Re: IS_ERR Threshold Value

[Nathan Scott <nathans@sgi.com>]

Hi Erik,

On Wed, Jun 28, 2006 at 02:57:07PM -0600, Erik Frederiksen wrote:
> 
> from include/asm-mips/errno.h
> #define EDQUOT      1133    /* Quota exceeded */
> 
> I noticed that the errno value for EDQUOT on MIPS is considerably larger
> than all others.  This can lead to a situation where functions using
> ERR_PTR() to return error codes in pointers cannot return this error
> code without IS_ERR() thinking that the pointer is valid.  In my case,
> it caused an alignment exception in the XFS open call when quota has
> been exceeded in the linux-mips 2.6.14 kernel.  I think that the XFS
> code has changed enough that this bug isn't in newer versions, though I
> haven't done a thorough investigation.  

Hmm, I'm not sure I understand the XFS side of your report here - on
open, for quota to be coming into play we must be creating a new inode
and those code paths inside XFS have no use of IS_ERR/ERR_PTR magic...
did you mean there's generic problems here (I can see those macros are
used in the generic VFS open() code) ... or am I missing your point?

thanks.

-- 
Nathan