Re: [Qemu-devel] Re: [PATCH] scsi-generic: bugfixes for 'SCSIRequest' conversion

[Nicholas A. Bellinger]

On Tue, 2010-12-21 at 12:49 +1100, Benjamin Herrenschmidt wrote:
> > Yep, so it appears that commit 89c0f6438d16 did introduce the bogus
> > 'double complete' in scsi_read_complete, which I think was intended to
> > handle residual counts for TYPE_TYPE...
> > 
> >  /* Cancel a pending data transfer.  */
> > @@ -251,6 +257,8 @@ static void scsi_read_complete(void * opaque, int ret)
> > 
> >      r->len = -1;
> >      s->completion(s->opaque, SCSI_REASON_DATA, r->tag, len);
> > +    if (len == 0)
> > +        scsi_command_complete(r, 0);
> >  }
> > 
> > I am currently under the assumption for this and bsg_read_complete that
> > s->completion(..., len) is handling the residual count back to block.
> > 
> > Is this correct..?
> 
> So I just debugged a crash where loading my vscsi driver kills qemu
> (segfault) after trying to complete a command twice with scsi-generic.
> 
> Removing the above hunk fixes it. So this is a genuine fix that should
> be applied (asap even :-)
> 

Hi Ben,

Thanks for verifying this one.  Kevin, please make sure this original
patch to drop the bogus double complete gets picked up.

Best Regards,

--nab

> I still have an odd problem with scsi-disk.c where reading from an
> empty cdrom drive crashes it, I'll debug that later.
> 
> Cheers,
> Ben.
> 
>