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

Olof Johansson
2007-10-18T14:51:55Z

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@oracle.com> 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;