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 <ming.lei@xxxxxxxxxx>
> 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 <ming.lei@xxxxxxxxxx>
> ---
> 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".
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;
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?
diff --git a/drivers/scsi/aha152x.c b/drivers/scsi/aha152x.c
index 97872838b983..6d0518f616cb 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 +2154,24 @@ 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;
+ struct scatterlist *sg = scsi_sglist(CURRENT_SC);
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;
+ /* 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 +2499,7 @@ 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|");
--
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