On Fri, 2016-06-10 at 14:01 -0700, James Bottomley wrote:
> On Fri, 2016-06-10 at 16:58 -0400, Ewan D. Milne wrote:
> > I'm not sure if this is the problem, but the tagging changes to
> > scsi_tcq.h may have altered the 53c700 driver's assumptions.
> > In one case it sets sdev->current_cmnd and then some of the
> > tagging calls would return it if the tag was SCSI_NO_TAG.
> >
> > NCR_700_queuecommand_lck() does:
> >
> > if ((hostdata->tag_negotiated & (1<<scmd_id(SCp))) &&
> > SCp->device->simple_tags) {
> > slot->tag = SCp->request->tag;
> > CDEBUG(KERN_DEBUG, SCp, "sending out tag %d, slot
> > %p\n",
> > slot->tag, slot);
> > } else {
> > slot->tag = SCSI_NO_TAG;
> > /* must populate current_cmnd for
> > scsi_host_find_tag
> > to
> > work */
> > SCp->device->current_cmnd = SCp;
> > }
>
> Thanks ... I was just about to look for something this. I'd got to
> interpreting the script as reselected with tag information present
> and then trying to look the command up with no tag present, hence the
> BUG().
Yes, you're right, it's
commit 64d513ac31bd02a3c9b69ef04444f36c196f9a9d
Author: Christoph Hellwig <hch@xxxxxx>
Date: Thu Oct 8 09:28:04 2015 +0100
scsi: use host wide tags by default
Again. This time because it's transformation of the handling of
SCSI_NO_TAG is wrong. You can't replace the return sdev->current_cmnd
original in scsi_find_tag with the NULL return in scsi_find_host_tag.
I think this changesets wins the prize for the greatest number of
generated faults.
Does this fix 53c700.c?
I suppose we'd better look for other places where no tag fell through
...
James
---
diff --git a/drivers/scsi/53c700.c b/drivers/scsi/53c700.c
index d4c2856..3ddc85e 100644
--- a/drivers/scsi/53c700.c
+++ b/drivers/scsi/53c700.c
@@ -1122,7 +1122,7 @@ process_script_interrupt(__u32 dsps, __u32 dsp, struct scsi_cmnd *SCp,
} else {
struct scsi_cmnd *SCp;
- SCp = scsi_host_find_tag(SDp->host, SCSI_NO_TAG);
+ SCp = SDp->current_cmnd;
if(unlikely(SCp == NULL)) {
sdev_printk(KERN_ERR, SDp,
"no saved request for untagged cmd\n");
@@ -1826,7 +1826,7 @@ NCR_700_queuecommand_lck(struct scsi_cmnd *SCp, void (*done)(struct scsi_cmnd *)
slot->tag, slot);
} else {
slot->tag = SCSI_NO_TAG;
- /* must populate current_cmnd for scsi_host_find_tag to work */
+ /* save current command for reselection */
SCp->device->current_cmnd = SCp;
}
/* sanity check: some of the commands generated by the mid-layer
--
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