Re: [PATCH block#for-2.6.31 2/3] block: set rq->resid_len to blk_rq_bytes()on issue

[Sergei Shtylyov]

Hello.

Tejun Heo wrote:

> > > Index: block/drivers/message/fusion/mptsas.c
> > > ===================================================================
> > > --- block.orig/drivers/message/fusion/mptsas.c
> > > +++ block/drivers/message/fusion/mptsas.c
> > > @@ -1357,7 +1357,8 @@ static int mptsas_smp_handler(struct Scs
> > >          smprep = (SmpPassthroughReply_t *)ioc->sas_mgmt.reply;
> > >          memcpy(req->sense, smprep, sizeof(*smprep));
> > >          req->sense_len = sizeof(*smprep);
> > > -        rsp->resid_len = blk_rq_bytes(rsp) - smprep->ResponseDataLength;
> > > +        req->resid_len = 0;
> > > +        rsp->resid_len -= smprep->ResponseDataLength;
> > >       
> >    Is negative resid_len intended here? If so, shouldn't it be simply:
> >
> >         rsp->resid_len = -smprep->ResponseDataLength;
> >     
>
> From patch description.
>
>  This patchset restores the original behavior by setting rq->resid_len
>  to blk_rq_bytes(rq) on issue and restoring explicit clearing in
>  affected drivers.
>
> So, rsp->resid_len equals the initial request length before the
> subtraction and after subtraction it becomes the residue count.  The
> original code was
>
> 	req->data_len = 0;
> 	rsp->data_len -= smprep->ResponseDataLength;
>   

 Ah, I've confused up 'rsp' and 'req' as being one thing. Nevermind 
then. :-<

> > > Index: block/drivers/scsi/libsas/sas_expander.c
> > > ===================================================================
> > > --- block.orig/drivers/scsi/libsas/sas_expander.c
> > > +++ block/drivers/scsi/libsas/sas_expander.c
> > > @@ -1937,7 +1937,11 @@ int sas_smp_handler(struct Scsi_Host *sh
> > >      if (ret > 0) {
> > >          /* positive number is the untransferred residual */
> > >          rsp->resid_len = ret;
> > > +        req->resid_len = 0;
> > >          ret = 0;
> > > +    } else if (ret == 0) {
> > > +        rsp->resid_len = 0;
> > > +        req->resid_len = 0;
> > >       
>
> Heh... there's a reason I mentioned the original commit.  The original
> code was
>
> 	if (ret > 0) {
> 		/* positive number is the untransferred residual */
> 		rsp->data_len = ret;
> 		req->data_len = 0;
> 		ret = 0;
> 	} else if (ret == 0) {
> 		rsp->data_len = 0;
> 		req->data_len = 0;
> 	}
>   

  But still,

               req->data_len = 0;

is common between both branches, so could be moved after the *if* statement.

> > > Index: block/drivers/scsi/libsas/sas_host_smp.c
> > > ===================================================================
> > > --- block.orig/drivers/scsi/libsas/sas_host_smp.c
> > > +++ block/drivers/scsi/libsas/sas_host_smp.c
> > > @@ -176,9 +176,6 @@ int sas_smp_host_handler(struct Scsi_Hos
> > >      resp_data[1] = req_data[1];
> > >      resp_data[2] = SMP_RESP_FUNC_UNK;
> > >  
> > > -    req->resid_len = blk_rq_bytes(req);
> > > -    rsp->resid_len = blk_rq_bytes(rsp);
> > > -
> > >       
>
> Cuz it's already set to blk_rq_bytes().
>   

  Mixed them up again... :-<

> > >      switch (req_data[1]) {
> > >      case SMP_REPORT_GENERAL:
> > >          req->resid_len -= 8;
> > > Index: block/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > > ===================================================================
> > > --- block.orig/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > > +++ block/drivers/scsi/mpt2sas/mpt2sas_transport.c
> > > @@ -1170,8 +1170,8 @@ transport_smp_handler(struct Scsi_Host *
> > >  
> > >          memcpy(req->sense, mpi_reply, sizeof(*mpi_reply));
> > >          req->sense_len = sizeof(*mpi_reply);
> > > -        rsp->resid_len = blk_rq_bytes(rsp) -
> > > -                 mpi_reply->ResponseDataLength;
> > > +        req->resid_len = 0;
> > > +        rsp->resid_len -= mpi_reply->ResponseDataLength;
> > >       
> >    Again, is negative resid_len intended?
> >     
>
> Ditto.
>   

  ... and again.

> Thanks.
>   

WBR, Sergei


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