linux-kernel - [tip: perf/core] perf: Move irq_work_queue() where the event is prepared.

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Message-ID: <172052531946.2215.8696209749766596463.tip-bot2@tip-bot2>
Date: Tue, 09 Jul 2024 11:41:59 -0000
From: "tip-bot2 for Sebastian Andrzej Siewior" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Marco Elver <elver@...gle.com>, Arnaldo Carvalho de Melo <acme@...hat.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: perf/core] perf: Move irq_work_queue() where the event is prepared.

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     058244c683111d44a5de16ac74f19a1754dd7a0c
Gitweb:        https://git.kernel.org/tip/058244c683111d44a5de16ac74f19a1754dd7a0c
Author:        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate:    Thu, 04 Jul 2024 19:03:35 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 09 Jul 2024 13:26:34 +02:00

perf: Move irq_work_queue() where the event is prepared.

Only if perf_event::pending_sigtrap is zero, the irq_work accounted by
increminging perf_event::nr_pending. The member perf_event::pending_addr
might be overwritten by a subsequent event if the signal was not yet
delivered and is expected. The irq_work will not be enqeueued again
because it has a check to be only enqueued once.

Move irq_work_queue() to where the counter is incremented and
perf_event::pending_sigtrap is set to make it more obvious that the
irq_work is scheduled once.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Tested-by: Marco Elver <elver@...gle.com>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Link: https://lore.kernel.org/r/20240704170424.1466941-2-bigeasy@linutronix.de
---
 kernel/events/core.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 32c7996..c54da50 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9727,6 +9727,11 @@ static int __perf_event_overflow(struct perf_event *event,
 		if (!event->pending_sigtrap) {
 			event->pending_sigtrap = pending_id;
 			local_inc(&event->ctx->nr_pending);
+
+			event->pending_addr = 0;
+			if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
+				event->pending_addr = data->addr;
+			irq_work_queue(&event->pending_irq);
 		} else if (event->attr.exclude_kernel && valid_sample) {
 			/*
 			 * Should not be able to return to user space without
@@ -9742,11 +9747,6 @@ static int __perf_event_overflow(struct perf_event *event,
 			 */
 			WARN_ON_ONCE(event->pending_sigtrap != pending_id);
 		}
-
-		event->pending_addr = 0;
-		if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
-			event->pending_addr = data->addr;
-		irq_work_queue(&event->pending_irq);
 	}

 	READ_ONCE(event->overflow_handler)(event, data, regs);