linux-kernel - [PATCH v2 4/4] smp: Defer check for local execution in smp_call_function_many

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Message-ID: <20250623000010.10124-5-yury.norov@gmail.com>
Date: Sun, 22 Jun 2025 20:00:09 -0400
From: Yury Norov <yury.norov@...il.com>
To: "Paul E. McKenney" <paulmck@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	"Yury Norov [NVIDIA]" <yury.norov@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Thorsten Blum <thorsten.blum@...ux.dev>,
	Zqiang <qiang.zhang1211@...il.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/4] smp: Defer check for local execution in smp_call_function_many_cond()

From: "Yury Norov [NVIDIA]" <yury.norov@...il.com>

Defer check for local execution to the actual place where it is needed,
and save some stack on a useless local variable.

Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
---
 kernel/smp.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 715190669e94..84561258cd22 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -779,7 +779,6 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	bool wait = scf_flags & SCF_WAIT;
 	int nr_cpus = 0;
 	bool run_remote = false;
-	bool run_local = false;
 
 	lockdep_assert_preemption_disabled();
 
@@ -801,11 +800,6 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	 */
 	WARN_ON_ONCE(!in_task());
 
-	/* Check if we need local execution. */
-	if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask) &&
-	    (!cond_func || cond_func(this_cpu, info)))
-		run_local = true;
-
 	/* Check if we need remote execution, i.e., any CPU excluding this one. */
 	if (cpumask_any_and_but(mask, cpu_online_mask, this_cpu) < nr_cpu_ids) {
 		run_remote = true;
@@ -853,7 +847,9 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 			run_remote = false;
 	}
 
-	if (run_local) {
+	/* Check if we need local execution. */
+	if ((scf_flags & SCF_RUN_LOCAL) && cpumask_test_cpu(this_cpu, mask) &&
+	    (!cond_func || cond_func(this_cpu, info))) {
 		unsigned long flags;
 
 		local_irq_save(flags);
-- 
2.43.0