| Message ID | 1538579279-11614-1-git-send-email-laoar.shao@gmail.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net-next] inet: do not set backlog if listen fails | expand |
On 10/03/2018 08:07 AM, Yafang Shao wrote: > These two backlog members are not necessary set in inet_csk_listen_start(). > Regarding sk_max_ack_backlog, it will be set in the caller inet_listen > and dccp_listen_start. > Regraing sk_ack_backlog, it is better to put it together with > sk_max_ack_backlog in the same function and only set on success. > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > net/dccp/proto.c | 1 + > net/ipv4/af_inet.c | 1 + > net/ipv4/inet_connection_sock.c | 3 --- > 3 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/dccp/proto.c b/net/dccp/proto.c > index 875858c..34d48cd 100644 > --- a/net/dccp/proto.c > +++ b/net/dccp/proto.c > @@ -959,6 +959,7 @@ int inet_dccp_listen(struct socket *sock, int backlog) > err = dccp_listen_start(sk, backlog); > if (err) > goto out; > + sk->sk_ack_backlog = 0; This is racy, remember that dccp and tcp have lockless listeners. Do not change sk_ack_backlog after a TCP/DCCP socket is ready to accept new flows.
On Wed, Oct 3, 2018 at 11:41 PM Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > > On 10/03/2018 08:07 AM, Yafang Shao wrote: > > These two backlog members are not necessary set in inet_csk_listen_start(). > > Regarding sk_max_ack_backlog, it will be set in the caller inet_listen > > and dccp_listen_start. > > Regraing sk_ack_backlog, it is better to put it together with > > sk_max_ack_backlog in the same function and only set on success. > > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > --- > > net/dccp/proto.c | 1 + > > net/ipv4/af_inet.c | 1 + > > net/ipv4/inet_connection_sock.c | 3 --- > > 3 files changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/net/dccp/proto.c b/net/dccp/proto.c > > index 875858c..34d48cd 100644 > > --- a/net/dccp/proto.c > > +++ b/net/dccp/proto.c > > @@ -959,6 +959,7 @@ int inet_dccp_listen(struct socket *sock, int backlog) > > err = dccp_listen_start(sk, backlog); > > if (err) > > goto out; > > + sk->sk_ack_backlog = 0; > > > This is racy, remember that dccp and tcp have lockless listeners. > > Do not change sk_ack_backlog after a TCP/DCCP socket is ready to accept new flows. Understood. Thanks for your explanation.
diff --git a/net/dccp/proto.c b/net/dccp/proto.c index 875858c..34d48cd 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -959,6 +959,7 @@ int inet_dccp_listen(struct socket *sock, int backlog) err = dccp_listen_start(sk, backlog); if (err) goto out; + sk->sk_ack_backlog = 0; } sk->sk_max_ack_backlog = backlog; err = 0; diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 1fbe2f8..9690e0d 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -230,6 +230,7 @@ int inet_listen(struct socket *sock, int backlog) if (err) goto out; tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_LISTEN_CB, 0, NULL); + sk->sk_ack_backlog = 0; } sk->sk_max_ack_backlog = backlog; err = 0; diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index dfd5009..c25d0b3 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -870,9 +870,6 @@ int inet_csk_listen_start(struct sock *sk, int backlog) int err = -EADDRINUSE; reqsk_queue_alloc(&icsk->icsk_accept_queue); - - sk->sk_max_ack_backlog = backlog; - sk->sk_ack_backlog = 0; inet_csk_delack_init(sk); /* There is race window here: we announce ourselves listening,
These two backlog members are not necessary set in inet_csk_listen_start(). Regarding sk_max_ack_backlog, it will be set in the caller inet_listen and dccp_listen_start. Regraing sk_ack_backlog, it is better to put it together with sk_max_ack_backlog in the same function and only set on success. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- net/dccp/proto.c | 1 + net/ipv4/af_inet.c | 1 + net/ipv4/inet_connection_sock.c | 3 --- 3 files changed, 2 insertions(+), 3 deletions(-)