@@ -677,7 +677,7 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk)
/* In most cases we will be able to lock the mptcp socket. If its already
* owned, we need to defer to the work queue to avoid ABBA deadlock.
*/
-static void move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
+static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
{
struct sock *sk = (struct sock *)msk;
unsigned int moved = 0;
@@ -698,6 +698,8 @@ static void move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
if (mptcp_pending_data_fin(sk, NULL))
mptcp_schedule_work(sk);
mptcp_data_unlock(sk);
+
+ return moved > 0;
}
void mptcp_data_ready(struct sock *sk, struct sock *ssk)
@@ -705,7 +707,6 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
struct mptcp_sock *msk = mptcp_sk(sk);
int sk_rbuf, ssk_rbuf;
- bool wake;
/* The peer can send data while we are shutting down this
* subflow at msk destruction time, but we must avoid enqueuing
@@ -714,28 +715,20 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
if (unlikely(subflow->disposable))
return;
- /* move_skbs_to_msk below can legitly clear the data_avail flag,
- * but we will need later to properly woke the reader, cache its
- * value
- */
- wake = subflow->data_avail == MPTCP_SUBFLOW_DATA_AVAIL;
- if (wake)
- set_bit(MPTCP_DATA_READY, &msk->flags);
-
ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
if (unlikely(ssk_rbuf > sk_rbuf))
sk_rbuf = ssk_rbuf;
- /* over limit? can't append more skbs to msk */
+ /* over limit? can't append more skbs to msk, Also, no need to wake-up*/
if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf)
- goto wake;
-
- move_skbs_to_msk(msk, ssk);
+ return;
-wake:
- if (wake)
+ /* Wake-up the reader only for in-sequence data */
+ if (move_skbs_to_msk(msk, ssk)) {
+ set_bit(MPTCP_DATA_READY, &msk->flags);
sk->sk_data_ready(sk);
+ }
}
static bool mptcp_do_flush_join_list(struct mptcp_sock *msk)
@@ -374,7 +374,6 @@ mptcp_subflow_rsk(const struct request_sock *rsk)
enum mptcp_data_avail {
MPTCP_SUBFLOW_NODATA,
MPTCP_SUBFLOW_DATA_AVAIL,
- MPTCP_SUBFLOW_OOO_DATA
};
struct mptcp_delegated_action {
@@ -1137,18 +1137,13 @@ static bool subflow_check_data_avail(struct sock *ssk)
ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack,
ack_seq);
- if (ack_seq == old_ack) {
- subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
- break;
- } else if (after64(ack_seq, old_ack)) {
- subflow->data_avail = MPTCP_SUBFLOW_OOO_DATA;
- break;
+ if (unlikely(before64(ack_seq, old_ack))) {
+ mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
+ continue;
}
- /* only accept in-sequence mapping. Old values are spurious
- * retransmission
- */
- mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
+ subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL;
+ break;
}
return true;
Currently we relay on the subflow->data_avail field, which is subject to races: ssk1 skb len = 500 DSS(seq=1, len=1000, off=0) # data_avail == MPTCP_SUBFLOW_DATA_AVAIL ssk2 skb len = 500 DSS(seq = 501, len=1000) # data_avail == MPTCP_SUBFLOW_DATA_AVAIL ssk1 skb len = 500 DSS(seq = 1, len=1000, off =500) # still data_avail == MPTCP_SUBFLOW_DATA_AVAIL, # as the skb is covered by a pre-existing map, # which was in-sequence at reception time. Instead we can explicitly check if some has been received in-sequence, propagating the info from __mptcp_move_skbs_from_subflow(). Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/mptcp/protocol.c | 25 +++++++++---------------- net/mptcp/protocol.h | 1 - net/mptcp/subflow.c | 15 +++++---------- 3 files changed, 14 insertions(+), 27 deletions(-)