On Mon, May 12, 2025 at 8:33 AM Petr Malat <oss@xxxxxxxxx> wrote:
>
> Function __sctp_write_space() doesn't set poll key, which leads to
> ep_poll_callback() waking up all waiters, not only these waiting
> for the socket being writable. Set the key properly using
> wake_up_interruptible_poll(), which is preferred over the sync
> variant, as writers are not woken up before at least half of the
> queue is available. Also, TCP does the same.
>
> Signed-off-by: Petr Malat <oss@xxxxxxxxx>
> ---
> net/sctp/socket.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 53725ee7ba06..b301d64d9d80 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -9100,7 +9100,8 @@ static void __sctp_write_space(struct sctp_association *asoc)
> wq = rcu_dereference(sk->sk_wq);
> if (wq) {
> if (waitqueue_active(&wq->wait))
> - wake_up_interruptible(&wq->wait);
> + wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
> + EPOLLWRNORM | EPOLLWRBAND);
>
> /* Note that we try to include the Async I/O support
> * here by modeling from the current TCP/UDP code.
> --
> 2.39.5
>
Acked-by: Xin Long <lucien.xin@xxxxxxxxx>
