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

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  Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in  zpool_destroy_pool() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-06-11 02:00 +0200
    Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in  zpool_destroy_pool() Joe Perches <joe@perches.com> - 2015-06-11 02:50 +0200
      Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in  zpool_destroy_pool() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-06-11 03:00 +0200
        Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool() Dan Streetman <ddstreet@ieee.org> - 2015-06-11 03:10 +0200

#1162944 — Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool()

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?

	-ss

> > ---
> >  mm/zpool.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/mm/zpool.c b/mm/zpool.c
> > index bacdab6..2f59b90 100644
> > --- a/mm/zpool.c
> > +++ b/mm/zpool.c
> > @@ -202,6 +202,9 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
> >   */
> >  void zpool_destroy_pool(struct zpool *zpool)
> >  {
> > +       if (unlikely(!zpool))
> > +               return;
> > +
> >         pr_info("destroying pool type %s\n", zpool->type);
> >
> >         spin_lock(&pools_lock);
> > --
> > 2.4.3.368.g7974889
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@kvack.org.  For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> 
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#1162953

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.


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#1162957

On (06/10/15 17:48), Joe Perches wrote:
[..]
> > > > 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.
> 

Yes, that's why I asked. I don't think that zpool_destroy_pool()
will gain any significant amount of users soon (well, who knows),
so I'm fine with keeping it out of checkpatch checks. Just checked
your opinion.

	-ss
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#1162960 — Re: [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool()

On Wed, Jun 10, 2015 at 8:59 PM, Sergey Senozhatsky
<sergey.senozhatsky.work@gmail.com> wrote:
> On (06/10/15 17:48), Joe Perches wrote:
> [..]
>> > > > 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.
>>
>
> Yes, that's why I asked. I don't think that zpool_destroy_pool()
> will gain any significant amount of users soon (well, who knows),
> so I'm fine with keeping it out of checkpatch checks. Just checked
> your opinion.

I really doubt if zpool will be used by anyone other than zswap anytime soon.

>
>         -ss
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