[SCSI] libiscsi_tcp: support padding offload

cxgb3i does not offload the processing of the header,
but it will always process the padding. This patch
adds a padding offload flag to detect when the LLD
supports this.

The patch also modifies the header processing so that
we do not try to read/bypass the header dugest in the
skb. cxgb3i will not include it with the header like
with other offload cards.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

4 files changed, 29 insertions, 22 deletions

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index de5c9b3e51fb..23808dfe22ba 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -194,7 +194,7 @@ iscsi_sw_tcp_conn_restore_callbacks(struct iscsi_sw_tcp_conn *tcp_sw_conn)
 
 /**
  * iscsi_sw_tcp_xmit_segment - transmit segment
- * @tcp_sw_conn: the iSCSI TCP connection
+ * @tcp_conn: the iSCSI TCP connection
  * @segment: the buffer to transmnit
  *
  * This function transmits as much of the buffer as
@@ -205,14 +205,15 @@ iscsi_sw_tcp_conn_restore_callbacks(struct iscsi_sw_tcp_conn *tcp_sw_conn)
  * hash as it goes. When the entire segment has been transmitted,
  * it will retrieve the hash value and send it as well.
  */
-static int iscsi_sw_tcp_xmit_segment(struct iscsi_sw_tcp_conn *tcp_sw_conn,
+static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
                                      struct iscsi_segment *segment)
 {
+        struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
         struct socket *sk = tcp_sw_conn->sock;
         unsigned int copied = 0;
         int r = 0;
 
-        while (!iscsi_tcp_segment_done(segment, 0, r)) {
+        while (!iscsi_tcp_segment_done(tcp_conn, segment, 0, r)) {
                 struct scatterlist *sg;
                 unsigned int offset, copy;
                 int flags = 0;
@@ -263,7 +264,7 @@ static int iscsi_sw_tcp_xmit(struct iscsi_conn *conn)
         int rc = 0;
 
         while (1) {
-                rc = iscsi_sw_tcp_xmit_segment(tcp_sw_conn, segment);
+                rc = iscsi_sw_tcp_xmit_segment(tcp_conn, segment);
                 if (rc < 0) {
                         rc = ISCSI_ERR_XMIT_FAILED;
                         goto error;
diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index 9df6b3436e4a..a745f91d2928 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -159,6 +159,7 @@ iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
 
 /**
  * iscsi_tcp_segment_done - check whether the segment is complete
+ * @tcp_conn: iscsi tcp connection
  * @segment: iscsi segment to check
  * @recv: set to one of this is called from the recv path
  * @copied: number of bytes copied
@@ -172,7 +173,8 @@ iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
  *
  * This function must be re-entrant.
  */
-int iscsi_tcp_segment_done(struct iscsi_segment *segment, int recv,
+int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
+                           struct iscsi_segment *segment, int recv,
                            unsigned copied)
 {
         static unsigned char padbuf[ISCSI_PAD_LEN];
@@ -225,13 +227,15 @@ int iscsi_tcp_segment_done(struct iscsi_segment *segment, int recv,
         }
 
         /* Do we need to handle padding? */
-        pad = iscsi_padding(segment->total_copied);
-        if (pad != 0) {
-                debug_tcp("consume %d pad bytes\n", pad);
-                segment->total_size += pad;
-                segment->size = pad;
-                segment->data = padbuf;
-                return 0;
+        if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
+                pad = iscsi_padding(segment->total_copied);
+                if (pad != 0) {
+                        debug_tcp("consume %d pad bytes\n", pad);
+                        segment->total_size += pad;
+                        segment->size = pad;
+                        segment->data = padbuf;
+                        return 0;
+                }
         }
 
         /*
@@ -273,7 +277,7 @@ iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
 {
         unsigned int copy = 0, copied = 0;
 
-        while (!iscsi_tcp_segment_done(segment, 1, copy)) {
+        while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
                 if (copied == len) {
                         debug_tcp("iscsi_tcp_segment_recv copied %d bytes\n",
                                   len);
@@ -794,7 +798,8 @@ iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
         /* We're done processing the header. See if we're doing
          * header digests; if so, set up the recv_digest buffer
          * and go back for more. */
-        if (conn->hdrdgst_en) {
+        if (conn->hdrdgst_en &&
+            !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
                 if (segment->digest_len == 0) {
                         /*
                          * Even if we offload the digest processing we
@@ -806,14 +811,12 @@ iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
                         return 0;
                 }
 
-                if (!(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
-                        iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
-                                segment->total_copied - ISCSI_DIGEST_SIZE,
-                                segment->digest);
+                iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
+                                      segment->total_copied - ISCSI_DIGEST_SIZE,
+                                      segment->digest);
 
-                        if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
-                                return ISCSI_ERR_HDR_DGST;
-                }
+                if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
+                        return ISCSI_ERR_HDR_DGST;
         }
 
         tcp_conn->in.hdr = hdr;
diff --git a/include/scsi/iscsi_if.h b/include/scsi/iscsi_if.h
index 8e008c96e795..d0ed5226f8c4 100644
--- a/include/scsi/iscsi_if.h
+++ b/include/scsi/iscsi_if.h
@@ -336,6 +336,8 @@ enum iscsi_host_param {
 #define CAP_SENDTARGETS_OFFLOAD 0x400   /* offload discovery process */
 #define CAP_DATA_PATH_OFFLOAD   0x800   /* offload entire IO path */
 #define CAP_DIGEST_OFFLOAD      0x1000  /* offload hdr and data digests */
+#define CAP_PADDING_OFFLOAD     0x2000  /* offload padding insertion, removal,
+                                         and verification */
 
 /*
  * These flags describes reason of stop_conn() call
diff --git a/include/scsi/libiscsi_tcp.h b/include/scsi/libiscsi_tcp.h
index e6bf8ef276bb..83e32f6d7859 100644
--- a/include/scsi/libiscsi_tcp.h
+++ b/include/scsi/libiscsi_tcp.h
@@ -99,7 +99,8 @@ extern int iscsi_tcp_task_xmit(struct iscsi_task *task);
 
 /* segment helpers */
 extern int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn);
-extern int iscsi_tcp_segment_done(struct iscsi_segment *segment, int recv,
+extern int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
+                                  struct iscsi_segment *segment, int recv,
                                   unsigned copied);
 extern void iscsi_tcp_segment_unmap(struct iscsi_segment *segment);