On Mon, 17 Jun 2019, Finn Thain wrote:
> On Mon, 17 Jun 2019, Ming Lei wrote:
>
> > 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.
> >
> > Finn added the change to replace SCp.buffers_residual with sg_is_last()
> > for fixing updating it, and the similar change has been applied on
> > NCR5380.c
> >
> > Cc: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
>
> Reviewed-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
>
I have to retract that. I think this patch is still wrong.
GETSTCNT() appears to be the number of bytes sent since datao_init() and
not the number of bytes sent since the start of the command. (Note the
CLRSTCNT in datao_init() which appears to clear the transfer counter.) I
don't see how the existing datao_end() could work otherwise. (Juergen?)
So here's another attempt. Ming, I'd be happy to take the blame/credit (in
the form of a From tag etc.) in case you don't want to spend more time on
this.
diff --git a/drivers/scsi/aha152x.c b/drivers/scsi/aha152x.c
index 97872838b983..f07f3fa9b58d 100644
--- a/drivers/scsi/aha152x.c
+++ b/drivers/scsi/aha152x.c
@@ -948,7 +948,6 @@ static int aha152x_internal_queue(struct scsi_cmnd *SCpnt,
SCp.ptr : buffer pointer
SCp.this_residual : buffer length
SCp.buffer : next buffer
- SCp.buffers_residual : left buffers in list
SCp.phase : current state of the command */
if ((phase & resetting) || !scsi_sglist(SCpnt)) {
@@ -956,13 +955,11 @@ static int aha152x_internal_queue(struct scsi_cmnd *SCpnt,
SCpnt->SCp.this_residual = 0;
scsi_set_resid(SCpnt, 0);
SCpnt->SCp.buffer = NULL;
- SCpnt->SCp.buffers_residual = 0;
} else {
scsi_set_resid(SCpnt, scsi_bufflen(SCpnt));
SCpnt->SCp.buffer = scsi_sglist(SCpnt);
SCpnt->SCp.ptr = SG_ADDRESS(SCpnt->SCp.buffer);
SCpnt->SCp.this_residual = SCpnt->SCp.buffer->length;
- SCpnt->SCp.buffers_residual = scsi_sg_count(SCpnt) - 1;
}
DO_LOCK(flags);
@@ -2030,10 +2027,9 @@ static void datai_run(struct Scsi_Host *shpnt)
}
if (CURRENT_SC->SCp.this_residual == 0 &&
- CURRENT_SC->SCp.buffers_residual > 0) {
+ !sg_is_last(CURRENT_SC->SCp.buffer)) {
/* 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;
}
@@ -2136,10 +2132,10 @@ static void datao_run(struct Scsi_Host *shpnt)
CMD_INC_RESID(CURRENT_SC, -2 * data_count);
}
- if(CURRENT_SC->SCp.this_residual==0 && CURRENT_SC->SCp.buffers_residual>0) {
+ if (CURRENT_SC->SCp.this_residual == 0 &&
+ !sg_is_last(CURRENT_SC->SCp.buffer)) {
/* 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 +2154,26 @@ 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();
+ u32 datao_cnt = GETSTCNT();
+ int datao_out = DATA_LEN - scsi_get_resid(CURRENT_SC);
+ int done;
+ struct scatterlist *sg = scsi_sglist(CURRENT_SC);
- CMD_INC_RESID(CURRENT_SC, data_count);
+ CMD_INC_RESID(CURRENT_SC, datao_out - datao_cnt);
- 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;
+ done = scsi_bufflen(CURRENT_SC) - scsi_get_resid(CURRENT_SC);
+ /* Locate the first SG entry not yet sent */
+ while (done > 0 && !sg_is_last(sg)) {
+ if (done < sg->length)
+ break;
+ done -= sg->length;
+ sg = sg_next(sg);
}
- 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.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);
@@ -2501,7 +2501,7 @@ static void get_command(struct seq_file *m, struct scsi_cmnd * ptr)
seq_printf(m, "); resid=%d; residual=%d; buffers=%d; phase |",
scsi_get_resid(ptr), ptr->SCp.this_residual,
- ptr->SCp.buffers_residual);
+ sg_nents(ptr->SCp.buffer) - 1);
if (ptr->SCp.phase & not_issued)
seq_puts(m, "not issued|");
--
