_port=3 dl_dst=e6:66:c1:22:22:22 actions=drop
> +in_port=5 dl_dst=e6:66:c1:22:22:22 actions=drop
> +in_port=1 dl_dst=e6:66:c1:22:22:22 actions=output(port=2,max_len=100),output:4
> +])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +dnl use this file as payload file for ncat
> +AT_CHECK([dd if=/dev/urandom of=payload200.bin bs=200 count=1 2> /dev/null])
> +on_exit 'rm -f payload200.bin'
> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
> +
> +dnl packet with truncated size
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" |  sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=100
> +])
> +dnl packet with original size
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=242
> +])
> +
> +dnl more complicated output actions
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_DATA([flows.txt], [dnl
> +in_port=3 dl_dst=e6:66:c1:22:22:22 actions=drop
> +in_port=5 dl_dst=e6:66:c1:22:22:22 actions=drop
> +in_port=1 dl_dst=e6:66:c1:22:22:22 actions=output(port=2,max_len=100),output:4,output(port=2,max_len=100),output(port=4,max_len=100),output:2,output(port=4,max_len=200),output(port=2,max_len=65535)
> +])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
> +
> +dnl 100 + 100 + 242 + min(65535,242) = 684
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=684
> +])
> +dnl 242 + 100 + min(242,200) = 542
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=542
> +])
> +
> +dnl SLOW_ACTION: disable kernel datapath truncate support
> +dnl Repeat the test above, but exercise the SLOW_ACTION code path
> +AT_CHECK([ovs-appctl dpif/disable-truncate], [0],
> +[Datapath truncate action diabled
> +])
> +
> +dnl SLOW_ACTION test1: check datapatch actions
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +CHECK_KERNEL_DP(
> +AT_CHECK([ovs-appctl ofproto/trace system 'in_port(2),eth(src=e6:66:c1:11:11:11,dst=e6:66:c1:22:22:22),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
> +AT_CHECK([tail -3 stdout], [0],
> +[Datapath actions: trunc(100),3,5,trunc(100),3,trunc(100),5,3,trunc(200),5,trunc(65535),3
> +This flow is handled by the userspace slow path because it:
> +       - Uses action(s) not supported by datapath.
> +])
> +)
> +
> +dnl SLOW_ACTION test2: check actual packet truncate
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
> +
> +dnl 100 + 100 + 242 + min(65535,242) = 684
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=684
> +])
> +
> +dnl 242 + 100 + min(242,200) = 542
> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=542
> +])
> +
> +OVS_TRAFFIC_VSWITCHD_STOP
> +AT_CLEANUP
> +
> +dnl Create 2 bridges and 2 namespaces to test truncate over
> +dnl GRE tunnel:
> +dnl   br0: overlay bridge
> +dnl   ns1: connect to br0, with IP:10.1.1.2
> +dnl   br-underlay: with IP: 172.31.1.100
> +dnl   ns0: connect to br-underlay, with IP: 10.1.1.1
> +AT_SETUP([datapath - truncate and output to gre tunnel])
> +OVS_CHECK_GRE()
> +OVS_TRAFFIC_VSWITCHD_START()
> +
> +ADD_BR([br-underlay])
> +ADD_NAMESPACES(at_ns0)
> +ADD_NAMESPACES(at_ns1)
> +AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
> +AT_CHECK([ovs-ofctl add-flow br-underlay "actions=normal"])
> +
> +dnl Set up underlay link from host into the namespace using veth pair.
> +ADD_VETH(p0, at_ns0, br-underlay, "172.31.1.1/24")
> +AT_CHECK([ip addr add dev br-underlay "172.31.1.100/24"])
> +AT_CHECK([ip link set dev br-underlay up])
> +
> +dnl Set up tunnel endpoints on OVS outside the namespace and with a native
> +dnl linux device inside the namespace.
> +ADD_OVS_TUNNEL([gre], [br0], [at_gre0], [172.31.1.1], [10.1.1.100/24])
> +ADD_NATIVE_TUNNEL([gretap], [ns_gre0], [at_ns0], [172.31.1.100], [10.1.1.1/24])
> +AT_CHECK([ovs-vsctl -- set interface at_gre0 ofport_request=1])
> +NS_CHECK_EXEC([at_ns0], [ip link set dev ns_gre0 address e6:66:c1:11:11:11])
> +NS_CHECK_EXEC([at_ns0], [arp -s 10.1.1.2 e6:66:c1:22:22:22])
> +
> +dnl Set up (p1 and ovs-p1) at br0
> +ADD_VETH(p1, at_ns1, br0, '10.1.1.2/24')
> +AT_CHECK([ovs-vsctl -- set interface ovs-p1 ofport_request=2])
> +NS_CHECK_EXEC([at_ns1], [ip link set dev p1 address e6:66:c1:22:22:22])
> +NS_CHECK_EXEC([at_ns1], [arp -s 10.1.1.1 e6:66:c1:11:11:11])
> +
> +dnl Set up (p2 and ovs-p2) as loopback for verifying packet size
> +AT_CHECK([ip link add p2 type veth peer name ovs-p2])
> +on_exit 'ip link del ovs-p2'
> +AT_CHECK([ip link set dev ovs-p2 up])
> +AT_CHECK([ip link set dev p2 up])
> +AT_CHECK([ovs-vsctl add-port br0 ovs-p2 -- set interface ovs-p2 ofport_request=3])
> +AT_CHECK([ovs-vsctl add-port br0 p2 -- set interface p2 ofport_request=4])
> +
> +dnl use this file as payload file for ncat
> +AT_CHECK([dd if=/dev/urandom of=payload200.bin bs=200 count=1 2> /dev/null])
> +on_exit 'rm -f payload200.bin'
> +
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_DATA([flows.txt], [dnl
> +priority=99,in_port=1,actions=output(port=2,max_len=100),output(port=3,max_len=100)
> +priority=99,in_port=2,udp,actions=output(port=1,max_len=100)
> +priority=1,in_port=4,ip,actions=drop
> +priority=1,actions=drop
> +])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +AT_CHECK([ovs-ofctl del-flows br-underlay])
> +AT_DATA([flows-underlay.txt], [dnl
> +priority=99,dl_type=0x0800,nw_proto=47,in_port=1,actions=LOCAL
> +priority=99,dl_type=0x0800,nw_proto=47,in_port=LOCAL,ip_dst=172.31.1.1/24,actions=1
> +priority=1,actions=drop
> +])
> +
> +AT_CHECK([ovs-ofctl add-flows br-underlay flows-underlay.txt])
> +
> +dnl check tunnel push path, from at_ns1 to at_ns0
> +NS_CHECK_EXEC([at_ns1], [nc -u 10.1.1.1 1234 < payload200.bin])
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +
> +dnl Before truncation = ETH(14) + IP(20) + UDP(8) + 200 = 242B
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=2" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=242
> +])
> +dnl After truncation = outer ETH(14) + outer IP(20) + GRE(4) + 100 = 138B
> +AT_CHECK([ovs-ofctl dump-flows br-underlay | grep "in_port=LOCAL" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=138
> +])
> +
> +dnl check tunnel pop path, from at_ns0 to at_ns1
> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 5678 < payload200.bin])
> +dnl After truncation = 100 byte at loopback device p2(4)
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=4" | awk --field-separator=', '  '{print $5}'], [0], [dnl
> +n_bytes=100
> +])
> +
> +dnl SLOW_ACTION: disable datapath truncate support
> +dnl Repeat the test above, but exercise the SLOW_ACTION code path
> +AT_CHECK([ovs-appctl dpif/disable-truncate], [0],
> +[Datapath truncate action diabled
> +])
> +
> +dnl SLOW_ACTION test1: check datapatch actions
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +
> +CHECK_KERNEL_DP(
> +AT_CHECK([ovs-appctl ofproto/trace system 'in_port(5),eth(src=e6:66:c1:11:11:11,dst=e6:66:c1:22:22:22),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=17,tos=4,ttl=128,frag=no),udp(src=8,dst=9)'], [0], [stdout])
> +AT_CHECK([tail -3 stdout], [0],
> +[Datapath actions: trunc(100),set(tunnel(dst=172.31.1.1,ttl=64,flags(df))),4
> +This flow is handled by the userspace slow path because it:
> +       - Uses action(s) not supported by datapath.
> +])
> +)
> +
> +dnl SLOW_ACTION test2: check actual packet truncate
> +AT_CHECK([ovs-ofctl del-flows br0])
> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
> +AT_CHECK([ovs-ofctl del-flows br-underlay])
> +AT_CHECK([ovs-ofctl add-flows br-underlay flows-underlay.txt])
> +
> +dnl check tunnel push path, from at_ns1 to at_ns0
> +NS_CHECK_EXEC([at_ns1], [nc -u 10.1.1.1 1234 < payload200.bin])
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +
> +dnl Before truncation = ETH(14) + IP(20) + UDP(8) + 200 = 242B
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=2" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=242
> +])
> +dnl After truncation = outer ETH(14) + outer IP(20) + GRE(4) + 100 = 138B
> +AT_CHECK([ovs-ofctl dump-flows br-underlay | grep "in_port=LOCAL" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
> +n_bytes=138
> +])
> +
> +dnl check tunnel pop path, from at_ns0 to at_ns1
> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 5678 < payload200.bin])
> +dnl After truncation = 100 byte at loopback device p2(4)
> +AT_CHECK([ovs-appctl revalidator/purge], [0])
> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=4" | awk --field-separator=', '  '{print $5}'], [0], [dnl
> +n_bytes=100
> +])
> +
> +OVS_TRAFFIC_VSWITCHD_STOP
> +AT_CLEANUP
> +
>  AT_SETUP([conntrack - controller])
>  CHECK_CONNTRACK()
>  OVS_TRAFFIC_VSWITCHD_START()
> diff --git a/tests/system-userspace-macros.at b/tests/system-userspace-macros.at
> index c09a4aa..dc4bd0e 100644
> --- a/tests/system-userspace-macros.at
> +++ b/tests/system-userspace-macros.at
> @@ -66,3 +66,10 @@ m4_define([CONFIGURE_VETH_OFFLOADS],
>  m4_define([CHECK_CONNTRACK],
>      [AT_SKIP_IF(true)]
>  )
> +
> +# CHECK_KERNEL_DP, CHECK_USER_DP
> +#
> +# Ignore the CHECK_KERNEL_DP and execute the CHECK_USER_DP
> +#
> +m4_define([CHECK_KERNEL_DP], [])
> +m4_define([CHECK_USER_DP], [$1])
> --
Test looks good.

packet truncate support documentation is missing in man page. NEWS
also needs to be updated.

Thanks, I will update and resubmit.

On Thu, Jun 23, 2016 at 3:28 PM, pravin shelar <pshelar@ovn.org> wrote:
> On Wed, Jun 22, 2016 at 10:02 PM, William Tu <u9012063@gmail.com> wrote:
>> The patch adds a new action to support packet truncation.  The new action
>> is formatted as 'output(port=n,max_len=m)', as output to port n, with
>> packet size being MIN(original_size, m).
>>
>> One use case is to enable port mirroring to send smaller packets to the
>> destination port so that only useful packet information is mirrored/copied,
>> saving some performance overhead of copying entire packet payload.  Example
>> use case is below as well as shown in the testcases:
>>
>>     - Output to port 1 with max_len 100 bytes.
>>     - The output packet size on port 1 will be MIN(original_packet_size, 100).
>>     # ovs-ofctl add-flow br0 'actions=output(port=1,max_len=100)'
>>
>>     - The scope of max_len is limited to output action itself.  The following
>>       packet size of output:1 and output:2 will be intact.
>>     # ovs-ofctl add-flow br0 \
>>             'actions=output(port=1,max_len=100),output:1,output:2'
>>     - The Datapath actions shows:
>>     # Datapath actions: trunc(100),1,1,2
>>
>> Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/139668398
>> Signed-off-by: William Tu <u9012063@gmail.com>
>> ---
>>  include/openvswitch/ofp-actions.h |  10 ++
>>  lib/dp-packet.c                   |   2 +
>>  lib/dp-packet.h                   |  67 +++++++++++
>>  lib/dpif-netdev.c                 |  33 ++++-
>>  lib/dpif.c                        |  25 +++-
>>  lib/dpif.h                        |   1 +
>>  lib/netdev-bsd.c                  |   3 +
>>  lib/netdev-dpdk.c                 |  21 ++++
>>  lib/netdev-dummy.c                |   2 +
>>  lib/netdev-linux.c                |   3 +
>>  lib/netdev.c                      |   5 +-
>>  lib/odp-execute.c                 |  12 ++
>>  lib/odp-util.c                    |  23 ++++
>>  lib/ofp-actions.c                 | 106 ++++++++++++++++
>>  ofproto/ofproto-dpif-sflow.c      |   1 +
>>  ofproto/ofproto-dpif-xlate.c      |  57 +++++++++
>>  ofproto/ofproto-dpif.c            |  79 ++++++++++++
>>  ofproto/ofproto-dpif.h            |   3 +
>>  tests/odp.at                      |   1 +
>>  tests/ofp-actions.at              |   3 +
>>  tests/ofproto-dpif.at             | 124 +++++++++++++++++++
>>  tests/ovs-ofctl.at                |   8 ++
>>  tests/system-kmod-macros.at       |   7 ++
>>  tests/system-traffic.at           | 247 ++++++++++++++++++++++++++++++++++++++
>>  tests/system-userspace-macros.at  |   7 ++
>>  25 files changed, 846 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/openvswitch/ofp-actions.h b/include/openvswitch/ofp-actions.h
>> index 91c7ee5..0b8ccbb 100644
>> --- a/include/openvswitch/ofp-actions.h
>> +++ b/include/openvswitch/ofp-actions.h
>> @@ -108,6 +108,7 @@
>>      OFPACT(UNROLL_XLATE,    ofpact_unroll_xlate, ofpact, "unroll_xlate") \
>>      OFPACT(CT,              ofpact_conntrack,   ofpact, "ct")           \
>>      OFPACT(NAT,             ofpact_nat,         ofpact, "nat")          \
>> +    OFPACT(OUTPUT_TRUNC,    ofpact_output_trunc,ofpact, "output_trunc") \
>>                                                                          \
>>      /* Debugging actions.                                               \
>>       *                                                                  \
>> @@ -290,6 +291,15 @@ struct ofpact_output_reg {
>>      struct mf_subfield src;
>>  };
>>
>> +/* OFPACT_OUTPUT_TRUNC.
>> + *
>> + * Used for NXAST_OUTPUT_TRUNC. */
>> +struct ofpact_output_trunc {
>> +    struct ofpact ofpact;
>> +    ofp_port_t port;            /* Output port. */
>> +    uint32_t max_len;           /* Max send len. */
>> +};
>> +
>>  /* Bundle slave choice algorithm to apply.
>>   *
>>   * In the descriptions below, 'slaves' is the list of possible slaves in the
>> diff --git a/lib/dp-packet.c b/lib/dp-packet.c
>> index 0c85d50..8e7defc 100644
>> --- a/lib/dp-packet.c
>> +++ b/lib/dp-packet.c
>> @@ -30,6 +30,7 @@ dp_packet_init__(struct dp_packet *b, size_t allocated, enum dp_packet_source so
>>      dp_packet_reset_offsets(b);
>>      pkt_metadata_init(&b->md, 0);
>>      dp_packet_rss_invalidate(b);
>> +    dp_packet_reset_cutlen(b);
>>  }
>>
>>  static void
>> @@ -168,6 +169,7 @@ dp_packet_clone_with_headroom(const struct dp_packet *buffer, size_t headroom)
>>      new_buffer->l3_ofs = buffer->l3_ofs;
>>      new_buffer->l4_ofs = buffer->l4_ofs;
>>      new_buffer->md = buffer->md;
>> +    new_buffer->cutlen = buffer->cutlen;
>>  #ifdef DPDK_NETDEV
>>      new_buffer->mbuf.ol_flags = buffer->mbuf.ol_flags;
>>  #else
>> diff --git a/lib/dp-packet.h b/lib/dp-packet.h
>> index 118c84d..f505fa5 100644
>> --- a/lib/dp-packet.h
>> +++ b/lib/dp-packet.h
>> @@ -60,6 +60,7 @@ struct dp_packet {
>>                                      * or UINT16_MAX. */
>>      uint16_t l4_ofs;               /* Transport-level header offset,
>>                                        or UINT16_MAX. */
>> +    uint32_t cutlen;               /* length in bytes to cut from the end. */
>>      union {
>>          struct pkt_metadata md;
>>          uint64_t data[DP_PACKET_CONTEXT_SIZE / 8];
>> @@ -494,6 +495,34 @@ dp_packet_set_allocated(struct dp_packet *b, uint16_t s)
>>  }
>>  #endif
>>
>> +static inline void
>> +dp_packet_reset_cutlen(struct dp_packet *b)
>> +{
>> +    b->cutlen = 0;
>> +}
>> +
>> +static inline uint32_t
>> +dp_packet_set_cutlen(struct dp_packet *b, uint32_t max_len)
>> +{
>> +    if (max_len < ETH_HEADER_LEN) {
>> +        max_len = ETH_HEADER_LEN;
>> +    }
>> +
>> +    if (max_len >= dp_packet_size(b)) {
>> +        b->cutlen = 0;
>> +    } else {
>> +        b->cutlen = dp_packet_size(b) - max_len;
>> +    }
>> +    return b->cutlen;
>> +}
>> +
>> +static inline uint32_t
>> +dp_packet_get_cutlen(struct dp_packet *b)
>> +{
>> +    /* Always in valid range if user uses dp_packet_set_cutlen. */
>> +    return b->cutlen;
>> +}
>> +
>>  static inline void *
>>  dp_packet_data(const struct dp_packet *b)
>>  {
>> @@ -567,12 +596,14 @@ enum { NETDEV_MAX_BURST = 32 }; /* Maximum number packets in a batch. */
>>
>>  struct dp_packet_batch {
>>      int count;
>> +    bool trunc; /* true if the batch needs truncate. */
>>      struct dp_packet *packets[NETDEV_MAX_BURST];
>>  };
>>
>>  static inline void dp_packet_batch_init(struct dp_packet_batch *b)
>>  {
>>      b->count = 0;
>> +    b->trunc = false;
>>  }
>>
>>  static inline void
>> @@ -585,12 +616,14 @@ dp_packet_batch_clone(struct dp_packet_batch *dst,
>>          dst->packets[i] = dp_packet_clone(src->packets[i]);
>>      }
>>      dst->count = src->count;
>> +    dst->trunc = src->trunc;
>>  }
>>
>>  static inline void
>>  packet_batch_init_packet(struct dp_packet_batch *b, struct dp_packet *p)
>>  {
>>      b->count = 1;
>> +    b->trunc = false;
>>      b->packets[0] = p;
>>  }
>>
>> @@ -606,6 +639,40 @@ dp_packet_delete_batch(struct dp_packet_batch *batch, bool may_steal)
>>      }
>>  }
>>
>> +static inline void
>> +dp_packet_batch_apply_cutlen(struct dp_packet_batch *pktb)
>> +{
>> +    int i;
>> +
>> +    if (!pktb->trunc)
>> +        return;
>> +
>> +    for (i = 0; i < pktb->count; i++) {
>> +        uint32_t cutlen = dp_packet_get_cutlen(pktb->packets[i]);
>> +
>> +        if (cutlen > 0) {
>> +            dp_packet_set_size(pktb->packets[i],
>> +                dp_packet_size(pktb->packets[i]) - cutlen);
>> +            dp_packet_reset_cutlen(pktb->packets[i]);
>> +        }
>> +    }
>> +    pktb->trunc = false;
>> +}
>> +
>> +static inline void
>> +dp_packet_batch_reset_cutlen(struct dp_packet_batch *pktb)
>> +{
>> +    int i;
>> +
>> +    if (!pktb->trunc)
>> +        return;
>> +
>> +    pktb->trunc = false;
>> +    for (i = 0; i < pktb->count; i++) {
>> +        dp_packet_reset_cutlen(pktb->packets[i]);
>> +    }
>> +}
>> +
>>  #ifdef  __cplusplus
>>  }
>>  #endif
>> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
>> index 8d39d9e..70f320d 100644
>> --- a/lib/dpif-netdev.c
>> +++ b/lib/dpif-netdev.c
>> @@ -4057,13 +4057,17 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>>      case OVS_ACTION_ATTR_TUNNEL_PUSH:
>>          if (*depth < MAX_RECIRC_DEPTH) {
>>              struct dp_packet_batch tnl_pkt;
>> +            struct dp_packet_batch *orig_packets_ = packets_;
>>              int err;
>>
>>              if (!may_steal) {
>>                  dp_packet_batch_clone(&tnl_pkt, packets_);
>>                  packets_ = &tnl_pkt;
>> +                dp_packet_batch_reset_cutlen(orig_packets_);
>>              }
>>
>> +            dp_packet_batch_apply_cutlen(packets_);
>> +
>>              err = push_tnl_action(pmd, a, packets_);
>>              if (!err) {
>>                  (*depth)++;
>> @@ -4076,6 +4080,7 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>>
>>      case OVS_ACTION_ATTR_TUNNEL_POP:
>>          if (*depth < MAX_RECIRC_DEPTH) {
>> +            struct dp_packet_batch *orig_packets_ = packets_;
>>              odp_port_t portno = u32_to_odp(nl_attr_get_u32(a));
>>
>>              p = pmd_tx_port_cache_lookup(pmd, portno);
>> @@ -4084,10 +4089,13 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>>                  int i;
>>
>>                  if (!may_steal) {
>> -                   dp_packet_batch_clone(&tnl_pkt, packets_);
>> -                   packets_ = &tnl_pkt;
>> +                    dp_packet_batch_clone(&tnl_pkt, packets_);
>> +                    packets_ = &tnl_pkt;
>> +                    dp_packet_batch_reset_cutlen(orig_packets_);
>>                  }
>>
>> +                dp_packet_batch_apply_cutlen(packets_);
>> +
>>                  netdev_pop_header(p->netdev, packets_);
>>                  if (!packets_->count) {
>>                      return;
>> @@ -4107,22 +4115,42 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>>
>>      case OVS_ACTION_ATTR_USERSPACE:
>>          if (!fat_rwlock_tryrdlock(&dp->upcall_rwlock)) {
>> +            struct dp_packet_batch *orig_packets_ = packets_;
>>              struct dp_packet **packets = packets_->packets;
>>              const struct nlattr *userdata;
>> +            struct dp_packet_batch usr_pkt;
>>              struct ofpbuf actions;
>>              struct flow flow;
>>              ovs_u128 ufid;
>> +            bool clone = false;
>>              int i;
>>
>>              userdata = nl_attr_find_nested(a, OVS_USERSPACE_ATTR_USERDATA);
>>              ofpbuf_init(&actions, 0);
>>
>> +            if (packets_->trunc) {
>> +                if (!may_steal) {
>> +                    dp_packet_batch_clone(&usr_pkt, packets_);
>> +                    packets_ = &usr_pkt;
>> +                    packets = packets_->packets;
>> +                    clone = true;
>> +                    dp_packet_batch_reset_cutlen(orig_packets_);
>> +                }
>> +
>> +                dp_packet_batch_apply_cutlen(packets_);
>> +            }
>> +
>>              for (i = 0; i < packets_->count; i++) {
>>                  flow_extract(packets[i], &flow);
>>                  dpif_flow_hash(dp->dpif, &flow, sizeof flow, &ufid);
>>                  dp_execute_userspace_action(pmd, packets[i], may_steal, &flow,
>>                                              &ufid, &actions, userdata);
>>              }
>> +
>> +            if (clone) {
>> +                dp_packet_delete_batch(packets_, true);
>> +            }
>> +
>>              ofpbuf_uninit(&actions);
>>              fat_rwlock_unlock(&dp->upcall_rwlock);
>>
>> @@ -4170,6 +4198,7 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_,
>>      case OVS_ACTION_ATTR_SAMPLE:
>>      case OVS_ACTION_ATTR_HASH:
>>      case OVS_ACTION_ATTR_UNSPEC:
>> +    case OVS_ACTION_ATTR_TRUNC:
>>      case __OVS_ACTION_ATTR_MAX:
>>          OVS_NOT_REACHED();
>>      }
>> diff --git a/lib/dpif.c b/lib/dpif.c
>> index c4f24c7..5f1be41 100644
>> --- a/lib/dpif.c
>> +++ b/lib/dpif.c
>> @@ -1092,6 +1092,7 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>>      struct dpif_execute_helper_aux *aux = aux_;
>>      int type = nl_attr_type(action);
>>      struct dp_packet *packet = packets_->packets[0];
>> +    struct dp_packet *trunc_packet = NULL, *orig_packet;
>>
>>      ovs_assert(packets_->count == 1);
>>
>> @@ -1106,7 +1107,8 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>>          struct ofpbuf execute_actions;
>>          uint64_t stub[256 / 8];
>>          struct pkt_metadata *md = &packet->md;
>> -        bool dst_set;
>> +        bool dst_set, clone = false;
>> +        uint32_t cutlen = dp_packet_get_cutlen(packet);
>>
>>          dst_set = flow_tnl_dst_is_set(&md->tunnel);
>>          if (dst_set) {
>> @@ -1124,6 +1126,22 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>>              execute.actions_len = NLA_ALIGN(action->nla_len);
>>          }
>>
>> +        orig_packet = packet;
>> +
>> +        if (cutlen > 0 && (type == OVS_ACTION_ATTR_OUTPUT ||
>> +            type == OVS_ACTION_ATTR_TUNNEL_PUSH ||
>> +            type == OVS_ACTION_ATTR_TUNNEL_POP ||
>> +            type == OVS_ACTION_ATTR_USERSPACE)) {
>> +            if (!may_steal) {
>> +                trunc_packet = dp_packet_clone(packet);
>> +                packet = trunc_packet;
>> +                clone = true;
>> +            }
>> +
>> +            dp_packet_set_size(packet, dp_packet_size(packet) - cutlen);
>> +            dp_packet_reset_cutlen(orig_packet);
>> +        }
>> +
>>          execute.packet = packet;
>>          execute.flow = aux->flow;
>>          execute.needs_help = false;
>> @@ -1135,6 +1153,10 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>>          if (dst_set) {
>>              ofpbuf_uninit(&execute_actions);
>>          }
>> +
>> +        if (clone) {
>> +            dp_packet_delete(trunc_packet);
>> +        }
>>          break;
>>      }
>>
>> @@ -1146,6 +1168,7 @@ dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
>>      case OVS_ACTION_ATTR_SET:
>>      case OVS_ACTION_ATTR_SET_MASKED:
>>      case OVS_ACTION_ATTR_SAMPLE:
>> +    case OVS_ACTION_ATTR_TRUNC:
>>      case OVS_ACTION_ATTR_UNSPEC:
>>      case __OVS_ACTION_ATTR_MAX:
>>          OVS_NOT_REACHED();
>> diff --git a/lib/dpif.h b/lib/dpif.h
>> index 6788301..981868c 100644
>> --- a/lib/dpif.h
>> +++ b/lib/dpif.h
>> @@ -784,6 +784,7 @@ struct dpif_upcall {
>>      size_t key_len;             /* Length of 'key' in bytes. */
>>      ovs_u128 ufid;              /* Unique flow identifier for 'key'. */
>>      struct nlattr *mru;         /* Maximum receive unit. */
>> +    struct nlattr *cutlen;      /* Number of bytes shrink from the end. */
>>
>>      /* DPIF_UC_ACTION only. */
>>      struct nlattr *userdata;    /* Argument to OVS_ACTION_ATTR_USERSPACE. */
>> diff --git a/lib/netdev-bsd.c b/lib/netdev-bsd.c
>> index 43fa982..2e92d97 100644
>> --- a/lib/netdev-bsd.c
>> +++ b/lib/netdev-bsd.c
>> @@ -699,6 +699,9 @@ netdev_bsd_send(struct netdev *netdev_, int qid OVS_UNUSED,
>>          const void *data = dp_packet_data(pkts[i]);
>>          size_t size = dp_packet_size(pkts[i]);
>>
>> +        /* Truncate the packet if it is configured. */
>> +        size -= dp_packet_get_cutlen(pkts[i]);
>> +
>>          while (!error) {
>>              ssize_t retval;
>>              if (dev->tap_fd >= 0) {
>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
>> index fc0c8d3..8063add 100644
>> --- a/lib/netdev-dpdk.c
>> +++ b/lib/netdev-dpdk.c
>> @@ -1487,6 +1487,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts,
>>
>>      for (i = 0; i < cnt; i++) {
>>          int size = dp_packet_size(pkts[i]);
>> +        int cutlen = dp_packet_get_cutlen(pkts[i]);
>>
>>          if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>>              VLOG_WARN_RL(&rl, "Too big size %d max_packet_len %d",
>> @@ -1503,6 +1504,12 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet **pkts,
>>              break;
>>          }
>>
>> +        if (OVS_UNLIKELY(cutlen > 0)) {
>> +            /* Cut the size so only the truncated size is copied. */
>> +            size -= cutlen;
>> +            dp_packet_reset_cutlen(pkts[i]);
>> +        }
>> +
> As commented in last review, there is no need to check for cut length
> anywhere while setting the size.
>
>>          /* We have to do a copy for now */
>>          memcpy(rte_pktmbuf_mtod(mbufs[newcnt], void *), dp_packet_data(pkts[i]), size);
>>
>> @@ -1550,6 +1557,14 @@ netdev_dpdk_vhost_send(struct netdev *netdev, int qid, struct dp_packet **pkts,
>>              }
>>          }
>>      } else {
>> +        int i;
>> +
>> +        for (i = 0; i < cnt; i++) {
>> +            int cutlen = dp_packet_get_cutlen(pkts[i]);
>> +
>> +            dp_packet_set_size(pkts[i], dp_packet_size(pkts[i]) - cutlen);
>> +            dp_packet_reset_cutlen(pkts[i]);
>> +        }
>>          __netdev_dpdk_vhost_send(netdev, qid, pkts, cnt, may_steal);
>>      }
>>      return 0;
>> @@ -1585,6 +1600,12 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid,
>>
>>          for (i = 0; i < cnt; i++) {
>>              int size = dp_packet_size(pkts[i]);
>> +            uint32_t cutlen = dp_packet_get_cutlen(pkts[i]);
>> +
>> +            if (OVS_UNLIKELY(cutlen > 0)) {
>> +                size -= cutlen;
>> +                dp_packet_set_size(pkts[i], size);
>> +            }
>>
>>              if (OVS_UNLIKELY(size > dev->max_packet_len)) {
>>                  if (next_tx_idx != i) {
>> diff --git a/lib/netdev-dummy.c b/lib/netdev-dummy.c
>> index aa244b6..127b6ae 100644
>> --- a/lib/netdev-dummy.c
>> +++ b/lib/netdev-dummy.c
>> @@ -1044,6 +1044,8 @@ netdev_dummy_send(struct netdev *netdev, int qid OVS_UNUSED,
>>          const void *buffer = dp_packet_data(pkts[i]);
>>          size_t size = dp_packet_size(pkts[i]);
>>
>> +        size -= dp_packet_get_cutlen(pkts[i]);
>> +
>>          if (size < ETH_HEADER_LEN) {
>>              error = EMSGSIZE;
>>              break;
>> diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
>> index 82813ba..d6e5a54 100644
>> --- a/lib/netdev-linux.c
>> +++ b/lib/netdev-linux.c
>> @@ -1170,6 +1170,9 @@ netdev_linux_send(struct netdev *netdev_, int qid OVS_UNUSED,
>>          size_t size = dp_packet_size(pkts[i]);
>>          ssize_t retval;
>>
>> +        /* Truncate the packet if it is configured. */
>> +        size -= dp_packet_get_cutlen(pkts[i]);
>> +
>>          if (!is_tap_netdev(netdev_)) {
>>              /* Use our AF_PACKET socket to send to this device. */
>>              struct sockaddr_ll sll;
>> diff --git a/lib/netdev.c b/lib/netdev.c
>> index 4be806d..6651173 100644
>> --- a/lib/netdev.c
>> +++ b/lib/netdev.c
>> @@ -681,7 +681,7 @@ netdev_set_tx_multiq(struct netdev *netdev, unsigned int n_txq)
>>      return error;
>>  }
>>
>> -/* Sends 'buffers' on 'netdev'.  Returns 0 if successful (for every packet),
>> +/* Sends 'batch' on 'netdev'.  Returns 0 if successful (for every packet),
>>   * otherwise a positive errno value.  Returns EAGAIN without blocking if
>>   * at least one the packets cannot be queued immediately.  Returns EMSGSIZE
>>   * if a partial packet was transmitted or if a packet is too big or too small
>> @@ -716,6 +716,9 @@ netdev_send(struct netdev *netdev, int qid, struct dp_packet_batch *batch,
>>                                             may_steal);
>>      if (!error) {
>>          COVERAGE_INC(netdev_sent);
>> +        if (!may_steal) {
>> +            dp_packet_batch_reset_cutlen(batch);
>> +        }
>>      }
>>      return error;
>>  }
>> diff --git a/lib/odp-execute.c b/lib/odp-execute.c
>> index 4239624..5a43904 100644
>> --- a/lib/odp-execute.c
>> +++ b/lib/odp-execute.c
>> @@ -503,6 +503,7 @@ requires_datapath_assistance(const struct nlattr *a)
>>      case OVS_ACTION_ATTR_HASH:
>>      case OVS_ACTION_ATTR_PUSH_MPLS:
>>      case OVS_ACTION_ATTR_POP_MPLS:
>> +    case OVS_ACTION_ATTR_TRUNC:
>>          return false;
>>
>>      case OVS_ACTION_ATTR_UNSPEC:
>> @@ -625,6 +626,17 @@ odp_execute_actions(void *dp, struct dp_packet_batch *batch, bool steal,
>>              }
>>              break;
>>
>> +        case OVS_ACTION_ATTR_TRUNC: {
>> +            const struct ovs_action_trunc *trunc =
>> +                        nl_attr_get_unspec(a, sizeof *trunc);
>> +
>> +            batch->trunc = true;
>> +            for (i = 0; i < cnt; i++) {
>> +                dp_packet_set_cutlen(packets[i], trunc->max_len);
>> +            }
>> +            break;
>> +        }
>> +
>>          case OVS_ACTION_ATTR_OUTPUT:
>>          case OVS_ACTION_ATTR_TUNNEL_PUSH:
>>          case OVS_ACTION_ATTR_TUNNEL_POP:
>> diff --git a/lib/odp-util.c b/lib/odp-util.c
>> index 48c05f5..d7b6a2d 100644
>> --- a/lib/odp-util.c
>> +++ b/lib/odp-util.c
>> @@ -107,6 +107,7 @@ odp_action_len(uint16_t type)
>>
>>      switch ((enum ovs_action_attr) type) {
>>      case OVS_ACTION_ATTR_OUTPUT: return sizeof(uint32_t);
>> +    case OVS_ACTION_ATTR_TRUNC: return sizeof(struct ovs_action_trunc);
>>      case OVS_ACTION_ATTR_TUNNEL_PUSH: return ATTR_LEN_VARIABLE;
>>      case OVS_ACTION_ATTR_TUNNEL_POP: return sizeof(uint32_t);
>>      case OVS_ACTION_ATTR_USERSPACE: return ATTR_LEN_VARIABLE;
>> @@ -777,6 +778,14 @@ format_odp_action(struct ds *ds, const struct nlattr *a)
>>      case OVS_ACTION_ATTR_OUTPUT:
>>          ds_put_format(ds, "%"PRIu32, nl_attr_get_u32(a));
>>          break;
>> +    case OVS_ACTION_ATTR_TRUNC: {
>> +        const struct ovs_action_trunc *trunc =
>> +                       nl_attr_get_unspec(a, sizeof *trunc);
>> +
>> +        ds_put_format(ds, "trunc(%"PRIu32")", trunc->max_len);
>> +        break;
>> +    }
>> +    break;
>>      case OVS_ACTION_ATTR_TUNNEL_POP:
>>          ds_put_format(ds, "tnl_pop(%"PRIu32")", nl_attr_get_u32(a));
>>          break;
>> @@ -1528,6 +1537,20 @@ parse_odp_action(const char *s, const struct simap *port_names,
>>          }
>>      }
>>
>> +    {
>> +        uint32_t max_len;
>> +        int n;
>> +
>> +        if (ovs_scan(s, "trunc(%"SCNi32")%n", &max_len, &n)) {
>> +            struct ovs_action_trunc *trunc;
>> +
>> +            trunc = nl_msg_put_unspec_uninit(actions,
>> +                     OVS_ACTION_ATTR_TRUNC, sizeof *trunc);
>> +            trunc->max_len = max_len;
>> +            return n;
>> +        }
>> +    }
>> +
>>      if (port_names) {
>>          int len = strcspn(s, delimiters);
>>          struct simap_node *node;
>> diff --git a/lib/ofp-actions.c b/lib/ofp-actions.c
>> index ea55896..997cc15 100644
>> --- a/lib/ofp-actions.c
>> +++ b/lib/ofp-actions.c
>> @@ -301,6 +301,9 @@ enum ofp_raw_action_type {
>>      /* NX1.0+(36): struct nx_action_nat, ... */
>>      NXAST_RAW_NAT,
>>
>> +    /* NX1.0+(39): struct nx_action_output_trunc. */
>> +    NXAST_RAW_OUTPUT_TRUNC,
>> +
>>  /* ## ------------------ ## */
>>  /* ## Debugging actions. ## */
>>  /* ## ------------------ ## */
>> @@ -381,6 +384,7 @@ ofpact_next_flattened(const struct ofpact *ofpact)
>>      case OFPACT_CONTROLLER:
>>      case OFPACT_ENQUEUE:
>>      case OFPACT_OUTPUT_REG:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_BUNDLE:
>>      case OFPACT_SET_FIELD:
>>      case OFPACT_SET_VLAN_VID:
>> @@ -538,6 +542,40 @@ encode_OUTPUT(const struct ofpact_output *output,
>>  }
>>
>>  static char * OVS_WARN_UNUSED_RESULT
>> +parse_truncate_subfield(struct ofpact_output_trunc *output_trunc,
>> +                        const char *arg_)
>> +{
>> +    char *key, *value;
>> +    char *arg = CONST_CAST(char *, arg_);
>> +
>> +    while (ofputil_parse_key_value(&arg, &key, &value)) {
>> +        if (!strcmp(key, "port")) {
>> +            if (!ofputil_port_from_string(value, &output_trunc->port)) {
>> +                return xasprintf("output to unknown truncate port: %s",
>> +                                  value);
>> +            }
>> +            if (ofp_to_u16(output_trunc->port) > ofp_to_u16(OFPP_MAX)) {
>> +                if (output_trunc->port != OFPP_LOCAL &&
>> +                    output_trunc->port != OFPP_IN_PORT)
>> +                return xasprintf("output to unsupported truncate port: %s",
>> +                                 value);
>> +            }
>> +        } else if (!strcmp(key, "max_len")) {
>> +            char *err;
>> +
>> +            err = str_to_u32(value, &output_trunc->max_len);
>> +            if (err) {
>> +                return err;
>> +            }
>> +        } else {
>> +            return xasprintf("invalid key '%s' in output_trunc argument",
>> +                                key);
>> +        }
>> +    }
>> +    return NULL;
>> +}
>> +
>> +static char * OVS_WARN_UNUSED_RESULT
>>  parse_OUTPUT(const char *arg, struct ofpbuf *ofpacts,
>>               enum ofputil_protocol *usable_protocols OVS_UNUSED)
>>  {
>> @@ -547,6 +585,11 @@ parse_OUTPUT(const char *arg, struct ofpbuf *ofpacts,
>>          output_reg = ofpact_put_OUTPUT_REG(ofpacts);
>>          output_reg->max_len = UINT16_MAX;
>>          return mf_parse_subfield(&output_reg->src, arg);
>> +    } else if (strstr(arg, "port") && strstr(arg, "max_len")) {
>> +        struct ofpact_output_trunc *output_trunc;
>> +
>> +        output_trunc = ofpact_put_OUTPUT_TRUNC(ofpacts);
>> +        return parse_truncate_subfield(output_trunc, arg);
>>      } else {
>>          struct ofpact_output *output;
>>
>> @@ -5603,6 +5646,61 @@ parse_NAT(char *arg, struct ofpbuf *ofpacts,
>>      return NULL;
>>  }
>>
>> +/* Truncate output action. */
>> +struct nx_action_output_trunc {
>> +    ovs_be16 type;              /* OFPAT_VENDOR. */
>> +    ovs_be16 len;               /* At least 16. */
>> +    ovs_be32 vendor;            /* NX_VENDOR_ID. */
>> +    ovs_be16 subtype;           /* NXAST_OUTPUT_TRUNC. */
>> +    ovs_be16 port;              /* Output port */
>> +    ovs_be32 max_len;           /* Truncate packet to size bytes */
>> +};
>> +OFP_ASSERT(sizeof(struct nx_action_output_trunc) == 16);
>> +
>> +static enum ofperr
>> +decode_NXAST_RAW_OUTPUT_TRUNC(const struct nx_action_output_trunc *natrc,
>> +                            enum ofp_version ofp_version OVS_UNUSED,
>> +                            struct ofpbuf *out)
>> +{
>> +    struct ofpact_output_trunc *output_trunc;
>> +
>> +    output_trunc = ofpact_put_OUTPUT_TRUNC(out);
>> +    output_trunc->max_len = ntohl(natrc->max_len);
>> +    output_trunc->port = u16_to_ofp(ntohs(natrc->port));
>> +
>> +    if (output_trunc->max_len < ETH_HEADER_LEN) {
>> +        return OFPERR_OFPBAC_BAD_ARGUMENT;
>> +    }
>> +    return 0;
>> +}
>> +
>> +static void
>> +encode_OUTPUT_TRUNC(const struct ofpact_output_trunc *output_trunc,
>> +                  enum ofp_version ofp_version OVS_UNUSED,
>> +                  struct ofpbuf *out)
>> +{
>> +    struct nx_action_output_trunc *natrc = put_NXAST_OUTPUT_TRUNC(out);
>> +
>> +    natrc->max_len = htonl(output_trunc->max_len);
>> +    natrc->port = htons(ofp_to_u16(output_trunc->port));
>> +}
>> +
>> +static char * OVS_WARN_UNUSED_RESULT
>> +parse_OUTPUT_TRUNC(const char *arg, struct ofpbuf *ofpacts OVS_UNUSED,
>> +                 enum ofputil_protocol *usable_protocols OVS_UNUSED)
>> +{
>> +    /* Disable output_trunc parsing.  Expose as output(port=N,max_len=M) and
>> +     * reuse parse_OUTPUT to parse output_trunc action. */
>> +    return xasprintf("unknown action %s", arg);
>> +}
>> +
>> +static void
>> +format_OUTPUT_TRUNC(const struct ofpact_output_trunc *a, struct ds *s)
>> +{
>> +     ds_put_format(s, "%soutput%s(port=%"PRIu16",max_len=%"PRIu32")",
>> +                   colors.special, colors.end, a->port, a->max_len);
>> +}
>> +
>>
>>  /* Meter instruction. */
>>
>> @@ -5997,6 +6095,7 @@ ofpact_is_set_or_move_action(const struct ofpact *a)
>>      case OFPACT_NOTE:
>>      case OFPACT_OUTPUT:
>>      case OFPACT_OUTPUT_REG:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_POP_MPLS:
>>      case OFPACT_POP_QUEUE:
>>      case OFPACT_PUSH_MPLS:
>> @@ -6025,6 +6124,7 @@ ofpact_is_allowed_in_actions_set(const struct ofpact *a)
>>      case OFPACT_DEC_TTL:
>>      case OFPACT_GROUP:
>>      case OFPACT_OUTPUT:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_POP_MPLS:
>>      case OFPACT_PUSH_MPLS:
>>      case OFPACT_PUSH_VLAN:
>> @@ -6249,6 +6349,7 @@ ovs_instruction_type_from_ofpact_type(enum ofpact_type type)
>>      case OFPACT_CONTROLLER:
>>      case OFPACT_ENQUEUE:
>>      case OFPACT_OUTPUT_REG:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_BUNDLE:
>>      case OFPACT_SET_VLAN_VID:
>>      case OFPACT_SET_VLAN_PCP:
>> @@ -6677,6 +6778,10 @@ ofpact_check__(enum ofputil_protocol *usable_protocols, struct ofpact *a,
>>      case OFPACT_OUTPUT_REG:
>>          return mf_check_src(&ofpact_get_OUTPUT_REG(a)->src, flow);
>>
>> +    case OFPACT_OUTPUT_TRUNC:
>> +        return ofpact_check_output_port(ofpact_get_OUTPUT_TRUNC(a)->port,
>> +                                        max_ports);
>> +
>>      case OFPACT_BUNDLE:
>>          return bundle_check(ofpact_get_BUNDLE(a), max_ports, flow);
>>
>> @@ -7354,6 +7459,7 @@ ofpact_outputs_to_port(const struct ofpact *ofpact, ofp_port_t port)
>>          return port == OFPP_CONTROLLER;
>>
>>      case OFPACT_OUTPUT_REG:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_BUNDLE:
>>      case OFPACT_SET_VLAN_VID:
>>      case OFPACT_SET_VLAN_PCP:
>> diff --git a/ofproto/ofproto-dpif-sflow.c b/ofproto/ofproto-dpif-sflow.c
>> index fbc82b7..5d26b7c 100644
>> --- a/ofproto/ofproto-dpif-sflow.c
>> +++ b/ofproto/ofproto-dpif-sflow.c
>> @@ -1140,6 +1140,7 @@ dpif_sflow_read_actions(const struct flow *flow,
>>             }
>>             break;
>>
>> +       case OVS_ACTION_ATTR_TRUNC:
>>         case OVS_ACTION_ATTR_USERSPACE:
>>         case OVS_ACTION_ATTR_RECIRC:
>>         case OVS_ACTION_ATTR_HASH:
>> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
>> index f8c4a93..d46a52c 100644
>> --- a/ofproto/ofproto-dpif-xlate.c
>> +++ b/ofproto/ofproto-dpif-xlate.c
>> @@ -3995,6 +3995,56 @@ xlate_output_reg_action(struct xlate_ctx *ctx,
>>  }
>>
>>  static void
>> +xlate_output_trunc_action(struct xlate_ctx *ctx,
>> +                    ofp_port_t port, uint32_t max_len)
>> +{
>> +    bool support_trunc = ctx->xbridge->support.trunc;
>> +    struct ovs_action_trunc *trunc;
>> +    char name[OFP_MAX_PORT_NAME_LEN];
>> +
>> +    switch (port) {
>> +    case OFPP_TABLE:
>> +    case OFPP_NORMAL:
>> +    case OFPP_FLOOD:
>> +    case OFPP_ALL:
>> +    case OFPP_CONTROLLER:
>> +    case OFPP_NONE:
>> +        ofputil_port_to_string(port, name, sizeof name);
>> +        xlate_report(ctx, "output_trunc does not support port: %s", name);
>> +        break;
>> +    case OFPP_LOCAL:
>> +    case OFPP_IN_PORT:
>> +    default:
>> +        if (port != ctx->xin->flow.in_port.ofp_port) {
>> +            const struct xport *xport = get_ofp_port(ctx->xbridge, port);
>> +
>> +            if (xport == NULL || xport->odp_port == ODPP_NONE) {
>> +                /* Since truncate happens at its following output action, if
>> +                 * the output port is a patch port, the behavior is somehow
>> +                 * unpredicable. For simpilicity, disallow this case. */
>> +                ofputil_port_to_string(port, name, sizeof name);
>> +                XLATE_REPORT_ERROR(ctx, "bridge %s: "
>> +                         "output_trunc does not support port: %s",
>> +                         ctx->xbridge->name, name);
>> +                break;
>> +            }
>> +
>> +            trunc = nl_msg_put_unspec_uninit(ctx->odp_actions,
>> +                                OVS_ACTION_ATTR_TRUNC,
>> +                                sizeof *trunc);
>> +            trunc->max_len = max_len;
>> +            xlate_output_action(ctx, port, max_len, false);
>> +            if (!support_trunc) {
>> +                ctx->xout->slow |= SLOW_ACTION;
>> +            }
>> +        } else {
>> +            xlate_report(ctx, "skipping output to input port");
>> +        }
>> +        break;
>> +    }
>> +}
>> +
>> +static void
>>  xlate_enqueue_action(struct xlate_ctx *ctx,
>>                       const struct ofpact_enqueue *enqueue)
>>  {
>> @@ -4333,6 +4383,7 @@ freeze_unroll_actions(const struct ofpact *a, const struct ofpact *end,
>>      for (; a < end; a = ofpact_next(a)) {
>>          switch (a->type) {
>>          case OFPACT_OUTPUT_REG:
>> +        case OFPACT_OUTPUT_TRUNC:
>>          case OFPACT_GROUP:
>>          case OFPACT_OUTPUT:
>>          case OFPACT_CONTROLLER:
>> @@ -4584,6 +4635,7 @@ recirc_for_mpls(const struct ofpact *a, struct xlate_ctx *ctx)
>>
>>      /* Output actions  do not require recirculation. */
>>      case OFPACT_OUTPUT:
>> +    case OFPACT_OUTPUT_TRUNC:
>>      case OFPACT_ENQUEUE:
>>      case OFPACT_OUTPUT_REG:
>>      /* Set actions that don't touch L3+ fields do not require recirculation. */
>> @@ -4933,6 +4985,11 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
>>              xlate_output_reg_action(ctx, ofpact_get_OUTPUT_REG(a));
>>              break;
>>
>> +        case OFPACT_OUTPUT_TRUNC:
>> +            xlate_output_trunc_action(ctx, ofpact_get_OUTPUT_TRUNC(a)->port,
>> +                                ofpact_get_OUTPUT_TRUNC(a)->max_len);
>> +            break;
>> +
>>          case OFPACT_LEARN:
>>              xlate_learn_action(ctx, ofpact_get_LEARN(a));
>>              break;
>> diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
>> index 100e8d5..0cd1c25 100644
>> --- a/ofproto/ofproto-dpif.c
>> +++ b/ofproto/ofproto-dpif.c
>> @@ -1212,6 +1212,63 @@ check_masked_set_action(struct dpif_backer *backer)
>>      return !error;
>>  }
>>
>> +/* Tests whether 'backer''s datapath supports truncation of a packet in
>> + * OVS_ACTION_ATTR_TRUNC.  We need to disable some features on older
>> + * datapaths that don't support this feature. */
>> +static bool
>> +check_trunc_action(struct dpif_backer *backer)
>> +{
>> +    struct eth_header *eth;
>> +    struct ofpbuf actions;
>> +    struct dpif_execute execute;
>> +    struct dp_packet packet;
>> +    struct ovs_action_trunc *trunc;
>> +    struct flow flow;
>> +    int error;
>> +
>> +    /* Compose an action with output(port:1,
>> +     *              max_len:OVS_ACTION_OUTPUT_MIN + 1).
>> +     * This translates to one truncate action and one output action. */
>> +    ofpbuf_init(&actions, 64);
>> +    trunc = nl_msg_put_unspec_uninit(&actions,
>> +                            OVS_ACTION_ATTR_TRUNC, sizeof *trunc);
>> +
>> +    trunc->max_len = ETH_HEADER_LEN + 1;
>> +    nl_msg_put_odp_port(&actions, OVS_ACTION_ATTR_OUTPUT, u32_to_odp(1));
>> +
>> +    /* Compose a dummy Ethernet packet. */
>> +    dp_packet_init(&packet, ETH_HEADER_LEN);
>> +    eth = dp_packet_put_zeros(&packet, ETH_HEADER_LEN);
>> +    eth->eth_type = htons(0x1234);
>> +
>> +    flow_extract(&packet, &flow);
>> +
>> +    /* Execute the actions.  On older datapaths this fails with EINVAL, on
>> +     * newer datapaths it succeeds. */
>> +    execute.actions = actions.data;
>> +    execute.actions_len = actions.size;
>> +    execute.packet = &packet;
>> +    execute.flow = &flow;
>> +    execute.needs_help = false;
>> +    execute.probe = true;
>> +    execute.mtu = 0;
>> +
>> +    error = dpif_execute(backer->dpif, &execute);
>> +
>> +    dp_packet_uninit(&packet);
>> +    ofpbuf_uninit(&actions);
>> +
>> +    if (error) {
>> +        VLOG_INFO("%s: Datapath does not support truncate action",
>> +                  dpif_name(backer->dpif));
>> +    } else {
>> +        VLOG_INFO("%s: Datapath supports truncate action",
>> +                  dpif_name(backer->dpif));
>> +    }
>> +
>> +    return !error;
>> +}
>> +
>>  #define CHECK_FEATURE__(NAME, SUPPORT, FIELD, VALUE)                        \
>>  static bool                                                                 \
>>  check_##NAME(struct dpif_backer *backer)                                    \
>> @@ -1263,6 +1320,7 @@ check_support(struct dpif_backer *backer)
>>      backer->support.odp.recirc = check_recirc(backer);
>>      backer->support.odp.max_mpls_depth = check_max_mpls_depth(backer);
>>      backer->support.masked_set_action = check_masked_set_action(backer);
>> +    backer->support.trunc = check_trunc_action(backer);
>>      backer->support.ufid = check_ufid(backer);
>>      backer->support.tnl_push_pop = dpif_supports_tnl_push_pop(backer->dpif);
>>
>> @@ -5343,6 +5401,24 @@ disable_tnl_push_pop(struct unixctl_conn *conn OVS_UNUSED, int argc OVS_UNUSED,
>>  }
>>
>>  static void
>> +disable_datapath_truncate(struct unixctl_conn *conn OVS_UNUSED,
>> +                          int argc OVS_UNUSED,
>> +                          const char *argv[] OVS_UNUSED,
>> +                          void *aux OVS_UNUSED)
>> +{
>> +    const struct shash_node **backers;
>> +    int i;
>> +
>> +    backers = shash_sort(&all_dpif_backers);
>> +    for (i = 0; i < shash_count(&all_dpif_backers); i++) {
>> +        struct dpif_backer *backer = backers[i]->data;
>> +        backer->support.trunc = false;
>> +    }
>> +    free(backers);
>> +    unixctl_command_reply(conn, "Datapath truncate action diabled");
>> +}
>> +
>> +static void
>>  ofproto_unixctl_init(void)
>>  {
>>      static bool registered;
>> @@ -5376,6 +5452,9 @@ ofproto_unixctl_init(void)
>>
>>      unixctl_command_register("ofproto/tnl-push-pop", "[on]|[off]", 1, 1,
>>                               disable_tnl_push_pop, NULL);
>> +
>> +    unixctl_command_register("dpif/disable-truncate", "", 0, 0,
>> +                             disable_datapath_truncate, NULL);
>>  }
>>
>>  /* Returns true if 'table' is the table used for internal rules,
>> diff --git a/ofproto/ofproto-dpif.h b/ofproto/ofproto-dpif.h
>> index 9e03b01..4034475 100644
>> --- a/ofproto/ofproto-dpif.h
>> +++ b/ofproto/ofproto-dpif.h
>> @@ -90,6 +90,9 @@ struct dpif_backer_support {
>>      /* True if the datapath supports OVS_FLOW_ATTR_UFID. */
>>      bool ufid;
>>
>> +    /* True if the datapath supports OVS_ACTION_ATTR_TRUNC action. */
>> +    bool trunc;
>> +
>>      /* Each member represents support for related OVS_KEY_ATTR_* fields. */
>>      struct odp_support odp;
>>  };
>> diff --git a/tests/odp.at b/tests/odp.at
>> index 7b94c92..e630855 100644
>> --- a/tests/odp.at
>> +++ b/tests/odp.at
>> @@ -329,6 +329,7 @@ ct(commit,nat(src=fe80::20c:29ff:fe88:a18b,random))
>>  ct(commit,nat(src=fe80::20c:29ff:fe88:1-fe80::20c:29ff:fe88:a18b,random))
>>  ct(commit,nat(src=[[fe80::20c:29ff:fe88:1]]-[[fe80::20c:29ff:fe88:a18b]]:255-4096,random))
>>  ct(commit,helper=ftp,nat(src=10.1.1.240-10.1.1.255))
>> +trunc(100)
>>  ])
>>  AT_CHECK_UNQUOTED([ovstest test-odp parse-actions < actions.txt], [0],
>>    [`cat actions.txt`
>> diff --git a/tests/ofp-actions.at b/tests/ofp-actions.at
>> index 50f74e9..ca4d1ba 100644
>> --- a/tests/ofp-actions.at
>> +++ b/tests/ofp-actions.at
>> @@ -241,6 +241,9 @@ fe800000 00000000 020c 29ff fe88 0001 dnl
>>  fe800000 00000000 020c 29ff fe88 a18b dnl
>>  00ff1000 00000000
>>
>> +# actions=output(port=1,max_len=100)
>> +ffff 0010 00002320 0027 0001 00000064
>> +
>>  # bad OpenFlow10 actions: NXBRC_MUST_BE_ZERO
>>  ffff 0018 00002320 0025 0000 0005 0000 1122334455 000005
>>
>> diff --git a/tests/ofproto-dpif.at b/tests/ofproto-dpif.at
>> index 9b94f3d..b0c6e0a 100644
>> --- a/tests/ofproto-dpif.at
>> +++ b/tests/ofproto-dpif.at
>> @@ -5322,6 +5322,130 @@ PORTNAME
>>         portName=p2
>>  ])])
>>
>> +AT_SETUP([ofproto-dpif - basic truncate action])
>> +OVS_VSWITCHD_START
>> +add_of_ports br0 1 2 3 4 5
>> +
>> +AT_CHECK([ovs-vsctl -- set Interface p1 type=dummy options:pcap=p1.pcap])
>> +AT_CHECK([ovs-vsctl -- set Interface p2 type=dummy options:pstream=punix:p2.sock])
>> +AT_CHECK([ovs-vsctl -- set Interface p3 type=dummy   options:stream=unix:p2.sock])
>> +AT_CHECK([ovs-vsctl -- set Interface p4 type=dummy options:pstream=punix:p4.sock])
>> +AT_CHECK([ovs-vsctl -- set Interface p5 type=dummy   options:stream=unix:p4.sock])
>> +
>> +AT_DATA([flows.txt], [dnl
>> +in_port=3,actions=drop
>> +in_port=5,actions=drop
>> +in_port=1,actions=output(port=2,max_len=64),output:4
>> +])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +dnl Datapath actions
>> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
>> +AT_CHECK([tail -1 stdout], [0],
>> +[Datapath actions: trunc(64),2,4
>> +])
>> +
>> +dnl An 170 byte packet
>> +AT_CHECK([ovs-appctl netdev-dummy/receive p1 '000c29c8a0a4005056c0000808004500009cb4a6000040019003c0a8da01c0a8da640800cb5fa762000556f431ad0009388e08090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f'])
>> +
>> +AT_CHECK([ovs-ofctl parse-pcap p1.pcap], [0], [dnl
>> +icmp,in_port=ANY,vlan_tci=0x0000,dl_src=00:50:56:c0:00:08,dl_dst=00:0c:29:c8:a0:a4,nw_src=192.168.218.1,nw_dst=192.168.218.100,nw_tos=0,nw_ecn=0,nw_ttl=64,icmp_type=8,icmp_code=0
>> +])
>> +
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +dnl packet with truncated size
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=64
>> +])
>> +dnl packet with original size
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=170
>> +])
>> +
>> +dnl More complicated case
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_DATA([flows.txt], [dnl
>> +in_port=3,actions=drop
>> +in_port=5,actions=drop
>> +in_port=1,actions=output(port=2,max_len=64),output(port=2,max_len=128),output(port=4,max_len=60),output:2,output:4
>> +])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +dnl Datapath actions
>> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
>> +AT_CHECK([tail -1 stdout], [0],
>> +[Datapath actions: trunc(64),2,trunc(128),2,trunc(60),4,2,4
>> +])
>> +
>> +dnl An 170 byte packet
>> +AT_CHECK([ovs-appctl netdev-dummy/receive p1 '000c29c8a0a4005056c0000808004500009cb4a6000040019003c0a8da01c0a8da640800cb5fa762000556f431ad0009388e08090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f'])
>> +
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +dnl packet size: 64 + 128 + 170 = 362
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=362
>> +])
>> +dnl packet size: 60 + 170 = 230
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=230
>> +])
>> +
>> +dnl syntax checking
>> +AT_CHECK([ovs-ofctl add-flow br0 'actions=output(port=ALL,max_len=100)'], [1], [], [dnl
>> +ovs-ofctl: output to unsupported truncate port: ALL
>> +])
>> +
>> +OVS_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>> +AT_SETUP([ofproto-dpif - truncate and output to patch port])
>> +OVS_VSWITCHD_START([add-br br1 \
>> +-- set bridge br1 datapath-type=dummy fail-mode=secure \
>> +-- add-port br1 pbr1 -- set int pbr1 type=patch options:peer=pbr0 ofport_request=1 \
>> +-- add-port br0 pbr0 -- set int pbr0 type=patch options:peer=pbr1])
>> +
>> +add_of_ports br0 2
>> +
>> +AT_CHECK([ovs-ofctl add-flow br0 actions='output(port=1,max_len=100),output:2'])
>> +AT_CHECK([ovs-ofctl add-flow br1 actions=NORMAL])
>> +
>> +AT_CHECK([ovs-appctl ofproto/trace br0 in_port=LOCAL,dl_src=10:20:30:40:50:60],
>> +[0], [stdout])
>> +AT_CHECK([tail -1 stdout], [0], [Datapath actions: 2
>> +])
>> +dnl the output(port=1,max_len=100) fails the translation, only output:2 in datapath
>> +AT_CHECK([grep "output_trunc does not support port: [[0-9]]*" stdout], [0], [stdout])
>> +
>> +OVS_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>> +AT_SETUP([ofproto-dpif - truncate and output to gre tunnel])
>> +OVS_VSWITCHD_START([add-port br0 p1 -- set Interface p1 type=gre \
>> +                    options:remote_ip=1.1.1.1 options:local_ip=2.2.2.2 \
>> +                    options:key=5 ofport_request=1\
>> +                    -- add-port br0 p2 -- set Interface p2 type=dummy \
>> +                    ofport_request=2])
>> +AT_DATA([flows.txt], [dnl
>> +actions=output(max_len=100, port=1)
>> +])
>> +OVS_VSWITCHD_DISABLE_TUNNEL_PUSH_POP
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +AT_CHECK([ovs-appctl dpif/show | tail -n +3], [0], [dnl
>> +               br0 65534/100: (dummy)
>> +               p1 1/1: (gre: key=5, local_ip=2.2.2.2, remote_ip=1.1.1.1)
>> +               p2 2/2: (dummy)
>> +])
>> +
>> +dnl Basic
>> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(2),eth(src=50:54:00:00:00:05,dst=50:54:00:00:00:07),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
>> +AT_CHECK([tail -1 stdout], [0],
>> +  [Datapath actions: trunc(100),set(tunnel(tun_id=0x5,src=2.2.2.2,dst=1.1.1.1,ttl=64,flags(df|key))),1
>> +])
>> +
>> +OVS_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>>  AT_SETUP([ofproto-dpif - sFlow packet sampling - IPv4 collector])
>>  CHECK_SFLOW_SAMPLING_PACKET([127.0.0.1])
>>  AT_CLEANUP
>> diff --git a/tests/ovs-ofctl.at b/tests/ovs-ofctl.at
>> index 613d9ce..71c4aab 100644
>> --- a/tests/ovs-ofctl.at
>> +++ b/tests/ovs-ofctl.at
>> @@ -388,6 +388,10 @@ ip,actions=ct(commit,exec(load(0x1->NXM_NX_CT_LABEL[])))
>>  ip,actions=ct(commit,exec(load(0x1234567890ABCDEF->NXM_NX_CT_LABEL[32..95])))
>>  ip,actions=ct(commit,exec(set_field(0x1->ct_label)))
>>  ip,ct_state=+trk,ct_label=0x1234567890abcdef12345678,actions=ct(commit)
>> +actions=output(max_len=100,port=123)
>> +actions=output(port=100,max_len=123)
>> +actions=output(port=LOCAL,max_len=123)
>> +actions=output(port=IN_PORT,max_len=123)
>>  ]])
>>
>>  AT_CHECK([ovs-ofctl parse-flows flows.txt
>> @@ -431,6 +435,10 @@ NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1->NXM_NX_CT_LABEL[
>>  NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1234567890abcdef->NXM_NX_CT_LABEL[32..95]))
>>  NXT_FLOW_MOD: ADD table:255 ip actions=ct(commit,exec(load:0x1->NXM_NX_CT_LABEL[0..63],load:0->NXM_NX_CT_LABEL[64..127]))
>>  NXT_FLOW_MOD: ADD table:255 ct_state=+trk,ct_label=0x1234567890abcdef12345678,ip actions=ct(commit)
>> +NXT_FLOW_MOD: ADD table:255 actions=output(port=123,max_len=100)
>> +NXT_FLOW_MOD: ADD table:255 actions=output(port=100,max_len=123)
>> +NXT_FLOW_MOD: ADD table:255 actions=output(port=65534,max_len=123)
>> +NXT_FLOW_MOD: ADD table:255 actions=output(port=65528,max_len=123)
>>  ]])
>>  AT_CLEANUP
>>
>> diff --git a/tests/system-kmod-macros.at b/tests/system-kmod-macros.at
>> index cee0510..a3e4dd7 100644
>> --- a/tests/system-kmod-macros.at
>> +++ b/tests/system-kmod-macros.at
>> @@ -66,3 +66,10 @@ m4_define([CHECK_CONNTRACK],
>>       on_exit 'ovstest test-netlink-conntrack flush'
>>      ]
>>  )
>> +
>> +# CHECK_KERNEL_DP, CHECK_USER_DP
>> +#
>> +# Ignore the CHECK_USER_DP and execute the CHECK_KERNEL_DP
>> +#
>> +m4_define([CHECK_KERNEL_DP], [$1])
>> +m4_define([CHECK_USER_DP], [])
>> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
>> index 5ce3955..606bc9b 100644
>> --- a/tests/system-traffic.at
>> +++ b/tests/system-traffic.at
>> @@ -250,6 +250,253 @@ NS_CHECK_EXEC([at_ns0], [ping -s 3200 -q -c 3 -i 0.3 -w 2 10.1.1.100 | FORMAT_PI
>>  OVS_TRAFFIC_VSWITCHD_STOP
>>  AT_CLEANUP
>>
>> +AT_SETUP([datapath - basic truncate action])
>> +OVS_TRAFFIC_VSWITCHD_START()
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +
>> +dnl Create p0 and ovs-p0(1)
>> +ADD_NAMESPACES(at_ns0)
>> +ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24")
>> +NS_CHECK_EXEC([at_ns0], [ip link set dev p0 address e6:66:c1:11:11:11])
>> +NS_CHECK_EXEC([at_ns0], [arp -s 10.1.1.2 e6:66:c1:22:22:22])
>> +
>> +dnl Create p1(3) and ovs-p1(2), packets received from ovs-p1 will appear in p1
>> +AT_CHECK([ip link add p1 type veth peer name ovs-p1])
>> +on_exit 'ip link del ovs-p1'
>> +AT_CHECK([ip link set dev ovs-p1 up])
>> +AT_CHECK([ip link set dev p1 up])
>> +AT_CHECK([ovs-vsctl add-port br0 ovs-p1 -- set interface ovs-p1 ofport_request=2])
>> +dnl Use p1 to check the truncated packet
>> +AT_CHECK([ovs-vsctl add-port br0 p1 -- set interface p1 ofport_request=3])
>> +
>> +dnl Create p2(5) and ovs-p2(4)
>> +AT_CHECK([ip link add p2 type veth peer name ovs-p2])
>> +on_exit 'ip link del ovs-p2'
>> +AT_CHECK([ip link set dev ovs-p2 up])
>> +AT_CHECK([ip link set dev p2 up])
>> +AT_CHECK([ovs-vsctl add-port br0 ovs-p2 -- set interface ovs-p2 ofport_request=4])
>> +dnl Use p2 to check the truncated packet
>> +AT_CHECK([ovs-vsctl add-port br0 p2 -- set interface p2 ofport_request=5])
>> +
>> +dnl basic test
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_DATA([flows.txt], [dnl
>> +in_port=3 dl_dst=e6:66:c1:22:22:22 actions=drop
>> +in_port=5 dl_dst=e6:66:c1:22:22:22 actions=drop
>> +in_port=1 dl_dst=e6:66:c1:22:22:22 actions=output(port=2,max_len=100),output:4
>> +])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +dnl use this file as payload file for ncat
>> +AT_CHECK([dd if=/dev/urandom of=payload200.bin bs=200 count=1 2> /dev/null])
>> +on_exit 'rm -f payload200.bin'
>> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
>> +
>> +dnl packet with truncated size
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" |  sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=100
>> +])
>> +dnl packet with original size
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=242
>> +])
>> +
>> +dnl more complicated output actions
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_DATA([flows.txt], [dnl
>> +in_port=3 dl_dst=e6:66:c1:22:22:22 actions=drop
>> +in_port=5 dl_dst=e6:66:c1:22:22:22 actions=drop
>> +in_port=1 dl_dst=e6:66:c1:22:22:22 actions=output(port=2,max_len=100),output:4,output(port=2,max_len=100),output(port=4,max_len=100),output:2,output(port=4,max_len=200),output(port=2,max_len=65535)
>> +])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
>> +
>> +dnl 100 + 100 + 242 + min(65535,242) = 684
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=684
>> +])
>> +dnl 242 + 100 + min(242,200) = 542
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=542
>> +])
>> +
>> +dnl SLOW_ACTION: disable kernel datapath truncate support
>> +dnl Repeat the test above, but exercise the SLOW_ACTION code path
>> +AT_CHECK([ovs-appctl dpif/disable-truncate], [0],
>> +[Datapath truncate action diabled
>> +])
>> +
>> +dnl SLOW_ACTION test1: check datapatch actions
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +CHECK_KERNEL_DP(
>> +AT_CHECK([ovs-appctl ofproto/trace system 'in_port(2),eth(src=e6:66:c1:11:11:11,dst=e6:66:c1:22:22:22),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=6,tos=4,ttl=128,frag=no),tcp(src=8,dst=9)'], [0], [stdout])
>> +AT_CHECK([tail -3 stdout], [0],
>> +[Datapath actions: trunc(100),3,5,trunc(100),3,trunc(100),5,3,trunc(200),5,trunc(65535),3
>> +This flow is handled by the userspace slow path because it:
>> +       - Uses action(s) not supported by datapath.
>> +])
>> +)
>> +
>> +dnl SLOW_ACTION test2: check actual packet truncate
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 1234 < payload200.bin])
>> +
>> +dnl 100 + 100 + 242 + min(65535,242) = 684
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=3" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=684
>> +])
>> +
>> +dnl 242 + 100 + min(242,200) = 542
>> +AT_CHECK([ovs-ofctl dump-flows br0 table=0 | grep "in_port=5" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=542
>> +])
>> +
>> +OVS_TRAFFIC_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>> +dnl Create 2 bridges and 2 namespaces to test truncate over
>> +dnl GRE tunnel:
>> +dnl   br0: overlay bridge
>> +dnl   ns1: connect to br0, with IP:10.1.1.2
>> +dnl   br-underlay: with IP: 172.31.1.100
>> +dnl   ns0: connect to br-underlay, with IP: 10.1.1.1
>> +AT_SETUP([datapath - truncate and output to gre tunnel])
>> +OVS_CHECK_GRE()
>> +OVS_TRAFFIC_VSWITCHD_START()
>> +
>> +ADD_BR([br-underlay])
>> +ADD_NAMESPACES(at_ns0)
>> +ADD_NAMESPACES(at_ns1)
>> +AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
>> +AT_CHECK([ovs-ofctl add-flow br-underlay "actions=normal"])
>> +
>> +dnl Set up underlay link from host into the namespace using veth pair.
>> +ADD_VETH(p0, at_ns0, br-underlay, "172.31.1.1/24")
>> +AT_CHECK([ip addr add dev br-underlay "172.31.1.100/24"])
>> +AT_CHECK([ip link set dev br-underlay up])
>> +
>> +dnl Set up tunnel endpoints on OVS outside the namespace and with a native
>> +dnl linux device inside the namespace.
>> +ADD_OVS_TUNNEL([gre], [br0], [at_gre0], [172.31.1.1], [10.1.1.100/24])
>> +ADD_NATIVE_TUNNEL([gretap], [ns_gre0], [at_ns0], [172.31.1.100], [10.1.1.1/24])
>> +AT_CHECK([ovs-vsctl -- set interface at_gre0 ofport_request=1])
>> +NS_CHECK_EXEC([at_ns0], [ip link set dev ns_gre0 address e6:66:c1:11:11:11])
>> +NS_CHECK_EXEC([at_ns0], [arp -s 10.1.1.2 e6:66:c1:22:22:22])
>> +
>> +dnl Set up (p1 and ovs-p1) at br0
>> +ADD_VETH(p1, at_ns1, br0, '10.1.1.2/24')
>> +AT_CHECK([ovs-vsctl -- set interface ovs-p1 ofport_request=2])
>> +NS_CHECK_EXEC([at_ns1], [ip link set dev p1 address e6:66:c1:22:22:22])
>> +NS_CHECK_EXEC([at_ns1], [arp -s 10.1.1.1 e6:66:c1:11:11:11])
>> +
>> +dnl Set up (p2 and ovs-p2) as loopback for verifying packet size
>> +AT_CHECK([ip link add p2 type veth peer name ovs-p2])
>> +on_exit 'ip link del ovs-p2'
>> +AT_CHECK([ip link set dev ovs-p2 up])
>> +AT_CHECK([ip link set dev p2 up])
>> +AT_CHECK([ovs-vsctl add-port br0 ovs-p2 -- set interface ovs-p2 ofport_request=3])
>> +AT_CHECK([ovs-vsctl add-port br0 p2 -- set interface p2 ofport_request=4])
>> +
>> +dnl use this file as payload file for ncat
>> +AT_CHECK([dd if=/dev/urandom of=payload200.bin bs=200 count=1 2> /dev/null])
>> +on_exit 'rm -f payload200.bin'
>> +
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_DATA([flows.txt], [dnl
>> +priority=99,in_port=1,actions=output(port=2,max_len=100),output(port=3,max_len=100)
>> +priority=99,in_port=2,udp,actions=output(port=1,max_len=100)
>> +priority=1,in_port=4,ip,actions=drop
>> +priority=1,actions=drop
>> +])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +AT_CHECK([ovs-ofctl del-flows br-underlay])
>> +AT_DATA([flows-underlay.txt], [dnl
>> +priority=99,dl_type=0x0800,nw_proto=47,in_port=1,actions=LOCAL
>> +priority=99,dl_type=0x0800,nw_proto=47,in_port=LOCAL,ip_dst=172.31.1.1/24,actions=1
>> +priority=1,actions=drop
>> +])
>> +
>> +AT_CHECK([ovs-ofctl add-flows br-underlay flows-underlay.txt])
>> +
>> +dnl check tunnel push path, from at_ns1 to at_ns0
>> +NS_CHECK_EXEC([at_ns1], [nc -u 10.1.1.1 1234 < payload200.bin])
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +
>> +dnl Before truncation = ETH(14) + IP(20) + UDP(8) + 200 = 242B
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=2" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=242
>> +])
>> +dnl After truncation = outer ETH(14) + outer IP(20) + GRE(4) + 100 = 138B
>> +AT_CHECK([ovs-ofctl dump-flows br-underlay | grep "in_port=LOCAL" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=138
>> +])
>> +
>> +dnl check tunnel pop path, from at_ns0 to at_ns1
>> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 5678 < payload200.bin])
>> +dnl After truncation = 100 byte at loopback device p2(4)
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=4" | awk --field-separator=', '  '{print $5}'], [0], [dnl
>> +n_bytes=100
>> +])
>> +
>> +dnl SLOW_ACTION: disable datapath truncate support
>> +dnl Repeat the test above, but exercise the SLOW_ACTION code path
>> +AT_CHECK([ovs-appctl dpif/disable-truncate], [0],
>> +[Datapath truncate action diabled
>> +])
>> +
>> +dnl SLOW_ACTION test1: check datapatch actions
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +
>> +CHECK_KERNEL_DP(
>> +AT_CHECK([ovs-appctl ofproto/trace system 'in_port(5),eth(src=e6:66:c1:11:11:11,dst=e6:66:c1:22:22:22),eth_type(0x0800),ipv4(src=192.168.0.1,dst=192.168.0.2,proto=17,tos=4,ttl=128,frag=no),udp(src=8,dst=9)'], [0], [stdout])
>> +AT_CHECK([tail -3 stdout], [0],
>> +[Datapath actions: trunc(100),set(tunnel(dst=172.31.1.1,ttl=64,flags(df))),4
>> +This flow is handled by the userspace slow path because it:
>> +       - Uses action(s) not supported by datapath.
>> +])
>> +)
>> +
>> +dnl SLOW_ACTION test2: check actual packet truncate
>> +AT_CHECK([ovs-ofctl del-flows br0])
>> +AT_CHECK([ovs-ofctl add-flows br0 flows.txt])
>> +AT_CHECK([ovs-ofctl del-flows br-underlay])
>> +AT_CHECK([ovs-ofctl add-flows br-underlay flows-underlay.txt])
>> +
>> +dnl check tunnel push path, from at_ns1 to at_ns0
>> +NS_CHECK_EXEC([at_ns1], [nc -u 10.1.1.1 1234 < payload200.bin])
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +
>> +dnl Before truncation = ETH(14) + IP(20) + UDP(8) + 200 = 242B
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=2" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=242
>> +])
>> +dnl After truncation = outer ETH(14) + outer IP(20) + GRE(4) + 100 = 138B
>> +AT_CHECK([ovs-ofctl dump-flows br-underlay | grep "in_port=LOCAL" | sed -n 's/.*\(n\_bytes=[[0-9]]*\).*/\1/p'], [0], [dnl
>> +n_bytes=138
>> +])
>> +
>> +dnl check tunnel pop path, from at_ns0 to at_ns1
>> +NS_CHECK_EXEC([at_ns0], [nc -u 10.1.1.2 5678 < payload200.bin])
>> +dnl After truncation = 100 byte at loopback device p2(4)
>> +AT_CHECK([ovs-appctl revalidator/purge], [0])
>> +AT_CHECK([ovs-ofctl dump-flows br0 | grep "in_port=4" | awk --field-separator=', '  '{print $5}'], [0], [dnl
>> +n_bytes=100
>> +])
>> +
>> +OVS_TRAFFIC_VSWITCHD_STOP
>> +AT_CLEANUP
>> +
>>  AT_SETUP([conntrack - controller])
>>  CHECK_CONNTRACK()
>>  OVS_TRAFFIC_VSWITCHD_START()
>> diff --git a/tests/system-userspace-macros.at b/tests/system-userspace-macros.at
>> index c09a4aa..dc4bd0e 100644
>> --- a/tests/system-userspace-macros.at
>> +++ b/tests/system-userspace-macros.at
>> @@ -66,3 +66,10 @@ m4_define([CONFIGURE_VETH_OFFLOADS],
>>  m4_define([CHECK_CONNTRACK],
>>      [AT_SKIP_IF(true)]
>>  )
>> +
>> +# CHECK_KERNEL_DP, CHECK_USER_DP
>> +#
>> +# Ignore the CHECK_KERNEL_DP and execute the CHECK_USER_DP
>> +#
>> +m4_define([CHECK_KERNEL_DP], [])
>> +m4_define([CHECK_USER_DP], [$1])
>> --
> Test looks good.
>
> packet truncate support documentation is missing in man page. NEWS
> also needs to be updated.