linux-kernel - [PATCH 1/2] io_uring: Fix race condition when sqp thread goes to sleep

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Message-Id: <67c806d0bcf2e096c1b0c7e87bd5926c37231b87.1624387080.git.olivier@trillion01.com>
Date:   Tue, 22 Jun 2021 11:45:20 -0700
From:   Olivier Langlois <olivier@...llion01.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        io-uring@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Olivier Langlois <olivier@...llion01.com>
Subject: [PATCH 1/2] io_uring: Fix race condition when sqp thread goes to
 sleep

If an asynchronous completion happens before the task is preparing
itself to wait and set its state to TASK_INTERRUPTABLE, the completion
will not wake up the sqp thread.

Signed-off-by: Olivier Langlois <olivier@...llion01.com>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index fc8637f591a6..02f789e07d4c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6902,7 +6902,7 @@ static int io_sq_thread(void *data)
 		}
 
 		prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
-		if (!io_sqd_events_pending(sqd)) {
+		if (!io_sqd_events_pending(sqd) && !current->task_works) {
 			needs_sched = true;
 			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
 				io_ring_set_wakeup_flag(ctx);
-- 
2.32.0