The wakeup condition if a min timeout is present and has expired is that at least _one_ CQE was posted. Thus set the cq_tail target to ->cq_min_tail + 1. Without this commit a spurious wakeup can result in a premature wakeup because io_should_wake() will return true even if _no_ CQE was posted at all. Tested by running the liburing testsuite with no regressions. Additionally, tested by turning all calls to schedule() in io_uring/wait.c into calls to schedule_timeout(1) to force the spurious wakeups. With these spurious wakeups the min-timeout.t test fails before and passes after this commit. Cc: Jens Axboe Cc: Tip ten Brink Fixes: e15cb2200b93 ("io_uring: fix min_wait wakeups for SQPOLL") Cc: stable@vger.kernel.org Signed-off-by: Christian A. Ehrhardt --- io_uring/wait.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/io_uring/wait.c b/io_uring/wait.c index ec01e78a216d..d005ea17b35f 100644 --- a/io_uring/wait.c +++ b/io_uring/wait.c @@ -103,7 +103,7 @@ static enum hrtimer_restart io_cqring_min_timer_wakeup(struct hrtimer *timer) } /* any generated CQE posted past this time should wake us up */ - iowq->cq_tail = iowq->cq_min_tail; + iowq->cq_tail = iowq->cq_min_tail + 1; hrtimer_update_function(&iowq->t, io_cqring_timer_wakeup); hrtimer_set_expires(timer, iowq->timeout); -- 2.43.0