Re: [PATCH 2.6.11] aoe [5/12]: don't try to free null bufpool

[Jesper Juhl]

On Thu, 24 Mar 2005, Arjan van de Ven wrote:

> On Thu, 2005-03-24 at 09:04 -0800, ecashin@xxxxxxxxxxxx wrote:
> > Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:
> > 
> > > On Thu, 2005-03-24 at 07:17 -0800, ecashin@xxxxxxxxxxxx wrote:
> > >> don't try to free null bufpool
> > >
> > > in linux there is a "rule" that all memory free routines are supposed to
> > > also accept NULL as argument, so I think this patch is not needed (and
> > > even wrong)
> > >
> > 
> > Hmm.  The mm/mempool.c:mempool_destroy function immediately
> > dereferences the pointer passed to it:
> > 
> > void mempool_destroy(mempool_t *pool)
> > {
> > 	if (pool->curr_nr != pool->min_nr)
> > 		BUG();		/* There were outstanding elements */
> > 	free_pool(pool);
> > }
> > 
> > ... so I'm not sure mempool_destroy fits the rule.  Are you suggesting
> > that the patch should instead modify mempool_destroy?
> 
> hmm perhaps... Jens?
> 

Having mempool_destroy() be the one that checks seems safer, then callers 
won't forget to check - easier to just check in one place.
If that's what you want, then here's a patch. If this is acceptable I can 
create another one that removes the (then pointless) NULL checks from all 
callers - let me know if that's wanted.

Signed-off-by: Jesper Juhl <juhl-lkml@xxxxxx>

--- linux-2.6.12-rc1-mm3-orig/mm/mempool.c	2005-03-21 23:12:43.000000000 +0100
+++ linux-2.6.12-rc1-mm3/mm/mempool.c	2005-03-25 15:34:04.000000000 +0100
@@ -176,6 +176,8 @@ EXPORT_SYMBOL(mempool_resize);
  */
 void mempool_destroy(mempool_t *pool)
 {
+	if (!pool)
+		return;
 	if (pool->curr_nr != pool->min_nr)
 		BUG();		/* There were outstanding elements */
 	free_pool(pool);


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