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SubjectRe: [PATCH 10/11] qspinlock: Paravirt support
Il 15/06/2014 14:47, Peter Zijlstra ha scritto:
>
>
> #if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
>
> -#define queue_spin_unlock queue_spin_unlock
> /**
> * queue_spin_unlock - release a queue spinlock
> * @lock : Pointer to queue spinlock structure
> *
> * An effective smp_store_release() on the least-significant byte.
> */
> -static inline void queue_spin_unlock(struct qspinlock *lock)
> +static inline void native_queue_unlock(struct qspinlock *lock)
> {
> barrier();
> ACCESS_ONCE(*(u8 *)lock) = 0;
> }
>
> +#else
> +
> +static inline void native_queue_unlock(struct qspinlock *lock)
> +{
> + atomic_dec(&lock->val);
> +}
> +
> #endif /* !CONFIG_X86_OOSTORE && !CONFIG_X86_PPRO_FENCE */


Should be (part of) an earlier patch? Also, does it get wrong if
(CONFIG_X86_OOSTORE || CONFIG_X86_PPRO_FENCE) && paravirt patches the
unlock to a single movb? Of course the paravirt spinlocks could simply
depend on !CONFIG_X86_OOSTORE && !CONFIG_X86_PPRO_FENCE.

> +
> +#define INVALID_HEAD -1
> +#define NO_HEAD nr_cpu_ids
> +

-2, like Waiman said.

Paolo


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