[PATCH] make mempool_destroy resilient against NULL pointers.

[PATCH] make mempool_destroy resilient against NULL pointers.

[Jesper Juhl]

General rule (as I understand it) is that functions that free resources 
should handle being passed NULL pointers - mempool_destroy() will 
currently explode if passed a NULL pointer, the patch below makes it safe 
to pass it NULL.

Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
---

 mempool.c |    2 ++
 1 files changed, 2 insertions(+)


--- linux-2.6.12-rc2-mm2-orig/mm/mempool.c	2005-04-05 21:21:56.000000000 +0200
+++ linux-2.6.12-rc2-mm2/mm/mempool.c	2005-04-09 03:33:58.000000000 +0200
@@ -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);

Re: [PATCH] make mempool_destroy resilient against NULL pointers.

[Andrew Morton]

Jesper Juhl <juhl-lkml@dif.dk> wrote:
>
> 
> General rule (as I understand it) is that functions that free resources 
> should handle being passed NULL pointers - mempool_destroy() will 
> currently explode if passed a NULL pointer, the patch below makes it safe 
> to pass it NULL.

The best response to mempool_destroy(0) is an oops.  There's no legitimate
reason for doing it.

Re: [PATCH] make mempool_destroy resilient against NULL pointers.

[Jesper Juhl]

On Fri, 8 Apr 2005, Andrew Morton wrote:

> Jesper Juhl <juhl-lkml@dif.dk> wrote:
> >
> > 
> > General rule (as I understand it) is that functions that free resources 
> > should handle being passed NULL pointers - mempool_destroy() will 
> > currently explode if passed a NULL pointer, the patch below makes it safe 
> > to pass it NULL.
> 
> The best response to mempool_destroy(0) is an oops.  There's no legitimate
> reason for doing it.
> 
Ok, ignore the patch then.

-- 
Jesper

Re: [PATCH] make mempool_destroy resilient against NULL pointers.

[Jesper Juhl]

On Fri, 8 Apr 2005, Andrew Morton wrote:

> Jesper Juhl <juhl-lkml@dif.dk> wrote:
> >
> > 
> > General rule (as I understand it) is that functions that free resources 
> > should handle being passed NULL pointers - mempool_destroy() will 
> > currently explode if passed a NULL pointer, the patch below makes it safe 
> > to pass it NULL.
> 
> The best response to mempool_destroy(0) is an oops.  There's no legitimate
> reason for doing it.
> 
Sorry to bring this up again but, take a look at the patch by 
ecashin@coraid.com titled "[PATCH] aoe 5/12: don't try to free null 
bufpool" http://grmso.net:8090/commit/03347936afcba990525736ae39daa13f643eac5f/diff/fa83c2ddd4293bd8bcaeeaf14bfdbf2fbe810420/
That's exactely the reason why the patch I submitted should be applied, to 
avoid having to do such checks all over the place in other code and 
instead just do it in one location. With this patch in place, the patch to 
aoedev.c would not have been needed.

Or am I still misunderstanding something.

-- 
Jesper