suspend-Prevent-might-sleep-splats.patch

From bf887addbb3fd6dc0ec6bfbe8fbfe45009eb11af Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 15 Jul 2010 10:29:00 +0200
Subject: [PATCH] suspend: Prevent might sleep splats

commit 60f778fcfc89524ece9fedbd8ae3eecd58adb221 in tip.

timekeeping suspend/resume calls read_persistant_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 temporary 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().

Needs to be revisited.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 include/linux/kernel.h   |    2 +-
 kernel/power/hibernate.c |    6 ++++++
 kernel/power/suspend.c   |    4 ++++
 3 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 5215fbe..f5fe8b6 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -337,7 +337,7 @@ extern enum system_states {
 	SYSTEM_HALT,
 	SYSTEM_POWER_OFF,
 	SYSTEM_RESTART,
-	SYSTEM_SUSPEND_DISK,
+	SYSTEM_SUSPEND,
 } system_state;
 
 #define TAINT_PROPRIETARY_MODULE	0
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index aa9e916..295ad3d 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -270,6 +270,8 @@ static int create_image(int platform_mode)
 
 	local_irq_disable();
 
+	system_state = SYSTEM_SUSPEND;
+
 	error = sysdev_suspend(PMSG_FREEZE);
 	if (error) {
 		printk(KERN_ERR "PM: Some system devices failed to power down, "
@@ -298,6 +300,7 @@ static int create_image(int platform_mode)
 	 */
 
  Enable_irqs:
+	system_state = SYSTEM_RUNNING;
 	local_irq_enable();
 
  Enable_cpus:
@@ -393,6 +396,7 @@ static int resume_target_kernel(bool platform_mode)
 		goto Enable_cpus;
 
 	local_irq_disable();
+	system_state = SYSTEM_SUSPEND;
 
 	error = sysdev_suspend(PMSG_QUIESCE);
 	if (error)
@@ -424,6 +428,7 @@ static int resume_target_kernel(bool platform_mode)
 	sysdev_resume();
 
  Enable_irqs:
+	system_state = SYSTEM_RUNNING;
 	local_irq_enable();
 
  Enable_cpus:
@@ -510,6 +515,7 @@ int hibernation_platform_enter(void)
 		goto Platform_finish;
 
 	local_irq_disable();
+	system_state = SYSTEM_SUSPEND;
 	sysdev_suspend(PMSG_HIBERNATE);
 	hibernation_ops->enter();
 	/* We should never get here */
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 56e7dbb..5570a49 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -155,6 +155,8 @@ static int suspend_enter(suspend_state_t state)
 	arch_suspend_disable_irqs();
 	BUG_ON(!irqs_disabled());
 
+	system_state = SYSTEM_SUSPEND;
+
 	error = sysdev_suspend(PMSG_SUSPEND);
 	if (!error) {
 		if (!suspend_test(TEST_CORE))
@@ -162,6 +164,8 @@ static int suspend_enter(suspend_state_t state)
 		sysdev_resume();
 	}
 
+	system_state = SYSTEM_RUNNING;
+
 	arch_suspend_enable_irqs();
 	BUG_ON(irqs_disabled());
 
-- 
1.7.0.4