[OpenFCoE PATCH] [PATCH] Performance improvement, combine received data copy with CRC.

[Joe Eykholt <fcoe@eykholt.com>]

[PATCH] Performance improvement, combine received data copy with CRC.



Signed-off-by: Joe Eykholt <fcoe@eykholt.com>

---
 drivers/scsi/ofc/openfc/openfc_scsi.c |  130 +++++++++++++++++++++++----------
 1 files changed, 90 insertions(+), 40 deletions(-)

diff --git a/drivers/scsi/ofc/openfc/openfc_scsi.c b/drivers/scsi/ofc/openfc/openfc_scsi.c
index 5fa0ad6..b5fc393 100644
--- a/drivers/scsi/ofc/openfc/openfc_scsi.c
+++ b/drivers/scsi/ofc/openfc/openfc_scsi.c
@@ -62,7 +62,6 @@ static void openfc_tm_done(struct fc_seq *, struct fc_frame *, void *);
 static void openfc_scsi_error(enum fc_event, void *);
 static int openfc_abort_internal(struct fcdev *, struct fc_scsi_pkt *,
 				 struct fc_frame *);
-int openfc_cp_to_user(struct fc_scsi_pkt *, uint, void *, int);
 void openfc_scsi_cleanup(struct fc_scsi_pkt *);
 static void openfc_timeout_error(struct fc_scsi_pkt *);
 void openfc_scsi_rec_rcv(struct fc_seq *, struct fc_frame *, void *);
@@ -102,9 +101,13 @@ static void openfc_scsi_recv_data(struct fc_scsi_pkt *fsp, struct fc_frame *fp)
 	struct fcoe_dev_stats *sp;
 	struct fc_frame_header *fh;
 	size_t offset;
+	u32 crc;
+	u32 copy_len = 0;
 	size_t len;
 	void *buf;
 
+	if (!sc->request_buffer)
+		return;			/* XXX possible? */
 	fh = fc_frame_header_get(fp);
 	offset = net32_get(&fh->fh_parm_offset);
 	len = fp->fr_len - sizeof(*fh);
@@ -115,13 +118,8 @@ static void openfc_scsi_recv_data(struct fc_scsi_pkt *fsp, struct fc_frame *fp)
 		 * this should never happen
 		 */
 		if ((fp->fr_flags & FCPHF_CRC_UNCHECKED) &&
-		    fc_frame_crc_check(fp)) {
-			sp = openfcp->fd.dev_stats[smp_processor_id()];
-			sp->ErrorFrames++;
-			if (sp->InvalidCRCCount++ < 5)
-				SA_LOG("CRC error on data frame");
-			return;	/* just ignore the frame */
-		}
+		    fc_frame_crc_check(fp))
+			goto crc_err;
 		if (openfc_debug) {
 			SA_LOG("data received past end.	 "
 			       "len %zx offset %zx "
@@ -130,42 +128,95 @@ static void openfc_scsi_recv_data(struct fc_scsi_pkt *fsp, struct fc_frame *fp)
 		openfc_scsi_retry(fsp);
 		return;
 	}
-
-	/*
-	 * Eventually, do scatter/gather buffer system to avoid
-	 * this copy.  A NULL buffer means we discard the data.
-	 */
+	crc = 0;
 	if (sc->use_sg) {
-		len = openfc_cp_to_user(fsp, offset, buf, len);
-		ASSERT_NOTIMPL(len > 0);
-	} else if (sc->request_buffer != NULL) {
-		__memcpy((void *)sc->request_buffer + offset, buf, len);
-	}
+		struct scatterlist *sg;
+		struct scatterlist *sg_limit;
+		size_t remaining, sg_bytes;
+		size_t off;
+		void *page_addr;
 
-	/*
-	 * If the lower layer didn't do the CRC check, do it here.
-	 * This is the only type of frame the transport might not check.
-	 * Eventually we could do the CRC calculation during the copy above.
-	 */
-	if ((fp->fr_flags & FCPHF_CRC_UNCHECKED) && fc_frame_crc_check(fp)) {
-		sp = openfcp->fd.dev_stats[smp_processor_id()];
-		sp->ErrorFrames++;
-		if (sp->InvalidCRCCount++ < 5)
-			SA_LOG("CRC error on data frame");
+		if (fp->fr_flags & FCPHF_CRC_UNCHECKED)
+			crc = crc32_sb8_64_bit(~0, (u8 *) fh, sizeof(*fh));
 
-		/*
-		 * Assume the frame is total garbage.
-		 * We may have copied it over the good part of the buffer.
-		 * If so, we need to retry the entire operation.
-		 * Otherwise, ignore it.
-		 */
-		if (offset < fsp->xfer_len)
-			openfc_scsi_retry(fsp);
-		return;
-	}
+		sg = (struct scatterlist *)sc->request_buffer;
+		sg_limit = sg + sc->use_sg;
+		remaining = len;
 
-	fsp->xfer_len += len;
+		while (remaining > 0 && sg < sg_limit) {
+			if (offset >= sg->length) {
+				offset -= sg->length;
+				sg++;
+				continue;
+			}
+			sg_bytes = min(remaining, sg->length - offset);
 
+			/*
+			 * The scatterlist item may be bigger than PAGE_SIZE,
+			 * but we are limited to mapping PAGE_SIZE at a time.
+			 */
+			off = offset + sg->offset;
+			sg_bytes = min(sg_bytes,
+				       (PAGE_SIZE - (off & ~PAGE_MASK)));
+			page_addr = kmap_atomic(sg_page(sg) +
+						(off >> PAGE_SHIFT),
+						KM_SOFTIRQ0);
+			if (!page_addr)
+				break;		/* XXX panic? */
+
+			if (fsp->state != OPENFC_SRB_ABORT_PENDING) {
+				if (fp->fr_flags & FCPHF_CRC_UNCHECKED) {
+					crc = crc32_copy(crc,
+							 (char *)page_addr +
+							 (off & ~PAGE_MASK),
+							 buf, sg_bytes);
+				} else {
+					__memcpy((char *)page_addr +
+						 (off & ~PAGE_MASK),
+						 buf, sg_bytes);
+				}
+			}
+			kunmap_atomic(page_addr, KM_SOFTIRQ0);
+			buf += sg_bytes;
+			offset += sg_bytes;
+			remaining -= sg_bytes;
+			copy_len += sg_bytes;
+		}
+		if (fp->fr_flags & FCPHF_CRC_UNCHECKED)
+			goto crc_check;
+	} else if (fp->fr_flags & FCPHF_CRC_UNCHECKED) {
+		crc = crc32_sb8_64_bit(~0, (u8 *)fh, sizeof(*fh));
+		crc = crc32_copy(crc, (void *)sc->request_buffer + offset,
+				 buf, len);
+		copy_len = len;
+crc_check:
+		buf = fc_frame_payload_get(fp, 0);
+		if (len % 4) {
+			crc = crc32_sb8_64_bit(crc, buf + len, 4 - (len % 4));
+			len += 4 - (len % 4);
+		}
+		if (~crc != le32_to_cpu(*(__le32 *)(buf + len))) {
+crc_err:
+			sp = openfcp->fd.dev_stats[smp_processor_id()];
+			sp->ErrorFrames++;
+			if (sp->InvalidCRCCount++ < 5)
+				SA_LOG("CRC error on data frame");
+			/*
+			 * Assume the frame is total garbage.
+			 * We may have copied it over the good part
+			 * of the buffer.
+			 * If so, we need to retry the entire operation.
+			 * Otherwise, ignore it.
+			 */
+			if (offset < fsp->xfer_len)
+				openfc_scsi_retry(fsp);
+			return;
+		}
+	} else {
+		__memcpy((void *)sc->request_buffer + offset, buf, len);
+		copy_len = len;
+	}
+	fsp->xfer_len += copy_len;
 	if (fsp->xfer_len == fsp->data_len)
 		fsp->state = OPENFC_SRB_WAIT_FOR_STATUS;
 }
@@ -317,7 +368,6 @@ static void openfc_scsi_send_data(struct fc_scsi_pkt *fsp, struct fc_seq *sp,
 
 	if (fsp->xfer_len == fsp->data_len)
 		fsp->state = OPENFC_SRB_WAIT_FOR_STATUS;
-	return;
 }
 
 /*