Message ID | 1538919405-3093-1-git-send-email-laoar.shao@gmail.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
Series | [v2,net-next] inet: do not set backlog if listen fails | expand |
On 10/07/2018 06:36 AM, Yafang Shao wrote: > We don't need to set the backlog if listen fails. > The sk_max_ack_backlog will be set in the caller inet_listen() and > dccp_listen_start() if inet_csk_listen_start() return without error. > So just remove this line to avoid this unnecessary operation. > > Regarding sk_ack_backlog, we have to set it before a TCP/DCCP socket is > ready to accept new flows to avoid race, because dccp and tcp have lockless > listeners > Really could you not add irrelevant stuff in the changelog ? This patch simply removes one redundant setting, you do not have to explain about dccp/tcp being lockless and that sk_ack_backlog is not touched by this patch. Also the title is misleading, since we will still set the backlog even if the listen fails. If you really want sk_max_ack_backlog being not changed if listen() fails, then I am afraid you will need to submit a different patch.
On Mon, Oct 8, 2018 at 1:39 AM Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > > On 10/07/2018 06:36 AM, Yafang Shao wrote: > > We don't need to set the backlog if listen fails. > > The sk_max_ack_backlog will be set in the caller inet_listen() and > > dccp_listen_start() if inet_csk_listen_start() return without error. > > So just remove this line to avoid this unnecessary operation. > > > > Regarding sk_ack_backlog, we have to set it before a TCP/DCCP socket is > > ready to accept new flows to avoid race, because dccp and tcp have lockless > > listeners > > > > Really could you not add irrelevant stuff in the changelog ? > Sure, I will remove it. > This patch simply removes one redundant setting, you do not have to explain > about dccp/tcp being lockless and that sk_ack_backlog is not touched by this patch. > > Also the title is misleading, since we will still set the backlog even if the listen > fails. > > If you really want sk_max_ack_backlog being not changed if listen() fails, > then I am afraid you will need to submit a different patch. After this patch, sk_max_ack_backlog will only be set after the sk is successfully added to listening hash table, and then 0 is returned, that means listen() is successful. Take inet_listen() for example, if (old_state != TCP_LISTEN) { err = inet_csk_listen_start(sk, backlog); if (err) goto out; } // it can only be set if err is 0. sk->sk_max_ack_backlog = backlog; err = 0; out: return err; Pls. correct me if I missed something. Thanks Yafang
On Mon, Oct 8, 2018 at 3:47 AM Yafang Shao <laoar.shao@gmail.com> wrote: > > > Pls. correct me if I missed something. > You missed that this variable must be set before listener is setup. Same feedback than prior version really (when you trived to move around sk_ack_backlog clearing) You are changing inet_csk_listen_start() but this is wrong...
On Mon, Oct 8, 2018 at 10:48 PM Eric Dumazet <edumazet@google.com> wrote: > > On Mon, Oct 8, 2018 at 3:47 AM Yafang Shao <laoar.shao@gmail.com> wrote: > > > > > > Pls. correct me if I missed something. > > > > You missed that this variable must be set before listener is setup. > Same feedback than prior version really (when you trived to move > around sk_ack_backlog clearing) > > You are changing inet_csk_listen_start() but this is wrong... Got it. Thank you.
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index dfd5009..cdd5c95 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -871,7 +871,6 @@ int inet_csk_listen_start(struct sock *sk, int backlog) reqsk_queue_alloc(&icsk->icsk_accept_queue); - sk->sk_max_ack_backlog = backlog; sk->sk_ack_backlog = 0; inet_csk_delack_init(sk);
We don't need to set the backlog if listen fails. The sk_max_ack_backlog will be set in the caller inet_listen() and dccp_listen_start() if inet_csk_listen_start() return without error. So just remove this line to avoid this unnecessary operation. Regarding sk_ack_backlog, we have to set it before a TCP/DCCP socket is ready to accept new flows to avoid race, because dccp and tcp have lockless listeners Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- net/ipv4/inet_connection_sock.c | 1 - 1 file changed, 1 deletion(-)