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SubjectRe: [PATCH] ledtrig-cpu: use spin_lock to replace mutex lock
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Hi Bryan,

On Thu, 2012-10-18 at 11:18 -0700, Bryan Wu wrote:
> @@ -117,14 +117,14 @@ static int __init ledtrig_cpu_init(void)
> for_each_possible_cpu(cpu) {
> struct led_trigger_cpu *trig = &per_cpu(cpu_trig, cpu);
>
> - mutex_init(&trig->lock);
> + spin_lock_init(&trig->lock);
>
> snprintf(trig->name, MAX_NAME_LEN, "cpu%d", cpu);
>
> - mutex_lock(&trig->lock);
> + spin_lock(&trig->lock);
> led_trigger_register_simple(trig->name, &trig->_trig);
> trig->lock_is_inited = 1;
> - mutex_unlock(&trig->lock);
> + spin_unlock(&trig->lock);

I wouldn't know how to fix the original problem, but I don't think this
patch is okay -- led_trigger_register_simple() does things that
potentially sleep (GFP_KERNEL allocation, down_write), so it's not safe
to call while holding a spinlock.




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