From: Frank Rowand <frank.rowand@xxxxxxxxxxx>
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.
Cc: David Brown <davidb@xxxxxxxxxxxxxx>
Cc: Daniel Walker <dwalker@xxxxxxxxxx>
Cc: Bryan Huntsman <bryanh@xxxxxxxxxxxxxx>
Cc: linux-arm-msm@xxxxxxxxxxxxxxx
Cc: Frank Rowand <frank.rowand@xxxxxxxxxxxxxx>
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/4E77B952.3010606@xxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
arch/arm/mach-msm/platsmp.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-msm/platsmp.c b/arch/arm/mach-msm/platsmp.c
index 3f06edc..fc09a04 100644
--- a/arch/arm/mach-msm/platsmp.c
+++ b/arch/arm/mach-msm/platsmp.c
@@ -30,7 +30,7 @@
extern void msm_secondary_startup(void);
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
static inline int get_core_count(void)
{
@@ -50,8 +50,8 @@ static void msm_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 void prepare_cold_cpu(unsigned int cpu)
@@ -88,7 +88,7 @@ static int msm_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);
/*
* The secondary processor is waiting to be released from
@@ -122,7 +122,7 @@ static int msm_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 pen_release != -1 ? -ENOSYS : 0;
}
--
1.8.5.1
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