Subject: preempt-rt: Convert arm boot_lock to raw
From: Frank Rowand <frank.rowand@am.sony.com>
Date: Mon, 19 Sep 2011 14:51:14 -0700


The arm boot_lock is used by the secondary processor startup code.  The locking
task is the idle thread, which has idle->sched_class == &idle_sched_class.
idle_sched_class->enqueue_task == NULL, so if the idle task blocks on the
lock, the attempt to wake it when the lock becomes available will fail:

try_to_wake_up()
   ...
      activate_task()
         enqueue_task()
            p->sched_class->enqueue_task(rq, p, flags)

Fix by converting boot_lock to a raw spin lock.

Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Link: http://lkml.kernel.org/r/4E77B952.3010606@am.sony.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/arm/mach-exynos/platsmp.c    |   12 ++++++------
 arch/arm/mach-msm/platsmp.c       |   10 +++++-----
 arch/arm/mach-omap2/omap-smp.c    |   10 +++++-----
 arch/arm/mach-ux500/platsmp.c     |   10 +++++-----
 arch/arm/plat-versatile/platsmp.c |   10 +++++-----
 5 files changed, 26 insertions(+), 26 deletions(-)

Index: linux-stable/arch/arm/mach-exynos/platsmp.c
===================================================================
--- linux-stable.orig/arch/arm/mach-exynos/platsmp.c
+++ linux-stable/arch/arm/mach-exynos/platsmp.c
@@ -62,7 +62,7 @@ static void __iomem *scu_base_addr(void)
 	return (void __iomem *)(S5P_VA_SCU);
 }
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 void __cpuinit platform_secondary_init(unsigned int cpu)
 {
@@ -82,8 +82,8 @@ void __cpuinit platform_secondary_init(u
 	/*
 	 * Synchronise with the boot thread.
 	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -94,7 +94,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * Set synchronisation state between this boot processor
 	 * and the secondary one
 	 */
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	/*
 	 * The secondary processor is waiting to be released from
@@ -123,7 +123,7 @@ int __cpuinit boot_secondary(unsigned in
 
 		if (timeout == 0) {
 			printk(KERN_ERR "cpu1 power enable failed");
-			spin_unlock(&boot_lock);
+			raw_spin_unlock(&boot_lock);
 			return -ETIMEDOUT;
 		}
 	}
@@ -151,7 +151,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
 	 */
-	spin_unlock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 
 	return pen_release != -1 ? -ENOSYS : 0;
 }
Index: linux-stable/arch/arm/mach-msm/platsmp.c
===================================================================
--- linux-stable.orig/arch/arm/mach-msm/platsmp.c
+++ linux-stable/arch/arm/mach-msm/platsmp.c
@@ -40,7 +40,7 @@ extern void msm_secondary_startup(void);
  */
 volatile int pen_release = -1;
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 static inline int get_core_count(void)
 {
@@ -70,8 +70,8 @@ void __cpuinit platform_secondary_init(u
 	/*
 	 * Synchronise with the boot thread.
 	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 static __cpuinit void prepare_cold_cpu(unsigned int cpu)
@@ -108,7 +108,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * set synchronisation state between this boot processor
 	 * and the secondary one
 	 */
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	/*
 	 * The secondary processor is waiting to be released from
@@ -142,7 +142,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
 	 */
-	spin_unlock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 
 	return pen_release != -1 ? -ENOSYS : 0;
 }
Index: linux-stable/arch/arm/mach-omap2/omap-smp.c
===================================================================
--- linux-stable.orig/arch/arm/mach-omap2/omap-smp.c
+++ linux-stable/arch/arm/mach-omap2/omap-smp.c
@@ -42,7 +42,7 @@
 /* SCU base address */
 static void __iomem *scu_base;
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 void __iomem *omap4_get_scu_base(void)
 {
@@ -73,8 +73,8 @@ void __cpuinit platform_secondary_init(u
 	/*
 	 * Synchronise with the boot thread.
 	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -87,7 +87,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * Set synchronisation state between this boot processor
 	 * and the secondary one
 	 */
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	/*
 	 * Update the AuxCoreBoot0 with boot state for secondary core.
@@ -131,7 +131,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * Now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
 	 */
-	spin_unlock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 
 	return 0;
 }
Index: linux-stable/arch/arm/mach-ux500/platsmp.c
===================================================================
--- linux-stable.orig/arch/arm/mach-ux500/platsmp.c
+++ linux-stable/arch/arm/mach-ux500/platsmp.c
@@ -56,7 +56,7 @@ static void __iomem *scu_base_addr(void)
 	return NULL;
 }
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 void __cpuinit platform_secondary_init(unsigned int cpu)
 {
@@ -76,8 +76,8 @@ void __cpuinit platform_secondary_init(u
 	/*
 	 * Synchronise with the boot thread.
 	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -88,7 +88,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * set synchronisation state between this boot processor
 	 * and the secondary one
 	 */
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	/*
 	 * The secondary processor is waiting to be released from
@@ -109,7 +109,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
 	 */
-	spin_unlock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 
 	return pen_release != -1 ? -ENOSYS : 0;
 }
Index: linux-stable/arch/arm/plat-versatile/platsmp.c
===================================================================
--- linux-stable.orig/arch/arm/plat-versatile/platsmp.c
+++ linux-stable/arch/arm/plat-versatile/platsmp.c
@@ -38,7 +38,7 @@ static void __cpuinit write_pen_release(
 	outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
 }
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 void __cpuinit platform_secondary_init(unsigned int cpu)
 {
@@ -58,8 +58,8 @@ void __cpuinit platform_secondary_init(u
 	/*
 	 * Synchronise with the boot thread.
 	 */
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -70,7 +70,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * Set synchronisation state between this boot processor
 	 * and the secondary one
 	 */
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	/*
 	 * This is really belt and braces; we hold unintended secondary
@@ -100,7 +100,7 @@ int __cpuinit boot_secondary(unsigned in
 	 * now the secondary core is starting up let it run its
 	 * calibrations, then wait for it to finish
 	 */
-	spin_unlock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 
 	return pen_release != -1 ? -ENOSYS : 0;
 }