On Fri, Jun 14, 2019 at 08:36:38PM +1000, Finn Thain wrote:
> On Fri, 14 Jun 2019, Ming Lei wrote:
>
> >
> > Follows the fixed version, could you review again?
> >
> > From f03484d4bac083c39d70665cfbadb641093b63de Mon Sep 17 00:00:00 2001
> > From: Ming Lei <[email protected]>
> > Date: Wed, 12 Jun 2019 20:37:35 +0800
> > Subject: [PATCH] scsi: aha152x: use sg helper to operate scatterlist
> >
> > Use the scatterlist iterators and remove direct indexing of the
> > scatterlist array.
> >
> > This way allows us to pre-allocate one small scatterlist, which can be
> > chained with one runtime allocated scatterlist if the pre-allocated one
> > isn't enough for the whole request.
> >
> > Signed-off-by: Ming Lei <[email protected]>
> > ---
> > drivers/scsi/aha152x.c | 34 ++++++++++++++++++++--------------
> > 1 file changed, 20 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/scsi/aha152x.c b/drivers/scsi/aha152x.c
> > index 97872838b983..7faecdefda56 100644
> > --- a/drivers/scsi/aha152x.c
> > +++ b/drivers/scsi/aha152x.c
> > @@ -2033,7 +2033,7 @@ static void datai_run(struct Scsi_Host *shpnt)
> > CURRENT_SC->SCp.buffers_residual > 0) {
> > /* advance to next buffer */
> > CURRENT_SC->SCp.buffers_residual--;
> > - CURRENT_SC->SCp.buffer++;
> > + CURRENT_SC->SCp.buffer =
> > sg_next(CURRENT_SC->SCp.buffer);
> > CURRENT_SC->SCp.ptr =
> > SG_ADDRESS(CURRENT_SC->SCp.buffer);
> > CURRENT_SC->SCp.this_residual =
> > CURRENT_SC->SCp.buffer->length;
> > }
> > @@ -2139,7 +2139,7 @@ static void datao_run(struct Scsi_Host *shpnt)
> > if(CURRENT_SC->SCp.this_residual==0 &&
> > CURRENT_SC->SCp.buffers_residual>0) {
> > /* advance to next buffer */
> > CURRENT_SC->SCp.buffers_residual--;
> > - CURRENT_SC->SCp.buffer++;
> > + CURRENT_SC->SCp.buffer =
> > sg_next(CURRENT_SC->SCp.buffer);
> > CURRENT_SC->SCp.ptr =
> > SG_ADDRESS(CURRENT_SC->SCp.buffer);
> > CURRENT_SC->SCp.this_residual =
> > CURRENT_SC->SCp.buffer->length;
> > }
> > @@ -2158,22 +2158,28 @@ static void datao_run(struct Scsi_Host *shpnt)
> > static void datao_end(struct Scsi_Host *shpnt)
> > {
> > if(TESTLO(DMASTAT, DFIFOEMP)) {
> > - int data_count = (DATA_LEN - scsi_get_resid(CURRENT_SC)) -
> > - GETSTCNT();
> > + int done = GETSTCNT();
> > + int data_count = (DATA_LEN - scsi_get_resid(CURRENT_SC)) - done;
>
> I think that's better than my suggestion.
>
> > + struct scatterlist *sg = scsi_sglist(CURRENT_SC);
> > + int i;
> >
> > CMD_INC_RESID(CURRENT_SC, data_count);
> >
> > - data_count -= CURRENT_SC->SCp.ptr -
> > - SG_ADDRESS(CURRENT_SC->SCp.buffer);
> > - while(data_count>0) {
> > - CURRENT_SC->SCp.buffer--;
> > - CURRENT_SC->SCp.buffers_residual++;
> > - data_count -= CURRENT_SC->SCp.buffer->length;
> > + /*
> > + * rewind where we have done, and we have to start from
> > + * the beginning
> > + */
>
> How about, "Locate the first SG entry not yet sent".
OK.
>
> We could use sg_nents_for_len() but it returns a count of sg entries not a
> scatterlist pointer so it's not very helpful here.
>
> > + for (i = 0; done > 0 && !sg_is_last(sg); i++, sg = sg_next(sg))
> > {
> > + if (done < sg->length)
> > + break;
> > + done -= sg->length;
> > }
> > - CURRENT_SC->SCp.ptr = SG_ADDRESS(CURRENT_SC->SCp.buffer) -
> > - data_count;
> > - CURRENT_SC->SCp.this_residual = CURRENT_SC->SCp.buffer->length +
> > - data_count;
> > +
> > + CURRENT_SC->SCp.buffers_residual = i;
>
> Contradicting my previous email, that's still not right. I think it would
> have to be,
>
> CURRENT_SC->SCp.buffers_residual = scsi_sg_count(CURRENT_SC) -
> i;
Right, my fault.
>
> But we could remove all references to SCp.buffers_residual, like I did in
> patch 15/15 for NCR5380.c.
>
> > + CURRENT_SC->SCp.buffer = sg;
> > + CURRENT_SC->SCp.ptr = SG_ADDRESS(CURRENT_SC->SCp.buffer) + done;
> > + CURRENT_SC->SCp.this_residual = CURRENT_SC->SCp.buffer->length -
> > + done;
> > }
> >
> > SETPORT(SXFRCTL0, CH1|CLRCH1|CLRSTCNT);
> >
>
> What do you think of the revised patch below?
Looks fine, I will include it in V4.
Thanks,
Ming
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