From: Frank Rowand <frank.rowand@xxxxxxxxxxx>
The omap 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.
[ balbi@xxxxxx: taken from RT v3.10.4-rt1 patchset ]
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/arm/mach-omap2/omap-smp.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
index 8708b2a..c4caa18 100644
--- a/arch/arm/mach-omap2/omap-smp.c
+++ b/arch/arm/mach-omap2/omap-smp.c
@@ -44,7 +44,7 @@ u16 pm44xx_errata;
/* 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)
{
@@ -68,8 +68,8 @@ static void omap4_secondary_init(unsigned int cpu)
/*
* Synchronise with the boot thread.
*/
- spin_lock(&boot_lock);
- spin_unlock(&boot_lock);
+ raw_spin_lock(&boot_lock);
+ raw_spin_unlock(&boot_lock);
}
static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
@@ -83,7 +83,7 @@ static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
* 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.
@@ -160,7 +160,7 @@ static int omap4_boot_secondary(unsigned int cpu, struct task_struct *idle)
* 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;
}
--
1.8.3.4.840.g6a90778
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