scsi: advansys: use sg helper to iterate over scatterlist

Unlike the legacy I/O path, scsi-mq preallocates a large array to hold
the scatterlist for each request. This static allocation can consume
substantial amounts of memory on modern controllers which support a
large number of concurrently outstanding requests.

To facilitate a switch to a smaller static allocation combined with a
dynamic allocation for requests that need it, we need to make sure all
SCSI drivers handle chained scatterlists correctly.

Convert remaining drivers that directly dereference the scatterlist
array to using the iterator functions.

[mkp: clarified commit message]

Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
index d37584403c334be483283097581c25c799cde78c..b87de8d3d844055bc323f6bc30eb30a3873c2b1a 100644 (file)
--- a/drivers/scsi/advansys.c
+++ b/drivers/scsi/advansys.c
@@ -7714,7 +7714,7 @@ adv_get_sglist(struct asc_board *boardp, adv_req_t *reqp,
                                sg_block->sg_ptr = 0L; /* Last ADV_SG_BLOCK in list. */
                                return ADV_SUCCESS;
                        }
-                       slp++;
+                       slp = sg_next(slp);
                }
                sg_block->sg_cnt = NO_OF_SG_PER_BLOCK;
                prev_sg_block = sg_block;