From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 13 Aug 2024 12:10:59 +0000 (-0600)
Subject: io_uring/sqpoll: annotate debug task == current with data_race()
X-Git-Tag: v6.11-rc4~18^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e4956dc7a84da074fd8dc10f7abd147f15b3ae58;p=thirdparty%2Fkernel%2Flinux.git

io_uring/sqpoll: annotate debug task == current with data_race()

There's a debug check in io_sq_thread_park() checking if it's the SQPOLL
thread itself calling park. KCSAN warns about this, as we should not be
reading sqd->thread outside of sqd->lock.

Just silence this with data_race(). The pointer isn't used for anything
but this debug check.

Reported-by: syzbot+2b946a3fd80caf971b21@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
index b3722e5275e77..3b50dc9586d14 100644
--- a/io_uring/sqpoll.c
+++ b/io_uring/sqpoll.c
@@ -44,7 +44,7 @@ void io_sq_thread_unpark(struct io_sq_data *sqd)
 void io_sq_thread_park(struct io_sq_data *sqd)
 	__acquires(&sqd->lock)
 {
-	WARN_ON_ONCE(sqd->thread == current);
+	WARN_ON_ONCE(data_race(sqd->thread) == current);
 
 	atomic_inc(&sqd->park_pending);
 	set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);