From: "Steven Rostedt (Google)" rostedt@goodmis.org
The wake up waiters only checks the "wakeup_full" variable and not the "full_waiters_pending". The full_waiters_pending is set when a waiter is added to the wait queue. The wakeup_full is only set when an event is triggered, and it clears the full_waiters_pending to avoid multiple calls to irq_work_queue().
The irq_work callback really needs to check both wakeup_full as well as full_waiters_pending such that this code can be used to wake up waiters when a file is closed that represents the ring buffer and the waiters need to be woken up.
Link: https://lkml.kernel.org/r/20220927231824.209460321@goodmis.org
Cc: stable@vger.kernel.org Cc: Ingo Molnar mingo@kernel.org Cc: Andrew Morton akpm@linux-foundation.org Fixes: 15693458c4bc0 ("tracing/ring-buffer: Move poll wake ups into ring buffer code") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/ring_buffer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 02db92c9eb1b..5a7d818ca3ea 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -917,8 +917,9 @@ static void rb_wake_up_waiters(struct irq_work *work) struct rb_irq_work *rbwork = container_of(work, struct rb_irq_work, work);
wake_up_all(&rbwork->waiters); - if (rbwork->wakeup_full) { + if (rbwork->full_waiters_pending || rbwork->wakeup_full) { rbwork->wakeup_full = false; + rbwork->full_waiters_pending = false; wake_up_all(&rbwork->full_waiters); } }