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(h-178-174-189-39.A498.priv.bahnhof.se. [178.174.189.39]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-30be9918c54sm20761671fa.62.2025.03.11.09.08.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Mar 2025 09:08:33 -0700 (PDT) From: Ulf Hansson To: "Rafael J . Wysocki" , linux-pm@vger.kernel.org Cc: Len Brown , Pavel Machek , Ulf Hansson , linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] PM: s2idle: Drop redundant locks when entering s2idle Date: Tue, 11 Mar 2025 17:08:22 +0100 Message-ID: <20250311160827.1129643-2-ulf.hansson@linaro.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250311160827.1129643-1-ulf.hansson@linaro.org> References: <20250311160827.1129643-1-ulf.hansson@linaro.org> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 --- Changes in v2: - Added a comment in the code. --- kernel/power/suspend.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 09f8397bae15..90fb06ca07d2 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -91,6 +91,8 @@ static void s2idle_enter(void) { trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true); + /* CPUs can't be hotplugged here so let's not protect for it. */ + raw_spin_lock_irq(&s2idle_lock); if (pm_wakeup_pending()) goto out; @@ -98,8 +100,6 @@ 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 +112,6 @@ static void s2idle_enter(void) */ wake_up_all_idle_cpus(); - cpus_read_unlock(); - raw_spin_lock_irq(&s2idle_lock); out: From patchwork Tue Mar 11 16:08:23 2025 Content-Type: text/plain; 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(h-178-174-189-39.A498.priv.bahnhof.se. [178.174.189.39]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-30be9918c54sm20761671fa.62.2025.03.11.09.08.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Mar 2025 09:08:34 -0700 (PDT) From: Ulf Hansson To: "Rafael J . Wysocki" , linux-pm@vger.kernel.org Cc: Len Brown , Pavel Machek , Ulf Hansson , linux-kernel@vger.kernel.org Subject: [PATCH v2 2/2] PM: s2idle: Extend comment in s2idle_enter() Date: Tue, 11 Mar 2025 17:08:23 +0100 Message-ID: <20250311160827.1129643-3-ulf.hansson@linaro.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250311160827.1129643-1-ulf.hansson@linaro.org> References: <20250311160827.1129643-1-ulf.hansson@linaro.org> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The s2idle_lock must be held while checking for a pending wakeup and while moving into S2IDLE_STATE_ENTER, to make sure a wakeup doesn't get lost. Let's extend the comment in the code to make this clear. Signed-off-by: Ulf Hansson --- Changes in v2: - New patch. Suggested by Rafael. --- kernel/power/suspend.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 90fb06ca07d2..b7aa1db278ff 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -91,8 +91,12 @@ static void s2idle_enter(void) { trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true); - /* CPUs can't be hotplugged here so let's not protect for it. */ - + /* + * The s2idle_lock must be held while checking for a pending wakeup and + * while moving into S2IDLE_STATE_ENTER, to make sure a wakeup doesn't + * get lost. Note also that CPUs can't be hotplugged here so let's not + * protect for it. + */ raw_spin_lock_irq(&s2idle_lock); if (pm_wakeup_pending()) goto out;