Re: IS_ERR Threshold Value

[H. Peter Anvin]

Randy.Dunlap wrote:
> On Wed, 28 Jun 2006 14:57:07 -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.  
> >
> > I've supplied a patch that addresses this situation by changing the
> > threshold used by IS_ERR if EMAXERRNO is defined and greater than 1000. 
> > Perhaps permanently raising the threshold value to something >1133 is
> > sufficient.
> >
> > Looking forward to your feedback.  
> >
> > Erik Frederiksen
> > Firmware Design Engineer Co-op
> > PMC-Sierra Saskatoon
>
> Hi,
> Peter Anvin mentioned just a few days ago that this threshold value
> should be 4095 for all arches.  I think we need to get that patch
> done & submitted to Andrew for -mm.

Indeed.

	-hpa
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