Commit c1a957d1 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Rafael J. Wysocki
Browse files

PM / suspend: Prevent might sleep splats 



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: default avatarThomas Gleixner <tglx@linutronix.de>
[bigeasy: cover s2idle in tick_freeze() / tick_unfreeze()]
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 771c577c

include/linux/kernel.h

+1 −0
Original line number Diff line number Diff line
@@ -542,6 +542,7 @@ extern enum system_states { 
	SYSTEM_HALT,

	SYSTEM_POWER_OFF,

	SYSTEM_RESTART,

	SYSTEM_SUSPEND,

} system_state;



/* This cannot be an enum because some may be used in assembly source. */

kernel/power/hibernate.c

+7 −0
Original line number Diff line number Diff line
@@ -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:

kernel/power/suspend.c

+4 −0
Original line number Diff line number Diff line
@@ -428,6 +428,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup) 
	arch_suspend_disable_irqs();

	BUG_ON(!irqs_disabled());



	system_state = SYSTEM_SUSPEND;



	error = syscore_suspend();

	if (!error) {

		*wakeup = pm_wakeup_pending();
@@ -443,6 +445,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup) 
		syscore_resume();

	}



	system_state = SYSTEM_RUNNING;



	arch_suspend_enable_irqs();

	BUG_ON(irqs_disabled());

kernel/time/tick-common.c

+2 −0
Original line number Diff line number Diff line
@@ -490,6 +490,7 @@ void tick_freeze(void) 
	if (tick_freeze_depth == num_online_cpus()) {

		trace_suspend_resume(TPS("timekeeping_freeze"),

				     smp_processor_id(), true);

		system_state = SYSTEM_SUSPEND;

		timekeeping_suspend();

	} else {

		tick_suspend_local();
@@ -513,6 +514,7 @@ void tick_unfreeze(void) 


	if (tick_freeze_depth == num_online_cpus()) {

		timekeeping_resume();

		system_state = SYSTEM_RUNNING;

		trace_suspend_resume(TPS("timekeeping_freeze"),

				     smp_processor_id(), false);

	} else {

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