linux-kernel - [PATCH v3 13/15] perf: Use scoped_guard() for mmap_mutex in perf

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Message-ID: <20250812104019.838047976@infradead.org>
Date: Tue, 12 Aug 2025 12:39:11 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: tglx@...utronix.de
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org,
 torvalds@...uxfoundation.org,
 mingo@...nel.org,
 namhyung@...nel.org,
 acme@...hat.com,
 kees@...nel.org
Subject: [PATCH v3 13/15] perf: Use scoped_guard() for mmap_mutex in perf_mmap()

Mostly just re-indent noise.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/events/core.c |   32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7143,27 +7143,23 @@ static int perf_mmap(struct file *file,
 	if (vma_size != PAGE_SIZE * nr_pages)
 		return -EINVAL;
 
-	mutex_lock(&event->mmap_mutex);
-	ret = -EINVAL;
+	scoped_guard (mutex, &event->mmap_mutex) {
+		/*
+		 * This relies on __pmu_detach_event() taking mmap_mutex after marking
+		 * the event REVOKED. Either we observe the state, or __pmu_detach_event()
+		 * will detach the rb created here.
+		 */
+		if (event->state <= PERF_EVENT_STATE_REVOKED) {
+			ret = -ENODEV;
+			break;
+		}
 
-	/*
-	 * This relies on __pmu_detach_event() taking mmap_mutex after marking
-	 * the event REVOKED. Either we observe the state, or __pmu_detach_event()
-	 * will detach the rb created here.
-	 */
-	if (event->state <= PERF_EVENT_STATE_REVOKED) {
-		ret = -ENODEV;
-		goto unlock;
+		if (vma->vm_pgoff == 0)
+			ret = perf_mmap_rb(vma, event, nr_pages);
+		else
+			ret = perf_mmap_aux(vma, event, nr_pages);
 	}
 
-	if (vma->vm_pgoff == 0)
-		ret = perf_mmap_rb(vma, event, nr_pages);
-	else
-		ret = perf_mmap_aux(vma, event, nr_pages);
-
-unlock:
-	mutex_unlock(&event->mmap_mutex);
-
 	if (ret)
 		return ret;