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From: Christoph Hellwig <hch@infradead.org>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Assuming NULL
Date: Sat, 11 Jun 2005 18:30:35 +0100	[thread overview]
Message-ID: <20050611173035.GA1847@infradead.org> (raw)
In-Reply-To: <Pine.LNX.4.61.0506111823440.19223@yvahk01.tjqt.qr>

On Sat, Jun 11, 2005 at 06:24:22PM +0200, Jan Engelhardt wrote:
> Hi developers,
> 
> 
> 
> some places in fs/*.c have conditions like
> 
> (namei.c, 238, in "int permission()"):
>         if(inode->i_op && inode->i_op->permission)
> 
> Others just have
> (namei.c, 813, in "int fastcall link_path_walk()"):
>         if(!inode->i_op->lookup)
> 
> My question is: Which one is right wrt the case "i_op ==/!= NULL"?
> There are two ways:
> 
> - the kernel assumes i_op (and similar) is always non-NULL
>   => then we can remove a lot of checks, like the first example above

i_op must not be NULL .alloc_inode() intitializes it to &empty_iops,
and setting it to NULL would be a bug.


      parent reply	other threads:[~2005-06-11 17:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-11 16:24 Jan Engelhardt
2005-06-11 16:49 ` Måns Rullgård
2005-06-11 17:17   ` Jan Engelhardt
2005-06-11 17:24 ` Willy Tarreau
2005-06-11 17:30 ` Christoph Hellwig [this message]

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