tree 66de3253898e9fc1128e7c7e7ed326bfd378ff9b
parent ce593a6c480a22acba08795be313c0c6d49dd35d
author Jens Axboe <axboe@kernel.dk> 1593874550 -0600
committer Jens Axboe <axboe@kernel.dk> 1593891885 -0600

io_uring: fix regression with always ignoring signals in io_cqring_wait()

When switching to TWA_SIGNAL for task_work notifications, we also made
any signal based condition in io_cqring_wait() return -ERESTARTSYS.
This breaks applications that rely on using signals to abort someone
waiting for events.

Check if we have a signal pending because of queued task_work, and
repeat the signal check once we've run the task_work. This provides a
reliable way of telling the two apart.

Additionally, only use TWA_SIGNAL if we are using an eventfd. If not,
we don't have the dependency situation described in the original commit,
and we can get by with just using TWA_RESUME like we previously did.

Fixes: ce593a6c480a ("io_uring: use signal based task_work running")
Cc: stable@vger.kernel.org # v5.7
Reported-by: Andres Freund <andres@anarazel.de>
Tested-by: Andres Freund <andres@anarazel.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>