linux-kernel - [tip: irq/core] cpuidle: Avoid explicit cpumask allocation on stack

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Message-ID: <171398904609.10875.5352483996158026300.tip-bot2@tip-bot2>
Date: Wed, 24 Apr 2024 20:04:06 -0000
From: "tip-bot2 for Dawei Li" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Dawei Li <dawei.li@...ngroup.cn>, Thomas Gleixner <tglx@...utronix.de>,
 x86@...nel.org, linux-kernel@...r.kernel.org, maz@...nel.org
Subject: [tip: irq/core] cpuidle: Avoid explicit cpumask allocation on stack

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     6f28c4a852fab8bd759a383149dfd30511477249
Gitweb:        https://git.kernel.org/tip/6f28c4a852fab8bd759a383149dfd30511477249
Author:        Dawei Li <dawei.li@...ngroup.cn>
AuthorDate:    Tue, 16 Apr 2024 16:54:54 +08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 24 Apr 2024 21:23:49 +02:00

cpuidle: Avoid explicit cpumask allocation on stack

In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_first_and_and() and cpumask_weight_and() to avoid the need
for a temporary cpumask on the stack.

Signed-off-by: Dawei Li <dawei.li@...ngroup.cn>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20240416085454.3547175-8-dawei.li@shingroup.cn

---
 drivers/cpuidle/coupled.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
index 9acde71..bb8761c 100644
--- a/drivers/cpuidle/coupled.c
+++ b/drivers/cpuidle/coupled.c
@@ -439,13 +439,8 @@ static int cpuidle_coupled_clear_pokes(int cpu)
 
 static bool cpuidle_coupled_any_pokes_pending(struct cpuidle_coupled *coupled)
 {
-	cpumask_t cpus;
-	int ret;
-
-	cpumask_and(&cpus, cpu_online_mask, &coupled->coupled_cpus);
-	ret = cpumask_and(&cpus, &cpuidle_coupled_poke_pending, &cpus);
-
-	return ret;
+	return cpumask_first_and_and(cpu_online_mask, &coupled->coupled_cpus,
+				     &cpuidle_coupled_poke_pending) < nr_cpu_ids;
 }
 
 /**
@@ -626,9 +621,7 @@ out:
 
 static void cpuidle_coupled_update_online_cpus(struct cpuidle_coupled *coupled)
 {
-	cpumask_t cpus;
-	cpumask_and(&cpus, cpu_online_mask, &coupled->coupled_cpus);
-	coupled->online_count = cpumask_weight(&cpus);
+	coupled->online_count = cpumask_weight_and(cpu_online_mask, &coupled->coupled_cpus);
 }
 
 /**