Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool()

From: Joe Perches <joe@perches.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Minchan Kim <minchan@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Michal Hocko <mhocko@suse.cz>,
	David Rientjes <rientjes@google.com>,
	Linux-MM <linux-mm@kvack.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool()
Date: Wed, 10 Jun 2015 17:48:06 -0700	[thread overview]
Message-ID: <1433983686.32331.35.camel@perches.com> (raw)
In-Reply-To: <20150610235836.GB499@swordfish>

On Thu, 2015-06-11 at 08:58 +0900, Sergey Senozhatsky wrote:
> On (06/10/15 16:59), Dan Streetman wrote:
> > On Tue, Jun 9, 2015 at 8:04 AM, Sergey Senozhatsky
> > <sergey.senozhatsky@gmail.com> wrote:
> > > zpool_destroy_pool() does not tolerate a NULL zpool pointer
> > > argument and performs a NULL-pointer dereference. Although
> > > there is only one zpool_destroy_pool() user (as of 4.1),
> > > still update it to be coherent with the corresponding
> > > destroy() functions of the remainig pool-allocators (slab,
> > > mempool, etc.), which now allow NULL pool-pointers.
> > >
> > > For consistency, tweak zpool_destroy_pool() and NULL-check the
> > > pointer there.
> > >
> > > Proposed by Andrew Morton.
> > >
> > > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> > > Reported-by: Andrew Morton <akpm@linux-foundation.org>
> > > LKML-reference: https://lkml.org/lkml/2015/6/8/583
> > 
> > Acked-by: Dan Streetman <ddstreet@ieee.org>
> 
> Thanks.
> 
> Shall we ask Joe to add zpool_destroy_pool() to the
> "$func(NULL) is safe and this check is probably not required" list?

[]

Is it really worth it?

There isn't any use of zpool_destroy_pool preceded by an if
There is one and only one use of zpool_destroy_pool.