Adding io_uring support to Netty, Josef noticed that there's another
case where we can fail to process task_work in time. We previously
added a "work-around" for eventfd, see:
b7db41c9e03b ("io_uring: fix regression with always ignoring signals in io_cqring_wait()")
but we can run into this dependency issue even without that. See the
test case added to liburing:
https://git.kernel.dk/cgit/liburing/tree/test/wakeup-hang.c
for an example of that. This series adds a split way to call
task_work_add(), so we can use TWA_SIGNAL if the task is currently
not running. This over-reaches a bit since there are definitely cases
where we do not need to use it, but better safe than sorry for now.
--
Jens Axboe
