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PM / suspend: Prevent might sleep splats

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timekeeping suspend/resume calls read_persistent_clock() which takes
rtc_lock. That results in might sleep warnings because at that point
we run with interrupts disabled.

We cannot convert rtc_lock to a raw spinlock as that would trigger
other might sleep warnings.

As a workaround we disable the might sleep warnings by setting
system_state to SYSTEM_SUSPEND before calling sysdev_suspend() and
restoring it to SYSTEM_RUNNING afer sysdev_resume(). There is no lock
contention because hibernate / suspend to RAM is single-CPU at this
point.

In s2idle's case the system_state is set to SYSTEM_SUSPEND before
timekeeping_suspend() which is invoked by the last CPU. In the resume
case it set back to SYSTEM_RUNNING after timekeeping_resume() which is
invoked by the first CPU in the resume case. The other CPUs will block
on tick_freeze_lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: cover s2idle in tick_freeze() / tick_unfreeze()]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Thomas Gleixner 2018-05-25 17:54:41 +02:00 • committed by Rafael J. Wysocki
parent 771c577c23
commit c1a957d170
4 changed files with 14 additions and 0 deletions
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7
kernel/power/hibernate.c
View file

@ -287,6 +287,8 @@ static int create_image(int platform_mode)
local_irq_disable();
system_state = SYSTEM_SUSPEND;
error = syscore_suspend();
if (error) {
pr_err("Some system devices failed to power down, aborting hibernation\n");
@ -317,6 +319,7 @@ static int create_image(int platform_mode)
syscore_resume();
Enable_irqs:
system_state = SYSTEM_RUNNING;
local_irq_enable();
Enable_cpus:
@ -445,6 +448,7 @@ static int resume_target_kernel(bool platform_mode)
goto Enable_cpus;
local_irq_disable();
system_state = SYSTEM_SUSPEND;
error = syscore_suspend();
if (error)
@ -478,6 +482,7 @@ static int resume_target_kernel(bool platform_mode)
syscore_resume();
Enable_irqs:
system_state = SYSTEM_RUNNING;
local_irq_enable();
Enable_cpus:
@ -563,6 +568,7 @@ int hibernation_platform_enter(void)
goto Enable_cpus;
local_irq_disable();
system_state = SYSTEM_SUSPEND;
syscore_suspend();
if (pm_wakeup_pending()) {
error = -EAGAIN;
@ -575,6 +581,7 @@ int hibernation_platform_enter(void)
Power_up:
syscore_resume();
system_state = SYSTEM_RUNNING;
local_irq_enable();
Enable_cpus: