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From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-scsi@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>, Jim Gill <jgill@vmware.com>,
	Cathy Avery <cavery@redhat.com>,
	"Ewan D . Milne" <emilne@redhat.com>,
	Brian King <brking@us.ibm.com>,
	James Smart <james.smart@broadcom.com>,
	"Juergen E . Fischer" <fischer@norbit.de>,
	Michael Schmitz <schmitzmic@gmail.com>,
	Finn Thain <fthain@telegraphics.com.au>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	devel@driverdev.osuosl.org, linux-usb@vger.kernel.org,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Benjamin Block <bblock@linux.ibm.com>,
	Kim Bradley <kim.jamie.bradley@gmail.com>
Subject: Re: [PATCH V4 09/16] staging: rtsx: use sg helper to operate scatterlist
Date: Mon, 17 Jun 2019 17:15:26 +0800
Message-ID: <20190617091524.GB31002@ming.t460p> (raw)
In-Reply-To: <20190617082706.GI7455@lst.de>

On Mon, Jun 17, 2019 at 10:27:06AM +0200, Christoph Hellwig wrote:
> On Mon, Jun 17, 2019 at 11:03:42AM +0800, 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.
> 
> The scatterlist handling here looks completely bogus, it really
> needs to stop using the index and switch to proper sg_next-based
> iteration.

Yeah, I agree, looks we may convert in the following way by
storing current 'sg', and the 'offset' already stores the actual offset
on the current 'sg'.

diff --git a/drivers/staging/rts5208/rtsx_transport.c b/drivers/staging/rts5208/rtsx_transport.c
index 8277d7895608..861b4cc4562e 100644
--- a/drivers/staging/rts5208/rtsx_transport.c
+++ b/drivers/staging/rts5208/rtsx_transport.c
@@ -32,7 +32,7 @@
 unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
 				       unsigned int buflen,
 				       struct scsi_cmnd *srb,
-				       unsigned int *index,
+				       struct scatterlist **cur_sg,
 				       unsigned int *offset,
 				       enum xfer_buf_dir dir)
 {
@@ -60,18 +60,18 @@ unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
 	 * each page has to be kmap()'ed separately.
 	 */
 	} else {
-		struct scatterlist *sg =
-				(struct scatterlist *)scsi_sglist(srb)
-				+ *index;
+		struct scatterlist *sg = *cur_sg ?:
+				(struct scatterlist *)scsi_sglist(srb);
+
 
 		/*
 		 * This loop handles a single s-g list entry, which may
 		 * include multiple pages.  Find the initial page structure
 		 * and the starting offset within the page, and update
-		 * the *offset and *index values for the next loop.
+		 * the *offset values for the next loop.
 		 */
 		cnt = 0;
-		while (cnt < buflen && *index < scsi_sg_count(srb)) {
+		while (cnt < buflen && sg) {
 			struct page *page = sg_page(sg) +
 					((sg->offset + *offset) >> PAGE_SHIFT);
 			unsigned int poff = (sg->offset + *offset) &
@@ -85,8 +85,7 @@ unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
 			} else {
 				/* Transfer continues to next s-g entry */
 				*offset = 0;
-				++*index;
-				++sg;
+				sg = sg_next(sg);
 			}
 
 			while (sglen > 0) {
@@ -120,9 +119,10 @@ unsigned int rtsx_stor_access_xfer_buf(unsigned char *buffer,
 void rtsx_stor_set_xfer_buf(unsigned char *buffer,
 			    unsigned int buflen, struct scsi_cmnd *srb)
 {
-	unsigned int index = 0, offset = 0;
+	unsigned int offset = 0;
+	struct scatterlist *sg = NULL;
 
-	rtsx_stor_access_xfer_buf(buffer, buflen, srb, &index, &offset,
+	rtsx_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
 				  TO_XFER_BUF);
 	if (buflen < scsi_bufflen(srb))
 		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
@@ -131,9 +131,10 @@ void rtsx_stor_set_xfer_buf(unsigned char *buffer,
 void rtsx_stor_get_xfer_buf(unsigned char *buffer,
 			    unsigned int buflen, struct scsi_cmnd *srb)
 {
-	unsigned int index = 0, offset = 0;
+	unsigned int offset = 0;
+	struct scatterlist *sg = NULL;
 
-	rtsx_stor_access_xfer_buf(buffer, buflen, srb, &index, &offset,
+	rtsx_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
 				  FROM_XFER_BUF);
 	if (buflen < scsi_bufflen(srb))
 		scsi_set_resid(srb, scsi_bufflen(srb) - buflen);
diff --git a/drivers/staging/rts5208/spi.c b/drivers/staging/rts5208/spi.c
index f1e9e80044ed..6ad4278de531 100644
--- a/drivers/staging/rts5208/spi.c
+++ b/drivers/staging/rts5208/spi.c
@@ -554,7 +554,8 @@ int spi_read_flash_id(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 int spi_read_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 {
 	int retval;
-	unsigned int index = 0, offset = 0;
+	unsigned int offset = 0;
+	struct scatterlist *sg = NULL;
 	u8 ins, slow_read;
 	u32 addr;
 	u16 len;
@@ -631,7 +632,7 @@ int spi_read_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 			return STATUS_FAIL;
 		}
 
-		rtsx_stor_access_xfer_buf(buf, pagelen, srb, &index, &offset,
+		rtsx_stor_access_xfer_buf(buf, pagelen, srb, &sg, &offset,
 					  TO_XFER_BUF);
 
 		addr += pagelen;
@@ -651,7 +652,8 @@ int spi_write_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 	u32 addr;
 	u16 len;
 	u8 *buf;
-	unsigned int index = 0, offset = 0;
+	unsigned int offset = 0;
+	struct scatterlist *sg = NULL;
 
 	spi_set_err_code(chip, SPI_NO_ERR);
 
@@ -679,7 +681,7 @@ int spi_write_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 				return STATUS_FAIL;
 			}
 
-			rtsx_stor_access_xfer_buf(buf, 1, srb, &index, &offset,
+			rtsx_stor_access_xfer_buf(buf, 1, srb, &sg, &offset,
 						  FROM_XFER_BUF);
 
 			rtsx_init_cmd(chip);
@@ -722,7 +724,7 @@ int spi_write_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 			return STATUS_ERROR;
 
 		while (len) {
-			rtsx_stor_access_xfer_buf(buf, 1, srb, &index, &offset,
+			rtsx_stor_access_xfer_buf(buf, 1, srb, &sg, &offset,
 						  FROM_XFER_BUF);
 
 			rtsx_init_cmd(chip);
@@ -788,7 +790,7 @@ int spi_write_flash(struct scsi_cmnd *srb, struct rtsx_chip *chip)
 
 			rtsx_send_cmd_no_wait(chip);
 
-			rtsx_stor_access_xfer_buf(buf, pagelen, srb, &index,
+			rtsx_stor_access_xfer_buf(buf, pagelen, srb, &sg,
 						  &offset, FROM_XFER_BUF);
 
 			retval = rtsx_transfer_data(chip, 0, buf, pagelen, 0,

Thanks,
Ming

  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-17  3:03 [PATCH V4 00/16] " Ming Lei
2019-06-17  3:03 ` [PATCH V4 01/16] scsi: vmw_pscsi: " Ming Lei
2019-06-17  8:22   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 02/16] scsi: advansys: " Ming Lei
2019-06-17  8:22   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 03/16] scsi: lpfc: " Ming Lei
2019-06-17  8:22   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 04/16] scsi: mvumi: " Ming Lei
2019-06-17  8:22   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 05/16] scsi: ipr: " Ming Lei
2019-06-17  8:24   ` Christoph Hellwig
2019-06-17  8:50     ` Ming Lei
2019-06-17  3:03 ` [PATCH V4 06/16] scsi: pmcraid: " Ming Lei
2019-06-17  8:24   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 07/16] usb: image: microtek: " Ming Lei
2019-06-17  8:25   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 08/16] staging: unisys: visorhba: " Ming Lei
2019-06-17  8:25   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 09/16] staging: rtsx: " Ming Lei
2019-06-17  8:27   ` Christoph Hellwig
2019-06-17  9:15     ` Ming Lei [this message]
2019-06-17  9:24       ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 10/16] s390: zfcp_fc: " Ming Lei
2019-06-17  8:27   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 11/16] scsi: aha152x: " Ming Lei
2019-06-17  3:35   ` Finn Thain
2019-06-17 23:35     ` Finn Thain
2019-06-18  0:15       ` Ming Lei
2019-06-17  8:28   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 12/16] scsi: imm: " Ming Lei
2019-06-17  8:28   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 13/16] scsi: pcmcia: nsp_cs: " Ming Lei
2019-06-17  8:29   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 14/16] scsi: ppa: " Ming Lei
2019-06-17  8:29   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 15/16] scsi: wd33c93: " Ming Lei
2019-06-17  8:29   ` Christoph Hellwig
2019-06-17  3:03 ` [PATCH V4 16/16] NCR5380: Support chained sg lists Ming Lei
2019-06-17  8:30   ` Christoph Hellwig
2019-06-17 23:52 ` [PATCH V4 00/16] use sg helper to operate scatterlist Bart Van Assche

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