From: Petr Malat <oss@malat.biz>
Date: Fri, 16 May 2025 08:17:28 +0000 (+0200)
Subject: sctp: Do not wake readers in __sctp_write_space()
X-Git-Tag: v6.16-rc1~132^2~73
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af295892a7abbf05a3c2ba7abc4d81bb448623d6;p=thirdparty%2Fkernel%2Flinux.git

sctp: Do not wake readers in __sctp_write_space()

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@malat.biz>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20250516081727.1361451-1-oss@malat.biz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 85a9dfeff4d6a..90b75d4ec3298 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.