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Subject[PATCH 1/4] PM / suspend: Prevent might sleep splats
Date
From: Thomas Gleixner <tglx@linutronix.de>

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().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bigeasy: cover s2idle]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/kernel.h | 1 +
kernel/power/hibernate.c | 7 +++++++
kernel/power/suspend.c | 6 ++++++
3 files changed, 14 insertions(+)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 6a1eb0b0aad9..7aed92624531 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -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. */
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 5454cc639a8d..9c85c7822383 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -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:
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 4c10be0f4843..9108a99878bf 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -110,6 +110,7 @@ static void s2idle_loop(void)
{
pm_pr_dbg("suspend-to-idle\n");

+ system_state = SYSTEM_SUSPEND;
for (;;) {
int error;

@@ -148,6 +149,7 @@ static void s2idle_loop(void)

pm_wakeup_clear(false);
}
+ system_state = SYSTEM_RUNNING;

pm_pr_dbg("resume from suspend-to-idle\n");
}
@@ -428,6 +430,8 @@ 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 +447,8 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
syscore_resume();
}

+ system_state = SYSTEM_RUNNING;
+
arch_suspend_enable_irqs();
BUG_ON(irqs_disabled());

--
2.17.0
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