On Thu, 20 Mar 2014, James Bottomley wrote:
> > I tried this patch first, because fixing the earlier bug would mask
> > this one.
> >
> > The patch sort of worked. But the first time I tried it, it failed in
> > a rather amusing way. While the second retry was running and hung,
> > scmd->result _was_ equal to CHECK_CONDITION -- because that was the
> > result from the _first_ retry, and it had never gotten cleared!
> >
> > scmd->result needs to be set to 0 before the queuecommand callback is
> > invoked. I ended up adding this to your patch, and then it worked
> > perfectly:
>
> Wow, the stale data bugs are just crawling out of the code. Thanks for
> checking.
>
> >
> > Index: usb-3.14/drivers/scsi/scsi_error.c
> > ===================================================================
> > --- usb-3.14.orig/drivers/scsi/scsi_error.c
> > +++ usb-3.14/drivers/scsi/scsi_error.c
> > @@ -924,6 +924,7 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd
> > memset(scmd->cmnd, 0, BLK_MAX_CDB);
> > memset(&scmd->sdb, 0, sizeof(scmd->sdb));
> > scmd->request->next_rq = NULL;
> > + scmd->result = 0;
> >
> > if (sense_bytes) {
> > scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
> > Index: usb-3.14/drivers/scsi/scsi_lib.c
> > ===================================================================
> > --- usb-3.14.orig/drivers/scsi/scsi_lib.c
> > +++ usb-3.14/drivers/scsi/scsi_lib.c
> > @@ -159,6 +159,7 @@ static void __scsi_queue_insert(struct s
> > * lock such that the kblockd_schedule_work() call happens
> > * before blk_cleanup_queue() finishes.
> > */
> > + cmd->result = 0;
> > spin_lock_irqsave(q->queue_lock, flags);
> > blk_requeue_request(q, cmd->request);
> > kblockd_schedule_work(q, &device->requeue_work);
> >
> >
> > Maybe only the second one is necessary, but it seemed best to be
> > consistent.
>
> Thanks, I'll add this one to the list as well and see if we can get it
> into the merge window. I take it you'd like a cc to stable on these
> three?
Yes, please.
Alan Stern
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