[PATCH AUTOSEL 5.10 23/39] io_uring: fix ->flags races by linked timeouts

Sasha Levin
2021-03-25T11:31:24Z

From: Pavel Begunkov <asml.silence@gmail.com>

[ 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>
---
fs/io_uring.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 691c99869143..8f57fd328df6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6231,7 +6231,6 @@ 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(prev);
} else {
--
2.30.1