On 11/4/07, Jens Axboe <[email protected]> wrote:
> On Sat, Nov 03 2007, Jens Axboe wrote:
> > It's probably enough. Only if you use chaining do you need to convert to
> > using for_each_sg() and so on.
>
> Did a grep over ieee1394/, this seems to be all you need.
What *I* need. For eth1394.
Stefan Richter wrote:
> (The other place where the 1394 stack deals with s/g lists is sbp2 where
> we have to deal with what comes from the SCSI stack or the block layer.
> But sbp2's s/g list handling is entirely unrelated to ieee1394's own
> code for isochronous I/O and async streams, which eth1394 needs and
> caused the bug.)
I see nothing preventing chained sg lists to be feed into
sbp2scsi_queuecommand() which then gives these lists to
sbp2_prep_command_orb_sg().
And there I find this:
static void sbp2_prep_command_orb_sg(struct sbp2_command_orb *orb,
struct sbp2_fwhost_info *hi,
struct sbp2_command_info *cmd,
unsigned int scsi_use_sg,
struct scatterlist *sgpnt,
u32 orb_direction,
enum dma_data_direction dma_dir)
{
[snip]
for (i = 0, sg_count = 0 ; i < count; i++, sgpnt++) {
As yesterday my md1_raid5-thread oopsed with the same bug from the
thread "kernel NULL pointer dereference in blk_rq_map_sg with
v2.6.23-6815-g0895e91" I'm rather suspicious of anything sg related
right now. (At least I think its the same bug, as 2.6.23-mm1 does not
contain the fix from that thread)
> diff --git a/drivers/ieee1394/dma.c b/drivers/ieee1394/dma.c
> index f5f4983..7c4eb39 100644
> --- a/drivers/ieee1394/dma.c
> +++ b/drivers/ieee1394/dma.c
> @@ -103,8 +103,7 @@ int dma_region_alloc(struct dma_region *dma, unsigned long n_bytes,
> goto err;
> }
>
> - /* just to be safe - this will become unnecessary once sglist->address goes away */
> - memset(dma->sglist, 0, dma->n_pages * sizeof(*dma->sglist));
> + sg_init_table(dma->sglist, dma->n_pages);
>
> /* fill scatter/gather list with pages */
> for (i = 0; i < dma->n_pages; i++) {
>
With that patch, 2.6.24-rc1-b4f555081fdd27d13e6ff39d455d5aefae9d2c0c
boots, eth1394 works.
Torsten
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