Re: [patch] lockdep: annotate mm/slab.c

[Linus Torvalds <torvalds@osdl.org>]

On Thu, 13 Jul 2006, Ingo Molnar wrote:
>  
> +#ifdef CONFIG_LOCKDEP
> +
> +/*
> + * Slab sometimes uses the kmalloc slabs to store the slab headers
> + * for other slabs "off slab".
> + * The locking for this is tricky in that it nests within the locks
> + * of all other slabs in a few places; to deal with this special
> + * locking we put on-slab caches into a separate lock-class.
> + */
> +static struct lock_class_key on_slab_key;
> +
> +static inline void init_lock_keys(struct cache_sizes *s)
> +{
> +	int q;
> +
> +	for (q = 0; q < MAX_NUMNODES; q++) {
> +		if (!s->cs_cachep->nodelists[q] || OFF_SLAB(s->cs_cachep))
> +			continue;
> +		lockdep_set_class(&s->cs_cachep->nodelists[q]->list_lock,
> +				  &on_slab_key);
> +	}
> +}
> +
> +#else
> +static inline void init_lock_keys(struct cache_sizes *s)
> +{
> +}
> +#endif

Why isn't the "on_slab_key" local to just the init_lock_keys() function, 
and the #ifdef around it all?

Ie just

	static inline void init_lock_keys(struct cache_sizes *s)
	{
	#ifdef CONFIG_LOCKDEP
		static struct lock_class_key on_slab_key;
		int q;

		for (q = 0; q < MAX_NUMNODES; q++) {
			...
	#endif CONFIG_LOCKDEP
	}

instead?

		Linus
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