linux-kernel - [PATCH] perf/x86: Use guard(mutex) instead of mutex

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Message-Id: <20250829114816.650576-1-liaoyuanhong@vivo.com>
Date: Fri, 29 Aug 2025 19:48:16 +0800
From: Liao Yuanhong <liaoyuanhong@...o.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
	"H. Peter Anvin" <hpa@...or.com>,
	linux-perf-users@...r.kernel.org (open list:PERFORMANCE EVENTS SUBSYSTEM),
	linux-kernel@...r.kernel.org (open list:PERFORMANCE EVENTS SUBSYSTEM)
Cc: Liao Yuanhong <liaoyuanhong@...o.com>
Subject: [PATCH] perf/x86: Use guard(mutex) instead of mutex_lock() to simplify code

Using guard(mutex) and scoped_guard() instead of mutex_lock/mutex_unlock
pair. Simplifies the error handling to just return in case of error. No
need for the fail_unlock: label anymore so remove it.

Signed-off-by: Liao Yuanhong <liaoyuanhong@...o.com>
---
 arch/x86/events/core.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 745caa6c15a3..107bed5c9d71 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -411,7 +411,7 @@ int x86_reserve_hardware(void)
 	int err = 0;
 
 	if (!atomic_inc_not_zero(&pmc_refcount)) {
-		mutex_lock(&pmc_reserve_mutex);
+		guard(mutex)(&pmc_reserve_mutex);
 		if (atomic_read(&pmc_refcount) == 0) {
 			if (!reserve_pmc_hardware()) {
 				err = -EBUSY;
@@ -422,7 +422,6 @@ int x86_reserve_hardware(void)
 		}
 		if (!err)
 			atomic_inc(&pmc_refcount);
-		mutex_unlock(&pmc_reserve_mutex);
 	}
 
 	return err;
@@ -444,8 +443,6 @@ void x86_release_hardware(void)
  */
 int x86_add_exclusive(unsigned int what)
 {
-	int i;
-
 	/*
 	 * When lbr_pt_coexist we allow PT to coexist with either LBR or BTS.
 	 * LBR and BTS are still mutually exclusive.
@@ -454,22 +451,18 @@ int x86_add_exclusive(unsigned int what)
 		goto out;
 
 	if (!atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what])) {
-		mutex_lock(&pmc_reserve_mutex);
-		for (i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++) {
-			if (i != what && atomic_read(&x86_pmu.lbr_exclusive[i]))
-				goto fail_unlock;
+		scoped_guard(mutex, &pmc_reserve_mutex) {
+			for (int i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++) {
+				if (i != what && atomic_read(&x86_pmu.lbr_exclusive[i]))
+					return -EBUSY;
+			}
+			atomic_inc(&x86_pmu.lbr_exclusive[what]);
 		}
-		atomic_inc(&x86_pmu.lbr_exclusive[what]);
-		mutex_unlock(&pmc_reserve_mutex);
 	}
 
 out:
 	atomic_inc(&active_events);
 	return 0;
-
-fail_unlock:
-	mutex_unlock(&pmc_reserve_mutex);
-	return -EBUSY;
 }
 
 void x86_del_exclusive(unsigned int what)
-- 
2.34.1