diff mbox series

[V4,05/16] scsi: ipr: use sg helper to operate scatterlist

Message ID 20190617030349.26415-6-ming.lei@redhat.com (mailing list archive)
State Superseded
Headers show
Series use sg helper to operate scatterlist | expand

Commit Message

Ming Lei June 17, 2019, 3:03 a.m. UTC 
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@redhat.com>
---
 drivers/scsi/ipr.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

Comments

Christoph Hellwig June 17, 2019, 8:24 a.m. UTC | #1 
> -	for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) {
> -		struct page *page = sg_page(&scatterlist[i]);
> +	for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), buffer += bsize_elem) {

Please split the overly long line.

> +		struct page *page = sg_page(sg);
>  
>  		kaddr = kmap(page);
>  		memcpy(kaddr, buffer, bsize_elem);
>  		kunmap(page);

Not new in this patch, but this is buggy as scatterlists could have
offsets.  This should probably use the scatterlist.c copy helper
eventually.
Ming Lei June 17, 2019, 8:50 a.m. UTC | #2 
On Mon, Jun 17, 2019 at 10:24:23AM +0200, Christoph Hellwig wrote:
> > -	for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) {
> > -		struct page *page = sg_page(&scatterlist[i]);
> > +	for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), buffer += bsize_elem) {
> 
> Please split the overly long line.

Fine.

> 
> > +		struct page *page = sg_page(sg);
> >  
> >  		kaddr = kmap(page);
> >  		memcpy(kaddr, buffer, bsize_elem);
> >  		kunmap(page);
> 
> Not new in this patch, but this is buggy as scatterlists could have
> offsets.  This should probably use the scatterlist.c copy helper
> eventually.

This sglist is allocated by driver, see ipr_copy_ucode_buffer(), so
offset for any element is zero.

Thanks,
Ming
diff mbox series

Patch

diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 6d053e220153..383603973937 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -3915,22 +3915,22 @@  static int ipr_copy_ucode_buffer(struct ipr_sglist *sglist,
 				 u8 *buffer, u32 len)
 {
 	int bsize_elem, i, result = 0;
-	struct scatterlist *scatterlist;
+	struct scatterlist *sg;
 	void *kaddr;
 
 	/* Determine the actual number of bytes per element */
 	bsize_elem = PAGE_SIZE * (1 << sglist->order);
 
-	scatterlist = sglist->scatterlist;
+	sg = sglist->scatterlist;
 
-	for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) {
-		struct page *page = sg_page(&scatterlist[i]);
+	for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), buffer += bsize_elem) {
+		struct page *page = sg_page(sg);
 
 		kaddr = kmap(page);
 		memcpy(kaddr, buffer, bsize_elem);
 		kunmap(page);
 
-		scatterlist[i].length = bsize_elem;
+		sg->length = bsize_elem;
 
 		if (result != 0) {
 			ipr_trace;
@@ -3939,13 +3939,13 @@  static int ipr_copy_ucode_buffer(struct ipr_sglist *sglist,
 	}
 
 	if (len % bsize_elem) {
-		struct page *page = sg_page(&scatterlist[i]);
+		struct page *page = sg_page(sg);
 
 		kaddr = kmap(page);
 		memcpy(kaddr, buffer, len % bsize_elem);
 		kunmap(page);
 
-		scatterlist[i].length = len % bsize_elem;
+		sg->length = len % bsize_elem;
 	}
 
 	sglist->buffer_len = len;
@@ -3966,6 +3966,7 @@  static void ipr_build_ucode_ioadl64(struct ipr_cmnd *ipr_cmd,
 	struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb;
 	struct ipr_ioadl64_desc *ioadl64 = ipr_cmd->i.ioadl64;
 	struct scatterlist *scatterlist = sglist->scatterlist;
+	struct scatterlist *sg;
 	int i;
 
 	ipr_cmd->dma_use_sg = sglist->num_dma_sg;
@@ -3974,10 +3975,10 @@  static void ipr_build_ucode_ioadl64(struct ipr_cmnd *ipr_cmd,
 
 	ioarcb->ioadl_len =
 		cpu_to_be32(sizeof(struct ipr_ioadl64_desc) * ipr_cmd->dma_use_sg);
-	for (i = 0; i < ipr_cmd->dma_use_sg; i++) {
+	for_each_sg(scatterlist, sg, ipr_cmd->dma_use_sg, i) {
 		ioadl64[i].flags = cpu_to_be32(IPR_IOADL_FLAGS_WRITE);
-		ioadl64[i].data_len = cpu_to_be32(sg_dma_len(&scatterlist[i]));
-		ioadl64[i].address = cpu_to_be64(sg_dma_address(&scatterlist[i]));
+		ioadl64[i].data_len = cpu_to_be32(sg_dma_len(sg));
+		ioadl64[i].address = cpu_to_be64(sg_dma_address(sg));
 	}
 
 	ioadl64[i-1].flags |= cpu_to_be32(IPR_IOADL_FLAGS_LAST);
@@ -3997,6 +3998,7 @@  static void ipr_build_ucode_ioadl(struct ipr_cmnd *ipr_cmd,
 	struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb;
 	struct ipr_ioadl_desc *ioadl = ipr_cmd->i.ioadl;
 	struct scatterlist *scatterlist = sglist->scatterlist;
+	struct scatterlist *sg;
 	int i;
 
 	ipr_cmd->dma_use_sg = sglist->num_dma_sg;
@@ -4006,11 +4008,11 @@  static void ipr_build_ucode_ioadl(struct ipr_cmnd *ipr_cmd,
 	ioarcb->ioadl_len =
 		cpu_to_be32(sizeof(struct ipr_ioadl_desc) * ipr_cmd->dma_use_sg);
 
-	for (i = 0; i < ipr_cmd->dma_use_sg; i++) {
+	for_each_sg(scatterlist, sg, ipr_cmd->dma_use_sg, i) {
 		ioadl[i].flags_and_data_len =
-			cpu_to_be32(IPR_IOADL_FLAGS_WRITE | sg_dma_len(&scatterlist[i]));
+			cpu_to_be32(IPR_IOADL_FLAGS_WRITE | sg_dma_len(sg));
 		ioadl[i].address =
-			cpu_to_be32(sg_dma_address(&scatterlist[i]));
+			cpu_to_be32(sg_dma_address(sg));
 	}
 
 	ioadl[i-1].flags_and_data_len |=