From: Ulf Hansson Date: Tue, 11 Mar 2025 16:08:22 +0000 (+0100) Subject: PM: s2idle: Drop redundant locks when entering s2idle X-Git-Tag: v6.15-rc1~191^2~1^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0f42194c6b22d687fd53c8aea5413cf976366672;p=thirdparty%2Fkernel%2Flinux.git PM: s2idle: Drop redundant locks when entering s2idle The calls to cpus_read_lock|unlock() protects us from getting CPUS hotplugged, while entering suspend-to-idle. However, when s2idle_enter() is called we should be far beyond the point when CPUs may be hotplugged. Let's therefore simplify the code and drop the use of the lock. Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20250311160827.1129643-2-ulf.hansson@linaro.org [ rjw: Rewrote the new comment ] Signed-off-by: Rafael J. Wysocki --- diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 09f8397bae15f..1876abf1be15b 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -91,6 +91,12 @@ static void s2idle_enter(void) { trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true); + /* + * The correctness of the code below depends on the number of online + * CPUs being stable, but CPUs cannot be taken offline or put online + * while it is running. + */ + raw_spin_lock_irq(&s2idle_lock); if (pm_wakeup_pending()) goto out; @@ -98,8 +104,6 @@ static void s2idle_enter(void) s2idle_state = S2IDLE_STATE_ENTER; raw_spin_unlock_irq(&s2idle_lock); - cpus_read_lock(); - /* Push all the CPUs into the idle loop. */ wake_up_all_idle_cpus(); /* Make the current CPU wait so it can enter the idle loop too. */ @@ -112,8 +116,6 @@ static void s2idle_enter(void) */ wake_up_all_idle_cpus(); - cpus_read_unlock(); - raw_spin_lock_irq(&s2idle_lock); out: