Re: [bug] ata subsystem related crash with latest -git

[Olof Johansson]

On Thu, Oct 18, 2007 at 04:38:36PM +0200, Jens Axboe wrote:
> On Thu, Oct 18 2007, Benny Halevy wrote:
> > On Oct. 18, 2007, 16:05 +0200, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
> > > On Thu, Oct 18 2007, Jens Axboe wrote:
> > >> On Thu, Oct 18 2007, Benny Halevy wrote:
> > >>>>  	return sg;
> > >>>>  }
> > >>>> @@ -83,6 +96,9 @@ static inline struct scatterlist *sg_last(struct scatterlist *sgl,
> > >>>>  		ret = sg;
> > >>>>  
> > >>>>  #endif
> > >>>> +#ifdef CONFIG_DEBUG_SG
> > >>>> +	BUG_ON(sgl[0].sg_magic != SG_MAGIC);
> > >>> can it also do BUG_ON(!sg_is_last(sg))?
> > >> That would make sense, definitely. I'll add that.
> > > 
> > >         BUG_ON(!sg_is_last(ret));
> > > 
> > > it should be, not sg. That's what I merged.
> > > 
> > right. of course.
> 
> OK, that found something interesting - mapping a request may shrink it,
> so we need to update the end marker to move it earlier in the list.
> Basically just a
> 
>         if (sg)
>                 __sg_mark_end(sg);
> 
> at the bottom of blk_rq_map_sg(). Updated patch below, booted on other
> machines now as well without incident.

PPC needs this. I'm guessing other arches might too. Otherwise seems to boot
and work well (with Jeff's sata patch).


Thanks,

-Olof

diff --git a/include/asm-powerpc/scatterlist.h b/include/asm-powerpc/scatterlist.h
index b9f1dbc..fcf7d55 100644
--- a/include/asm-powerpc/scatterlist.h
+++ b/include/asm-powerpc/scatterlist.h
@@ -14,6 +14,9 @@
 #include <asm/dma.h>
 
 struct scatterlist {
+#ifdef CONFIG_DEBUG_SG
+	unsigned long sg_magic;
+#endif
 	unsigned long page_link;
 	unsigned int offset;
 	unsigned int length;
-
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