PM: sleep: Rework cpuidle handling during system-wide PM transitions

From: Rafael J. Wysocki <[email protected]>

It is pointless to pause cpuidle in the suspend-to-idle path, because it is going to be resumed in the same path later and pausing it does not serve any particular purpose in that case.

Rework the code to avoid doing that.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/base/power/main.c |   11 ++++++-----
 kernel/power/suspend.c    |    8 ++++++--
 2 files changed, 12 insertions(+), 7 deletions(-)

Index: linux-pm/drivers/base/power/main.c
===================================================================

drivers/base/power/main.c +6 -5

@@ -747,8 +747,6 @@ void dpm_resume_noirq(pm_message_t state
 
        resume_device_irqs();
        device_wakeup_disarm_wake_irqs();
-
-       cpuidle_resume();
 }
 
 /**

@@ -881,6 +879,7 @@ void dpm_resume_early(pm_message_t state
 void dpm_resume_start(pm_message_t state)
 {
        dpm_resume_noirq(state);
+       cpuidle_resume();
        dpm_resume_early(state);
 }
 EXPORT_SYMBOL_GPL(dpm_resume_start);

@@ -1336,8 +1335,6 @@ int dpm_suspend_noirq(pm_message_t state
 {
        int ret;
 
-       cpuidle_pause();
-
        device_wakeup_arm_wake_irqs();
        suspend_device_irqs();
 

@@ -1521,9 +1518,13 @@ int dpm_suspend_end(pm_message_t state)
        if (error)
                goto out;
 
+       cpuidle_pause();
+
        error = dpm_suspend_noirq(state);
-       if (error)
+       if (error) {
+               cpuidle_resume();
                dpm_resume_early(resume_event(state));
+       }
 
 out:
        dpm_show_time(starttime, state, error, "end");

Index: linux-pm/kernel/power/suspend.c
===================================================================

kernel/power/suspend.c +6 -2

@@ -97,7 +97,6 @@ static void s2idle_enter(void)
        raw_spin_unlock_irq(&s2idle_lock);
 
        cpus_read_lock();
-       cpuidle_resume();
 
        /* Push all the CPUs into the idle loop. */
        wake_up_all_idle_cpus();

@@ -105,7 +104,6 @@ static void s2idle_enter(void)
        swait_event_exclusive(s2idle_wait_head,
                    s2idle_state == S2IDLE_STATE_WAKE);
 
-       cpuidle_pause();
        cpus_read_unlock();
 
        raw_spin_lock_irq(&s2idle_lock);

@@ -405,6 +403,9 @@ static int suspend_enter(suspend_state_t
        if (error)
                goto Devices_early_resume;
 
+       if (state != PM_SUSPEND_TO_IDLE)
+               cpuidle_pause();
+
        error = dpm_suspend_noirq(PMSG_SUSPEND);
        if (error) {
                pr_err("noirq suspend of devices failed\n");

@@ -459,6 +460,9 @@ static int suspend_enter(suspend_state_t
        dpm_resume_noirq(PMSG_RESUME);
 
  Platform_early_resume:
+       if (state != PM_SUSPEND_TO_IDLE)
+               cpuidle_resume();
+
        platform_resume_early(state);
 
  Devices_early_resume:

From: Rafael J. Wysocki <[email protected]>

Commit 8651f97bd951 ("PM / cpuidle: System resume hang fix with cpuidle") that introduced cpuidle pausing during system suspend did that to work around a platform firmware issue causing systems to hang during resume if CPUs were allowed to enter idle states in the system suspend and resume code paths.

However, pausing cpuidle before the last phase of suspending devices is the source of an otherwise arbitrary difference between the suspend-to-idle path and other system suspend variants, so it is cleaner to do that later, before taking secondary CPUs offline (it is still safer to take secondary CPUs offline with cpuidle paused, though).

Modify the code accordingly, but in order to avoid code duplication, introduce new wrapper functions, pm_sleep_disable_secondary_cpus() and pm_sleep_enable_secondary_cpus(), to combine cpuidle_pause() and cpuidle_resume(), respectively, with the handling of secondary CPUs during system-wide transitions to sleep states.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/base/power/main.c |    8 +-------
 kernel/power/hibernate.c  |   12 +++++++-----
 kernel/power/power.h      |   14 ++++++++++++++
 kernel/power/suspend.c    |   10 ++--------
 4 files changed, 24 insertions(+), 20 deletions(-)

Index: linux-pm/kernel/power/suspend.c
===================================================================

kernel/power/suspend.c +2 -8

@@ -403,9 +403,6 @@ static int suspend_enter(suspend_state_t
        if (error)
                goto Devices_early_resume;
 
-       if (state != PM_SUSPEND_TO_IDLE)
-               cpuidle_pause();
-
        error = dpm_suspend_noirq(PMSG_SUSPEND);
        if (error) {
                pr_err("noirq suspend of devices failed\n");

@@ -423,7 +420,7 @@ static int suspend_enter(suspend_state_t
                goto Platform_wake;
        }
 
-       error = suspend_disable_secondary_cpus();
+       error = pm_sleep_disable_secondary_cpus();
        if (error || suspend_test(TEST_CPUS))
                goto Enable_cpus;
 

@@ -453,16 +450,13 @@ static int suspend_enter(suspend_state_t
        BUG_ON(irqs_disabled());
 
  Enable_cpus:
-       suspend_enable_secondary_cpus();
+       pm_sleep_enable_secondary_cpus();
 
  Platform_wake:
        platform_resume_noirq(state);
        dpm_resume_noirq(PMSG_RESUME);
 
  Platform_early_resume:
-       if (state != PM_SUSPEND_TO_IDLE)
-               cpuidle_resume();
-
        platform_resume_early(state);
 
  Devices_early_resume:

Index: linux-pm/kernel/power/hibernate.c
===================================================================

kernel/power/hibernate.c +7 -5

@@ -300,7 +300,7 @@ static int create_image(int platform_mod
        if (error || hibernation_test(TEST_PLATFORM))
                goto Platform_finish;
 
-       error = suspend_disable_secondary_cpus();
+       error = pm_sleep_disable_secondary_cpus();
        if (error || hibernation_test(TEST_CPUS))
                goto Enable_cpus;
 

@@ -342,7 +342,7 @@ static int create_image(int platform_mod
        local_irq_enable();
 
  Enable_cpus:
-       suspend_enable_secondary_cpus();
+       pm_sleep_enable_secondary_cpus();
 
        /* Allow architectures to do nosmt-specific post-resume dances */
        if (!in_suspend)

@@ -466,6 +466,8 @@ static int resume_target_kernel(bool pla
        if (error)
                goto Cleanup;
 
+       cpuidle_pause();
+
        error = hibernate_resume_nonboot_cpu_disable();
        if (error)
                goto Enable_cpus;

@@ -509,7 +511,7 @@ static int resume_target_kernel(bool pla
        local_irq_enable();
 
  Enable_cpus:
-       suspend_enable_secondary_cpus();
+       pm_sleep_enable_secondary_cpus();
 
  Cleanup:
        platform_restore_cleanup(platform_mode);

@@ -587,7 +589,7 @@ int hibernation_platform_enter(void)
        if (error)
                goto Platform_finish;
 
-       error = suspend_disable_secondary_cpus();
+       error = pm_sleep_disable_secondary_cpus();
        if (error)
                goto Enable_cpus;
 

@@ -609,7 +611,7 @@ int hibernation_platform_enter(void)
        local_irq_enable();
 
  Enable_cpus:
-       suspend_enable_secondary_cpus();
+       pm_sleep_enable_secondary_cpus();
 
  Platform_finish:
        hibernation_ops->finish();

Index: linux-pm/drivers/base/power/main.c
===================================================================

drivers/base/power/main.c +1 -7

@@ -32,7 +32,6 @@
 #include <linux/suspend.h>
 #include <trace/events/power.h>
 #include <linux/cpufreq.h>
-#include <linux/cpuidle.h>
 #include <linux/devfreq.h>
 #include <linux/timer.h>
 

@@ -879,7 +878,6 @@ void dpm_resume_early(pm_message_t state
 void dpm_resume_start(pm_message_t state)
 {
        dpm_resume_noirq(state);
-       cpuidle_resume();
        dpm_resume_early(state);
 }
 EXPORT_SYMBOL_GPL(dpm_resume_start);

@@ -1518,13 +1516,9 @@ int dpm_suspend_end(pm_message_t state)
        if (error)
                goto out;
 
-       cpuidle_pause();
-
        error = dpm_suspend_noirq(state);
-       if (error) {
-               cpuidle_resume();
+       if (error)
                dpm_resume_early(resume_event(state));
-       }
 
 out:
        dpm_show_time(starttime, state, error, "end");

Index: linux-pm/kernel/power/power.h
===================================================================

kernel/power/power.h +14 -0

@@ -4,6 +4,8 @@
 #include <linux/utsname.h>
 #include <linux/freezer.h>
 #include <linux/compiler.h>
+#include <linux/cpu.h>
+#include <linux/cpuidle.h>
 
 struct swsusp_info {
        struct new_utsname      uts;

@@ -310,3 +312,15 @@ extern int pm_wake_lock(const char *buf)
 extern int pm_wake_unlock(const char *buf);
 
 #endif /* !CONFIG_PM_WAKELOCKS */
+
+static inline int pm_sleep_disable_secondary_cpus(void)
+{
+       cpuidle_pause();
+       return suspend_disable_secondary_cpus();
+}
+
+static inline void pm_sleep_enable_secondary_cpus(void)
+{
+       suspend_enable_secondary_cpus();
+       cpuidle_resume();
+}