[SCSI] libiscsi, iscsi_tcp, iser: add session cmds array accessor

Currently to get a ctask from the session cmd array, you have to
know to use the itt modifier. To make this easier on LLDs and
so in the future we can easilly kill the session array and use
the host shared map instead, this patch adds a nice wrapper
to strip the itt into a session->cmds index and return a ctask.

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

2 files changed, 52 insertions, 21 deletions

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index dfaf9fa5734..f2a08f7ed90 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -740,7 +740,6 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 	struct iscsi_session *session = conn->session;
 	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 	struct iscsi_cmd_task *ctask;
-	uint32_t itt;
 
 	/* verify PDU length */
 	tcp_conn->in.datalen = ntoh24(hdr->dlength);
@@ -758,7 +757,7 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 
 	opcode = hdr->opcode & ISCSI_OPCODE_MASK;
 	/* verify itt (itt encoding: age+cid+itt) */
-	rc = iscsi_verify_itt(conn, hdr, &itt);
+	rc = iscsi_verify_itt(conn, hdr->itt);
 	if (rc)
 		return rc;
 
@@ -767,7 +766,10 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 
 	switch(opcode) {
 	case ISCSI_OP_SCSI_DATA_IN:
-		ctask = session->cmds[itt];
+		ctask = iscsi_itt_to_ctask(conn, hdr->itt);
+		if (!ctask)
+			return ISCSI_ERR_BAD_ITT;
+
 		spin_lock(&conn->session->lock);
 		rc = iscsi_data_rsp(conn, ctask);
 		spin_unlock(&conn->session->lock);
@@ -810,7 +812,10 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 		break;
 	case ISCSI_OP_R2T:
-		ctask = session->cmds[itt];
+		ctask = iscsi_itt_to_ctask(conn, hdr->itt);
+		if (!ctask)
+			return ISCSI_ERR_BAD_ITT;
+
 		if (ahslen)
 			rc = ISCSI_ERR_AHSLEN;
 		else if (ctask->sc->sc_data_direction == DMA_TO_DEVICE) {
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 79bc49fd7f1..4bc63c4b3c1 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -640,6 +640,10 @@ static int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	uint32_t itt;
 
 	conn->last_recv = jiffies;
+	rc = iscsi_verify_itt(conn, hdr->itt);
+	if (rc)
+		return rc;
+
 	if (hdr->itt != RESERVED_ITT)
 		itt = get_itt(hdr->itt);
 	else
@@ -776,27 +780,22 @@ int iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 }
 EXPORT_SYMBOL_GPL(iscsi_complete_pdu);
 
-/* verify itt (itt encoding: age+cid+itt) */
-int iscsi_verify_itt(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
-		     uint32_t *ret_itt)
+int iscsi_verify_itt(struct iscsi_conn *conn, itt_t itt)
 {
 	struct iscsi_session *session = conn->session;
 	struct iscsi_cmd_task *ctask;
-	uint32_t itt;
 
-	if (hdr->itt != RESERVED_ITT) {
-		if (((__force u32)hdr->itt & ISCSI_AGE_MASK) !=
-		    (session->age << ISCSI_AGE_SHIFT)) {
-			iscsi_conn_printk(KERN_ERR, conn,
-					  "received itt %x expected session "
-					  "age (%x)\n", (__force u32)hdr->itt,
-					  session->age & ISCSI_AGE_MASK);
-			return ISCSI_ERR_BAD_ITT;
-		}
+	if (itt == RESERVED_ITT)
+		return 0;
 
-		itt = get_itt(hdr->itt);
-	} else
-		itt = ~0U;
+	if (((__force u32)itt & ISCSI_AGE_MASK) !=
+	    (session->age << ISCSI_AGE_SHIFT)) {
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "received itt %x expected session age (%x)\n",
+				  (__force u32)itt,
+				  session->age & ISCSI_AGE_MASK);
+		return ISCSI_ERR_BAD_ITT;
+	}
 
 	if (itt < session->cmds_max) {
 		ctask = session->cmds[itt];
@@ -817,11 +816,38 @@ int iscsi_verify_itt(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		}
 	}
 
-	*ret_itt = itt;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(iscsi_verify_itt);
 
+struct iscsi_cmd_task *
+iscsi_itt_to_ctask(struct iscsi_conn *conn, itt_t itt)
+{
+	struct iscsi_session *session = conn->session;
+	struct iscsi_cmd_task *ctask;
+	uint32_t i;
+
+	if (iscsi_verify_itt(conn, itt))
+		return NULL;
+
+	if (itt == RESERVED_ITT)
+		return NULL;
+
+	i = get_itt(itt);
+	if (i >= session->cmds_max)
+		return NULL;
+
+	ctask = session->cmds[i];
+	if (!ctask->sc)
+		return NULL;
+
+	if (ctask->sc->SCp.phase != session->age)
+		return NULL;
+
+	return ctask;
+}
+EXPORT_SYMBOL_GPL(iscsi_itt_to_ctask);
+
 void iscsi_conn_failure(struct iscsi_conn *conn, enum iscsi_err err)
 {
 	struct iscsi_session *session = conn->session;