Re: [PATCH 1/2] kref: add kref_test_and_get

[Eric Dumazet]

Le mardi 04 janvier 2011 Ã 16:52 +0100, Jerome Marchand a Ãcrit :
> Add kref_test_and_get() function, which atomically add a reference only if
> refcount is not zero. This prevent to add a reference to an object that is
> already being removed.
> 
> Signed-off-by: Jerome Marchand <jmarchan@xxxxxxxxxx>

> +int kref_test_and_get(struct kref *kref)
> +{
> +	int ret;
> +	smp_mb__before_atomic_inc();
> +	ret = atomic_inc_not_zero(&kref->refcount);
> +	smp_mb__after_atomic_inc();
> +	return ret;
> +}
> +
> +/**

atomic_inc_not_zero() has full memory barrier semantic already, you dont
need smp_mb__before_atomic_inc() or smp_mb__after_atomic_inc();



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