5.4-stable review patch. If anyone has any objections, please let me know.
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From: Tao Chen chen.dylane@linux.dev
[ Upstream commit c96fff391c095c11dc87dab35be72dee7d217cde ]
The poll man page says POLLRDNORM is equivalent to POLLIN. For poll(), it seems that if user sets pollfd with POLLRDNORM in userspace, perf_poll will not return until timeout even if perf_output_wakeup called, whereas POLLIN returns.
Fixes: 76369139ceb9 ("perf: Split up buffer handling from core code") Signed-off-by: Tao Chen chen.dylane@linux.dev Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Arnaldo Carvalho de Melo acme@redhat.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/20250314030036.2543180-1-chen.dylane@linux.dev Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 679cc87b40f4b..0611477e4dadd 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -19,7 +19,7 @@
static void perf_output_wakeup(struct perf_output_handle *handle) { - atomic_set(&handle->rb->poll, EPOLLIN); + atomic_set(&handle->rb->poll, EPOLLIN | EPOLLRDNORM);
handle->event->pending_wakeup = 1; irq_work_queue(&handle->event->pending);