io_uring: fix ->flags races by linked timeouts

[ Upstream commit efe814a471e0e58f28f1efaf430c8784a4f36626 ]

It's racy to modify req->flags from a not owning context, e.g. linked
timeout calling req_set_fail_links() for the master request might race
with that request setting/clearing flags while being executed
concurrently. Just remove req_set_fail_links(prev) from
io_link_timeout_fn(), io_async_find_and_cancel() and functions down the
line take care of setting the fail bit.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index dde290eb7dd0c84a39a7d8f9a0f713446fecb459..4e53445db73ff101ac7287f6f0d6dde1a3dacb2b 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6242,7 +6242,6 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
        spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
        if (prev) {
-               req_set_fail_links(prev);
                io_async_find_and_cancel(ctx, req, prev->user_data, -ETIME);
                io_put_req_deferred(prev, 1);
        } else {