linux-kernel - [PATCH] perf: Fix the POLL

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Message-Id: <20250811182644.1305952-1-kan.liang@linux.intel.com>
Date: Mon, 11 Aug 2025 11:26:44 -0700
From: kan.liang@...ux.intel.com
To: peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	linux-s390@...r.kernel.org
Cc: Kan Liang <kan.liang@...ux.intel.com>,
	Sumanth Korikkar <sumanthk@...ux.ibm.com>
Subject: [PATCH] perf: Fix the POLL_HUP delivery breakage

From: Kan Liang <kan.liang@...ux.intel.com>

The event_limit can be set by the PERF_EVENT_IOC_REFRESH to limit the
number of events. When the event_limit reaches 0, the POLL_HUP signal
should be sent. But it's missed.

The corresponding counter should be stopped when the event_limit reaches
0. It was implemented in the ARCH-specific code. However, since the
commit 9734e25fbf5a ("perf: Fix the throttle logic for a group"), all
the ARCH-specific code has been moved to the generic code. The code to
handle the event_limit was lost.

Add the event->pmu->stop(event, 0); back.

Fixes: 9734e25fbf5a ("perf: Fix the throttle logic for a group")
Closes: https://lore.kernel.org/lkml/aICYAqM5EQUlTqtX@li-2b55cdcc-350b-11b2-a85c-a78bff51fc11.ibm.com/
Reported-by: Sumanth Korikkar <sumanthk@...ux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@...ux.ibm.com>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 kernel/events/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index dd8cf3c7fb7a..ec19c456b66d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10378,6 +10378,7 @@ static int __perf_event_overflow(struct perf_event *event,
 		ret = 1;
 		event->pending_kill = POLL_HUP;
 		perf_event_disable_inatomic(event);
+		event->pmu->stop(event, 0);
 	}
 
 	if (event->attr.sigtrap) {
-- 
2.38.1