Re: [PATCH] jffs2: Remove NULL checks from jffs2_destroy_slab_caches

From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Brian Norris <computersforpeace@gmail.com>
Cc: Salah Triki <salah.triki@acm.org>,
	dwmw2@infradead.org, linux-mtd@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Julia Lawall <julia.lawall@lip6.fr>
Subject: Re: [PATCH] jffs2: Remove NULL checks from jffs2_destroy_slab_caches
Date: Wed, 5 Aug 2015 22:32:47 +0900	[thread overview]
Message-ID: <20150805133247.GB576@swordfish> (raw)
In-Reply-To: <20150804200639.GP10676@google.com>

Hi,

Cc Julia Lawall

On (08/04/15 13:06), Brian Norris wrote:
> On Tue, Aug 04, 2015 at 08:46:30PM +0100, Salah Triki wrote:
> > kmem_cache_destroy can be called with NULL values. Thus, the checks that
> > precede the calls are useless.
> 
> This isn't *currently* true. Only after a bit of work did I find that
> this is queued to change in the next release -- akpm has a patch:
> 
> commit 3e54c0cd3abdca0cf91854278c8633fc7df6beb1
> Author: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> Date:   Thu Jul 30 09:55:36 2015 +1000
> 
>     mm/slab_common: allow NULL cache pointer in kmem_cache_destroy()
> 
> Please provide the appropriate context next time. And for the moment, I will
> not apply this, because this does not work on the current MTD development tree.
> Try your patch bomb on the next release, as it's not worth my time to
> cross-merge a -next branch just for a "cleanup".
> 

Julia already has a patch set to cleanup all the existing users
(not published yet, though).

Apart from that, and this is more important, the patch in question
looks to me as 100% copy paste of a patch by Julia Lawall.

https://lkml.org/lkml/2015/6/10/31

And no, Salah, it's not "Signed-off-by: Salah Triki <salah.triki@acm.org>".

For the record, this is the second, let's say strange, patch from Salah
that I see today.

	-ss

> > Signed-off-by: Salah Triki <salah.triki@acm.org>
> > ---
> >  fs/jffs2/malloc.c | 27 +++++++++------------------
> >  1 file changed, 9 insertions(+), 18 deletions(-)
> > 
> > diff --git a/fs/jffs2/malloc.c b/fs/jffs2/malloc.c
> > index b8fd651..ce11897 100644
> > --- a/fs/jffs2/malloc.c
> > +++ b/fs/jffs2/malloc.c
> > @@ -97,25 +97,16 @@ int __init jffs2_create_slab_caches(void)
> >  
> >  void jffs2_destroy_slab_caches(void)
> >  {
> > -	if(full_dnode_slab)
> > -		kmem_cache_destroy(full_dnode_slab);
> > -	if(raw_dirent_slab)
> > -		kmem_cache_destroy(raw_dirent_slab);
> > -	if(raw_inode_slab)
> > -		kmem_cache_destroy(raw_inode_slab);
> > -	if(tmp_dnode_info_slab)
> > -		kmem_cache_destroy(tmp_dnode_info_slab);
> > -	if(raw_node_ref_slab)
> > -		kmem_cache_destroy(raw_node_ref_slab);
> > -	if(node_frag_slab)
> > -		kmem_cache_destroy(node_frag_slab);
> > -	if(inode_cache_slab)
> > -		kmem_cache_destroy(inode_cache_slab);
> > +	kmem_cache_destroy(full_dnode_slab);
> > +	kmem_cache_destroy(raw_dirent_slab);
> > +	kmem_cache_destroy(raw_inode_slab);
> > +	kmem_cache_destroy(tmp_dnode_info_slab);
> > +	kmem_cache_destroy(raw_node_ref_slab);
> > +	kmem_cache_destroy(node_frag_slab);
> > +	kmem_cache_destroy(inode_cache_slab);
> >  #ifdef CONFIG_JFFS2_FS_XATTR
> > -	if (xattr_datum_cache)
> > -		kmem_cache_destroy(xattr_datum_cache);
> > -	if (xattr_ref_cache)
> > -		kmem_cache_destroy(xattr_ref_cache);
> > +	kmem_cache_destroy(xattr_datum_cache);
> > +	kmem_cache_destroy(xattr_ref_cache);
> >  #endif
> >  }
> >  
> > -- 
> > 1.9.1
> > 
> > 
> > ______________________________________________________
> > Linux MTD discussion mailing list
> > http://lists.infradead.org/mailman/listinfo/linux-mtd/
> 