linux-kernel - [PATCH v2 -next 2/2] PM: suspend: advanced pm_wakeup

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Date:   Thu, 30 Jun 2022 08:57:18 +0800
From:   xiongxin <xiongxin@...inos.cn>
To:     rafael@...nel.org, len.brown@...el.com, pavel@....cz,
        xiongxin@...inos.cn, luriwen@...inos.cn
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 -next 2/2] PM: suspend: advanced pm_wakeup_clear() for normal suspend/hibernate

pm_wakeup_clear() will clear the wakeup source, which can ensure that it
is not disturbed by useless wakeup signals when doing suspend/hibernate;

At the beginning of the suspend/hibernate process, the notifier
mechanism is used to notify other device drivers. This action is
time-consuming (second-level time-consuming). If the process fails due
to the received wakeup signal during the execution of these functions,
it can better improve the experience of failing suspend/hibernate
returns;

Therefore, it is recommended here that for the suspend/hibernate process
normally called from /sys/power/state, the pm_wakeup_clear() function
should be brought before the notifier call; for the freeze_process()
function called from other places, the original logic is kept;

The pm_suspend_target_state variable is used here to identify whether the
suspend process is going normally.

Signed-off-by: xiongxin <xiongxin@...inos.cn>
---
 kernel/power/process.c | 5 ++++-
 kernel/power/suspend.c | 6 ++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 3068601e585a..3fde0240b3d1 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -131,7 +131,10 @@ int freeze_processes(void)
 	if (!pm_freezing)
 		atomic_inc(&system_freezing_cnt);
 
-	pm_wakeup_clear(0);
+	if (pm_suspend_target_state != PM_SUSPEND_ON)
+		pm_wakeup_clear(1);
+	else
+		pm_wakeup_clear(0);
 	pr_info("Freezing user space processes ... ");
 	pm_freezing = true;
 	error = try_to_freeze_tasks(true);
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 4cfa464600bf..2a82db57adc9 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -569,6 +569,12 @@ static int enter_state(suspend_state_t state)
 	 * performed from the /sys/power/state entry.
 	 */
 	pm_suspend_target_state = state;
+	/*
+	 * Put pm_wakeup_clear() before the notifier notification chain to
+	 * optimize in the suspend process, the wakeup signal can interrupt
+	 * the suspend in advance and fail to return.
+	 */
+	pm_wakeup_clear(0);
 
 	if (sync_on_suspend_enabled) {
 		trace_suspend_resume(TPS("sync_filesystems"), 0, true);
-- 
2.25.1


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