Hi Ming,
On 6/18/19 3:37 AM, 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.
Cc: Steffen Maier <maier@xxxxxxxxxxxxx>
Cc: Benjamin Block <bblock@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: linux-s390@xxxxxxxxxxxxxxx
Acked-by: Benjamin Block <bblock@xxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/s390/scsi/zfcp_fc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 33eddb02ee30..b018b61bd168 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -620,7 +620,7 @@ static void zfcp_fc_sg_free_table(struct scatterlist *sg, int count)
{
int i;
- for (i = 0; i < count; i++, sg++)
+ for (i = 0; i < count; i++, sg = sg_next(sg))
if (sg)
free_page((unsigned long) sg_virt(sg));
else
@@ -641,7 +641,7 @@ static int zfcp_fc_sg_setup_table(struct scatterlist *sg, int count)
int i;
sg_init_table(sg, count);
- for (i = 0; i < count; i++, sg++) {
+ for (i = 0; i < count; i++, sg = sg_next(sg)) {
addr = (void *) get_zeroed_page(GFP_KERNEL);
if (!addr) {
zfcp_fc_sg_free_table(sg, i);
I'm still catching up with emails that came during my vacation, so I'm not
fully up-to-date on the current state of this and how to bring in potential
fixups on top.
I think, we also have two more (not so obvious) places in the corresponding
response/completion code path, where we might need to introduce the proper
iterator helper:
zfcp_fsf.c:
static int zfcp_fc_eval_gpn_ft(struct zfcp_fc_req *fc_req,
struct zfcp_adapter *adapter, int max_entries)
{
struct scatterlist *sg = &fc_req->sg_rsp;
...
/* first entry is the header */
for (x = 1; x < max_entries && !last; x++) {
...
if (x % (ZFCP_FC_GPN_FT_ENT_PAGE + 1))
...
else
acc = sg_virt(++sg);
^^^^
zfcp_dbf.c:
static u16 zfcp_dbf_san_res_cap_len_if_gpn_ft(char *tag,
struct zfcp_fsf_req *fsf,
u16 len)
{
struct scatterlist *resp_entry = ct_els->resp;
...
/* the basic CT_IU preamble is the same size as one entry in the GPN_FT
* response, allowing us to skip special handling for it - just skip it
*/
for (x = 1; x < max_entries && !last; x++) {
if (x % (ZFCP_FC_GPN_FT_ENT_PAGE + 1))
...
else
acc = sg_virt(++resp_entry);
^^^^^^^^^^^^
What do you think?
--
Mit freundlichen Gruessen / Kind regards
Steffen Maier
Linux on IBM Z Development
https://www.ibm.com/privacy/us/en/
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschaeftsfuehrung: Dirk Wittkopp
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294
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