linux-kernel - [PATCH AUTOSEL 6.6 119/139] perf: Fix event_function

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Message-ID: <20240925121137.1307574-119-sashal@kernel.org>
Date: Wed, 25 Sep 2024 08:08:59 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	mingo@...hat.com,
	acme@...nel.org,
	linux-perf-users@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 119/139] perf: Fix event_function_call() locking

From: Peter Zijlstra <peterz@...radead.org>

[ Upstream commit 558abc7e3f895049faa46b08656be4c60dc6e9fd ]

All the event_function/@...c call context already uses perf_ctx_lock()
except for the !ctx->is_active case. Make it all consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Kan Liang <kan.liang@...ux.intel.com>
Reviewed-by: Namhyung Kim <namhyung@...nel.org>
Link: https://lore.kernel.org/r/20240807115550.138301094@infradead.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/events/core.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d40809bdf4b30..18eab7f50ecce 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -263,6 +263,7 @@ static int event_function(void *info)
 static void event_function_call(struct perf_event *event, event_f func, void *data)
 {
 	struct perf_event_context *ctx = event->ctx;
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
 	struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
 	struct event_function_struct efs = {
 		.event = event,
@@ -291,22 +292,22 @@ static void event_function_call(struct perf_event *event, event_f func, void *da
 	if (!task_function_call(task, event_function, &efs))
 		return;
 
-	raw_spin_lock_irq(&ctx->lock);
+	perf_ctx_lock(cpuctx, ctx);
 	/*
 	 * Reload the task pointer, it might have been changed by
 	 * a concurrent perf_event_context_sched_out().
 	 */
 	task = ctx->task;
 	if (task == TASK_TOMBSTONE) {
-		raw_spin_unlock_irq(&ctx->lock);
+		perf_ctx_unlock(cpuctx, ctx);
 		return;
 	}
 	if (ctx->is_active) {
-		raw_spin_unlock_irq(&ctx->lock);
+		perf_ctx_unlock(cpuctx, ctx);
 		goto again;
 	}
 	func(event, NULL, ctx, data);
-	raw_spin_unlock_irq(&ctx->lock);
+	perf_ctx_unlock(cpuctx, ctx);
 }
 
 /*
-- 
2.43.0