Re: Assuming NULL

[Christoph Hellwig]

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.

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