Re: [S+Q 07/16] slub: discard_slab_unlock

[David Rientjes <rientjes@google.com>]

On Fri, 25 Jun 2010, Christoph Lameter wrote:

> The sequence of unlocking a slab and freeing occurs multiple times.
> Put the common into a single function.
> 

Did you want to respond to the comments I made about this patch at 
http://marc.info/?l=linux-mm&m=127689747432061 ?  Specifically, how it 
makes seeing if there are unmatched slab_lock() -> slab_unlock() pairs 
more difficult.

> Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
> 
> ---
>  mm/slub.c |   16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c	2010-06-01 08:58:50.000000000 -0500
> +++ linux-2.6/mm/slub.c	2010-06-01 08:58:54.000000000 -0500
> @@ -1260,6 +1260,13 @@ static __always_inline int slab_trylock(
>  	return rc;
>  }
>  
> +static void discard_slab_unlock(struct kmem_cache *s,
> +	struct page *page)
> +{
> +	slab_unlock(page);
> +	discard_slab(s, page);
> +}
> +
>  /*
>   * Management of partially allocated slabs
>   */
> @@ -1437,9 +1444,8 @@ static void unfreeze_slab(struct kmem_ca
>  			add_partial(n, page, 1);
>  			slab_unlock(page);
>  		} else {
> -			slab_unlock(page);
>  			stat(s, FREE_SLAB);
> -			discard_slab(s, page);
> +			discard_slab_unlock(s, page);
>  		}
>  	}
>  }
> @@ -1822,9 +1828,8 @@ slab_empty:
>  		remove_partial(s, page);
>  		stat(s, FREE_REMOVE_PARTIAL);
>  	}
> -	slab_unlock(page);
>  	stat(s, FREE_SLAB);
> -	discard_slab(s, page);
> +	discard_slab_unlock(s, page);
>  	return;
>  
>  debug:
> @@ -2893,8 +2898,7 @@ int kmem_cache_shrink(struct kmem_cache 
>  				 */
>  				list_del(&page->lru);
>  				n->nr_partial--;
> -				slab_unlock(page);
> -				discard_slab(s, page);
> +				discard_slab_unlock(s, page);
>  			} else {
>  				list_move(&page->lru,
>  				slabs_by_inuse + page->inuse);

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