linux-kernel - Re: [PATCH] jffs2: Remove NULL checks from jffs2_destroy_slab_caches

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Message-ID: <20150806141718.GA4292@swordfish>
Date:	Thu, 6 Aug 2015 23:17:18 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Julia Lawall <julia.lawall@...6.fr>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Brian Norris <computersforpeace@...il.com>,
	Salah Triki <salah.triki@....org>, dwmw2@...radead.org,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] jffs2: Remove NULL checks from jffs2_destroy_slab_caches

On (08/06/15 08:16), Julia Lawall wrote:
> > 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@...il.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@....org>".
> > 
> > For the record, this is the second, let's say strange, patch from Salah
> > that I see today.
> 
> I'm missing some context.  As far as I can see, kmem_cache_destroy is 
> updated in linux-next.  So it seems like it could be OK to submit a patch 
> to clean up the uses now.  Does Salah's patch address all three functions: 
> kmem_cache_destroy, mempool_destroy, and dma_pool_destroy?
> 

no, just one that you already published.

all 3 functions are updated in -next, so you are welcome to send
your patch set.

	-ss

> > 
> > 	-ss
> > 
> > > > Signed-off-by: Salah Triki <salah.triki@....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/
> > > 
> > 
> 
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