linux-kernel - [PATCH v2 2/8] x86/itmt: Use guard() for itmt_update

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Message-ID: <20241223043407.1611-3-kprateek.nayak@amd.com>
Date: Mon, 23 Dec 2024 04:34:01 +0000
From: K Prateek Nayak <kprateek.nayak@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: "H. Peter Anvin" <hpa@...or.com>, Dietmar Eggemann
	<dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, Ben Segall
	<bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, Valentin Schneider
	<vschneid@...hat.com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>, Tim Chen
	<tim.c.chen@...ux.intel.com>, Shrikanth Hegde <sshegde@...ux.ibm.com>, "Mario
 Limonciello" <mario.limonciello@....com>, Meng Li <li.meng@....com>, Huang
 Rui <ray.huang@....com>, "Gautham R. Shenoy" <gautham.shenoy@....com>, "K
 Prateek Nayak" <kprateek.nayak@....com>
Subject: [PATCH v2 2/8] x86/itmt: Use guard() for itmt_update_mutex

Use guard() for itmt_update_mutex which avoids the extra mutex_unlock()
in the bailout and return paths.

Reviewed-by: Tim Chen <tim.c.chen@...ux.intel.com>
Signed-off-by: K Prateek Nayak <kprateek.nayak@....com>
---
v1..v2:

o Collected tags from Tim.
---
 arch/x86/kernel/itmt.c | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c
index 28f449123d68..ee43d1bd41d0 100644
--- a/arch/x86/kernel/itmt.c
+++ b/arch/x86/kernel/itmt.c
@@ -44,12 +44,10 @@ static int sched_itmt_update_handler(const struct ctl_table *table, int write,
 	unsigned int old_sysctl;
 	int ret;
 
-	mutex_lock(&itmt_update_mutex);
+	guard(mutex)(&itmt_update_mutex);
 
-	if (!sched_itmt_capable) {
-		mutex_unlock(&itmt_update_mutex);
+	if (!sched_itmt_capable)
 		return -EINVAL;
-	}
 
 	old_sysctl = sysctl_sched_itmt_enabled;
 	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
@@ -59,8 +57,6 @@ static int sched_itmt_update_handler(const struct ctl_table *table, int write,
 		rebuild_sched_domains();
 	}
 
-	mutex_unlock(&itmt_update_mutex);
-
 	return ret;
 }
 
@@ -97,18 +93,14 @@ static struct ctl_table_header *itmt_sysctl_header;
  */
 int sched_set_itmt_support(void)
 {
-	mutex_lock(&itmt_update_mutex);
+	guard(mutex)(&itmt_update_mutex);
 
-	if (sched_itmt_capable) {
-		mutex_unlock(&itmt_update_mutex);
+	if (sched_itmt_capable)
 		return 0;
-	}
 
 	itmt_sysctl_header = register_sysctl("kernel", itmt_kern_table);
-	if (!itmt_sysctl_header) {
-		mutex_unlock(&itmt_update_mutex);
+	if (!itmt_sysctl_header)
 		return -ENOMEM;
-	}
 
 	sched_itmt_capable = true;
 
@@ -117,8 +109,6 @@ int sched_set_itmt_support(void)
 	x86_topology_update = true;
 	rebuild_sched_domains();
 
-	mutex_unlock(&itmt_update_mutex);
-
 	return 0;
 }
 
@@ -134,12 +124,11 @@ int sched_set_itmt_support(void)
  */
 void sched_clear_itmt_support(void)
 {
-	mutex_lock(&itmt_update_mutex);
+	guard(mutex)(&itmt_update_mutex);
 
-	if (!sched_itmt_capable) {
-		mutex_unlock(&itmt_update_mutex);
+	if (!sched_itmt_capable)
 		return;
-	}
+
 	sched_itmt_capable = false;
 
 	if (itmt_sysctl_header) {
@@ -153,8 +142,6 @@ void sched_clear_itmt_support(void)
 		x86_topology_update = true;
 		rebuild_sched_domains();
 	}
-
-	mutex_unlock(&itmt_update_mutex);
 }
 
 int arch_asym_cpu_priority(int cpu)
-- 
2.43.0