Re: [PATCH v2 1/2] rtmutex Real-Time Linux: Fixing kernel BUG at kernel/locking/rtmutex.c:997!

From: Thomas Gleixner
Date: Tue Apr 07 2015 - 15:17:15 EST


On Tue, 7 Apr 2015, Jason Low wrote:
> The lock shouldn't be used in get_next_timer_interrupt() either right?
>
> unsigned long get_next_timer_interrupt(unsigned long now)
> {
> ...
>
> #ifdef CONFIG_PREEMPT_RT_FULL
> /*
> * On PREEMPT_RT we cannot sleep here. If the trylock does not
> * succeed then we return the worst-case 'expires in 1 tick'
> * value. We use the rt functions here directly to avoid a
> * migrate_disable() call.
> */
> if (!spin_do_trylock(&base->lock))
> return now + 1;
> #else

And how do you protect the walk of the timer wheel against a
concurrent insertion/removal?

Thanks,

tglx

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