io_uring: clear TIF_NOTIFY_SIGNAL if set and task_work not available

With how task_work is added and signaled, we can have TIF_NOTIFY_SIGNAL
set and no task_work pending as it got run in a previous loop. Treat
TIF_NOTIFY_SIGNAL like get_signal(), always clear it if set regardless
of whether or not task_work is pending to run.

Cc: stable@vger.kernel.org
Fixes: 46a525e199e4 ("io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index cef5ff9..50bc3af 100644 (file)
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -238,9 +238,14 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
 
 static inline int io_run_task_work(void)
 {
+       /*
+        * Always check-and-clear the task_work notification signal. With how
+        * signaling works for task_work, we can find it set with nothing to
+        * run. We need to clear it for that case, like get_signal() does.
+        */
+       if (test_thread_flag(TIF_NOTIFY_SIGNAL))
+               clear_notify_signal();
        if (task_work_pending(current)) {
-               if (test_thread_flag(TIF_NOTIFY_SIGNAL))
-                       clear_notify_signal();
                __set_current_state(TASK_RUNNING);
                task_work_run();
                return 1;