[PATCH linux-next v2] perf/ring_buffer: Add EPOLLRDNORM flag for poll

From: Tao Chen
Date: Thu Mar 13 2025 - 23:01:22 EST


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@xxxxxxxxx>
---
kernel/events/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Change list:
- v1 -> v2:
- add changelog
- v1
https://lore.kernel.org/all/20250313051047.2436098-1-chen.dylane@xxxxxxxxx

diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 59a52b1a1..5130b119d 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;

--
2.43.0