From: Pavel Begunkov asml.silence@gmail.com
commit b98186aee22fa593bc8c6b2c5d839c2ee518bc8c upstream.
When io_poll_check_events() collides with someone attempting to queue a task work, it'll spin for one more time. However, it'll continue to use the mask from the first iteration instead of updating it. For example, if the first wake up was a EPOLLIN and the second EPOLLOUT, the userspace will not get EPOLLOUT in time.
Clear the mask for all subsequent iterations to force vfs_poll().
Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/2dac97e8f691231049cb259c4ae57e79e40b537c.166871022... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/poll.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -256,6 +256,9 @@ static int io_poll_check_events(struct i return ret; }
+ /* force the next iteration to vfs_poll() */ + req->cqe.res = 0; + /* * Release all references, retry if someone tried to restart * task_work while we were executing it.