9 files changed, 206 insertions, 161 deletions

diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index 3cd4693bc2b4..9be818f7b26d 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -233,20 +233,20 @@ static int beiscsi_eh_abort(struct scsi_cmnd *sc)
 	cls_session = starget_to_session(scsi_target(sc->device));
 	session = cls_session->dd_data;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (!aborted_task || !aborted_task->sc) {
 		/* we raced */
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		return SUCCESS;
 	}
 
 	aborted_io_task = aborted_task->dd_data;
 	if (!aborted_io_task->scsi_cmnd) {
 		/* raced or invalid command */
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		return SUCCESS;
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	/* Invalidate WRB Posted for this Task */
 	AMAP_SET_BITS(struct amap_iscsi_wrb, invld,
 		      aborted_io_task->pwrb_handle->pwrb,
@@ -311,9 +311,9 @@ static int beiscsi_eh_device_reset(struct scsi_cmnd *sc)
 	/* invalidate iocbs */
 	cls_session = starget_to_session(scsi_target(sc->device));
 	session = cls_session->dd_data;
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		return FAILED;
 	}
 	conn = session->leadconn;
@@ -342,7 +342,7 @@ static int beiscsi_eh_device_reset(struct scsi_cmnd *sc)
 		num_invalidate++;
 		inv_tbl++;
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	inv_tbl = phba->inv_tbl;
 
 	nonemb_cmd.va = pci_alloc_consistent(phba->ctrl.pdev,
@@ -1185,9 +1185,9 @@ beiscsi_process_async_pdu(struct beiscsi_conn *beiscsi_conn,
 		return 1;
 	}
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->back_lock);
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)ppdu, pbuffer, buf_len);
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->back_lock);
 	return 0;
 }
 
@@ -1606,7 +1606,7 @@ static void hwi_complete_cmd(struct beiscsi_conn *beiscsi_conn,
 	pwrb = pwrb_handle->pwrb;
 	type = ((struct beiscsi_io_task *)task->dd_data)->wrb_type;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->back_lock);
 	switch (type) {
 	case HWH_TYPE_IO:
 	case HWH_TYPE_IO_RD:
@@ -1645,7 +1645,7 @@ static void hwi_complete_cmd(struct beiscsi_conn *beiscsi_conn,
 		break;
 	}
 
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->back_lock);
 }
 
 static struct list_head *hwi_get_async_busy_list(struct hwi_async_pdu_context
@@ -4693,9 +4693,9 @@ beiscsi_offload_connection(struct beiscsi_conn *beiscsi_conn,
 	 * login/startup related tasks.
 	 */
 	beiscsi_conn->login_in_progress = 0;
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->back_lock);
 	beiscsi_cleanup_task(task);
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->back_lock);
 
 	pwrb_handle = alloc_wrb_handle(phba, beiscsi_conn->beiscsi_conn_cid);
 
diff --git a/drivers/scsi/bnx2i/bnx2i_hwi.c b/drivers/scsi/bnx2i/bnx2i_hwi.c
index e4cf23df4b4f..da9cf041dc5d 100644
--- a/drivers/scsi/bnx2i/bnx2i_hwi.c
+++ b/drivers/scsi/bnx2i/bnx2i_hwi.c
@@ -1361,7 +1361,7 @@ int bnx2i_process_scsi_cmd_resp(struct iscsi_session *session,
 	u32 datalen = 0;
 
 	resp_cqe = (struct bnx2i_cmd_response *)cqe;
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 				 resp_cqe->itt & ISCSI_CMD_RESPONSE_INDEX);
 	if (!task)
@@ -1432,7 +1432,7 @@ done:
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)hdr,
 			     conn->data, datalen);
 fail:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->back_lock);
 	return 0;
 }
 
@@ -1457,7 +1457,7 @@ static int bnx2i_process_login_resp(struct iscsi_session *session,
 	int pad_len;
 
 	login = (struct bnx2i_login_response *) cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 				 login->itt & ISCSI_LOGIN_RESPONSE_INDEX);
 	if (!task)
@@ -1500,7 +1500,7 @@ static int bnx2i_process_login_resp(struct iscsi_session *session,
 		bnx2i_conn->gen_pdu.resp_buf,
 		bnx2i_conn->gen_pdu.resp_wr_ptr - bnx2i_conn->gen_pdu.resp_buf);
 done:
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 	return 0;
 }
 
@@ -1525,7 +1525,7 @@ static int bnx2i_process_text_resp(struct iscsi_session *session,
 	int pad_len;
 
 	text = (struct bnx2i_text_response *) cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn, text->itt & ISCSI_LOGIN_RESPONSE_INDEX);
 	if (!task)
 		goto done;
@@ -1561,7 +1561,7 @@ static int bnx2i_process_text_resp(struct iscsi_session *session,
 			     bnx2i_conn->gen_pdu.resp_wr_ptr -
 			     bnx2i_conn->gen_pdu.resp_buf);
 done:
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 	return 0;
 }
 
@@ -1584,7 +1584,7 @@ static int bnx2i_process_tmf_resp(struct iscsi_session *session,
 	struct iscsi_tm_rsp *resp_hdr;
 
 	tmf_cqe = (struct bnx2i_tmf_response *)cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 				 tmf_cqe->itt & ISCSI_TMF_RESPONSE_INDEX);
 	if (!task)
@@ -1600,7 +1600,7 @@ static int bnx2i_process_tmf_resp(struct iscsi_session *session,
 
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)resp_hdr, NULL, 0);
 done:
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 	return 0;
 }
 
@@ -1623,7 +1623,7 @@ static int bnx2i_process_logout_resp(struct iscsi_session *session,
 	struct iscsi_logout_rsp *resp_hdr;
 
 	logout = (struct bnx2i_logout_response *) cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 				 logout->itt & ISCSI_LOGOUT_RESPONSE_INDEX);
 	if (!task)
@@ -1647,7 +1647,7 @@ static int bnx2i_process_logout_resp(struct iscsi_session *session,
 
 	bnx2i_conn->ep->state = EP_STATE_LOGOUT_RESP_RCVD;
 done:
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 	return 0;
 }
 
@@ -1668,12 +1668,12 @@ static void bnx2i_process_nopin_local_cmpl(struct iscsi_session *session,
 	struct iscsi_task *task;
 
 	nop_in = (struct bnx2i_nop_in_msg *)cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 				 nop_in->itt & ISCSI_NOP_IN_MSG_INDEX);
 	if (task)
 		__iscsi_put_task(task);
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 }
 
 /**
@@ -1712,7 +1712,7 @@ static int bnx2i_process_nopin_mesg(struct iscsi_session *session,
 
 	nop_in = (struct bnx2i_nop_in_msg *)cqe;
 
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	hdr = (struct iscsi_nopin *)&bnx2i_conn->gen_pdu.resp_hdr;
 	memset(hdr, 0, sizeof(struct iscsi_hdr));
 	hdr->opcode = nop_in->op_code;
@@ -1738,7 +1738,7 @@ static int bnx2i_process_nopin_mesg(struct iscsi_session *session,
 	}
 done:
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)hdr, NULL, 0);
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 
 	return tgt_async_nop;
 }
@@ -1771,7 +1771,7 @@ static void bnx2i_process_async_mesg(struct iscsi_session *session,
 		return;
 	}
 
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	resp_hdr = (struct iscsi_async *) &bnx2i_conn->gen_pdu.resp_hdr;
 	memset(resp_hdr, 0, sizeof(struct iscsi_hdr));
 	resp_hdr->opcode = async_cqe->op_code;
@@ -1790,7 +1790,7 @@ static void bnx2i_process_async_mesg(struct iscsi_session *session,
 
 	__iscsi_complete_pdu(bnx2i_conn->cls_conn->dd_data,
 			     (struct iscsi_hdr *)resp_hdr, NULL, 0);
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 }
 
 
@@ -1817,7 +1817,7 @@ static void bnx2i_process_reject_mesg(struct iscsi_session *session,
 	} else
 		bnx2i_unsol_pdu_adjust_rq(bnx2i_conn);
 
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	hdr = (struct iscsi_reject *) &bnx2i_conn->gen_pdu.resp_hdr;
 	memset(hdr, 0, sizeof(struct iscsi_hdr));
 	hdr->opcode = reject->op_code;
@@ -1828,7 +1828,7 @@ static void bnx2i_process_reject_mesg(struct iscsi_session *session,
 	hdr->ffffffff = cpu_to_be32(RESERVED_ITT);
 	__iscsi_complete_pdu(conn, (struct iscsi_hdr *)hdr, conn->data,
 			     reject->data_length);
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 }
 
 /**
@@ -1848,13 +1848,13 @@ static void bnx2i_process_cmd_cleanup_resp(struct iscsi_session *session,
 	struct iscsi_task *task;
 
 	cmd_clean_rsp = (struct bnx2i_cleanup_response *)cqe;
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(conn,
 			cmd_clean_rsp->itt & ISCSI_CLEANUP_RESPONSE_INDEX);
 	if (!task)
 		printk(KERN_ALERT "bnx2i: cmd clean ITT %x not active\n",
 			cmd_clean_rsp->itt & ISCSI_CLEANUP_RESPONSE_INDEX);
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 	complete(&bnx2i_conn->cmd_cleanup_cmpl);
 }
 
@@ -1921,11 +1921,11 @@ static int bnx2i_queue_scsi_cmd_resp(struct iscsi_session *session,
 	int rc = 0;
 	int cpu;
 
-	spin_lock(&session->lock);
+	spin_lock(&session->back_lock);
 	task = iscsi_itt_to_task(bnx2i_conn->cls_conn->dd_data,
 				 cqe->itt & ISCSI_CMD_RESPONSE_INDEX);
 	if (!task || !task->sc) {
-		spin_unlock(&session->lock);
+		spin_unlock(&session->back_lock);
 		return -EINVAL;
 	}
 	sc = task->sc;
@@ -1935,7 +1935,7 @@ static int bnx2i_queue_scsi_cmd_resp(struct iscsi_session *session,
 	else
 		cpu = sc->request->cpu;
 
-	spin_unlock(&session->lock);
+	spin_unlock(&session->back_lock);
 
 	p = &per_cpu(bnx2i_percpu, cpu);
 	spin_lock(&p->p_work_lock);
diff --git a/drivers/scsi/bnx2i/bnx2i_iscsi.c b/drivers/scsi/bnx2i/bnx2i_iscsi.c
index 854dad7d5b03..c00642f10f1f 100644
--- a/drivers/scsi/bnx2i/bnx2i_iscsi.c
+++ b/drivers/scsi/bnx2i/bnx2i_iscsi.c
@@ -1169,10 +1169,10 @@ static void bnx2i_cleanup_task(struct iscsi_task *task)
 	if (task->state == ISCSI_TASK_ABRT_TMF) {
 		bnx2i_send_cmd_cleanup_req(hba, task->dd_data);
 
-		spin_unlock_bh(&conn->session->lock);
+		spin_unlock_bh(&conn->session->back_lock);
 		wait_for_completion_timeout(&bnx2i_conn->cmd_cleanup_cmpl,
 				msecs_to_jiffies(ISCSI_CMD_CLEANUP_TIMEOUT));
-		spin_lock_bh(&conn->session->lock);
+		spin_lock_bh(&conn->session->back_lock);
 	}
 	bnx2i_iscsi_unmap_sg_list(task->dd_data);
 }
@@ -2059,7 +2059,7 @@ int bnx2i_hw_ep_disconnect(struct bnx2i_endpoint *bnx2i_ep)
 		goto out;
 
 	if (session) {
-		spin_lock_bh(&session->lock);
+		spin_lock_bh(&session->frwd_lock);
 		if (bnx2i_ep->state != EP_STATE_TCP_FIN_RCVD) {
 			if (session->state == ISCSI_STATE_LOGGING_OUT) {
 				if (bnx2i_ep->state == EP_STATE_LOGOUT_SENT) {
@@ -2075,7 +2075,7 @@ int bnx2i_hw_ep_disconnect(struct bnx2i_endpoint *bnx2i_ep)
 		} else
 			close = 1;
 
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 	}
 
 	bnx2i_ep->state = EP_STATE_DISCONN_START;
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index add6d1566ec8..12b351213c59 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -593,9 +593,9 @@ static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn)
 	iscsi_sw_tcp_conn_restore_callbacks(conn);
 	sock_put(sock->sk);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	tcp_sw_conn->sock = NULL;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	sockfd_put(sock);
 }
 
@@ -663,10 +663,10 @@ iscsi_sw_tcp_conn_bind(struct iscsi_cls_session *cls_session,
 	if (err)
 		goto free_socket;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	/* bind iSCSI connection and socket */
 	tcp_sw_conn->sock = sock;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	/* setup Socket parameters */
 	sk = sock->sk;
@@ -726,14 +726,14 @@ static int iscsi_sw_tcp_conn_get_param(struct iscsi_cls_conn *cls_conn,
 	switch(param) {
 	case ISCSI_PARAM_CONN_PORT:
 	case ISCSI_PARAM_CONN_ADDRESS:
-		spin_lock_bh(&conn->session->lock);
+		spin_lock_bh(&conn->session->frwd_lock);
 		if (!tcp_sw_conn || !tcp_sw_conn->sock) {
-			spin_unlock_bh(&conn->session->lock);
+			spin_unlock_bh(&conn->session->frwd_lock);
 			return -ENOTCONN;
 		}
 		rc = kernel_getpeername(tcp_sw_conn->sock,
 					(struct sockaddr *)&addr, &len);
-		spin_unlock_bh(&conn->session->lock);
+		spin_unlock_bh(&conn->session->frwd_lock);
 		if (rc)
 			return rc;
 
@@ -759,23 +759,23 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
 
 	switch (param) {
 	case ISCSI_HOST_PARAM_IPADDRESS:
-		spin_lock_bh(&session->lock);
+		spin_lock_bh(&session->frwd_lock);
 		conn = session->leadconn;
 		if (!conn) {
-			spin_unlock_bh(&session->lock);
+			spin_unlock_bh(&session->frwd_lock);
 			return -ENOTCONN;
 		}
 		tcp_conn = conn->dd_data;
 
 		tcp_sw_conn = tcp_conn->dd_data;
 		if (!tcp_sw_conn->sock) {
-			spin_unlock_bh(&session->lock);
+			spin_unlock_bh(&session->frwd_lock);
 			return -ENOTCONN;
 		}
 
 		rc = kernel_getsockname(tcp_sw_conn->sock,
 					(struct sockaddr *)&addr, &len);
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		if (rc)
 			return rc;
 
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index cd330c0e0fd5..8738b989a801 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -481,7 +481,7 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
  * iscsi_free_task - free a task
  * @task: iscsi cmd task
  *
- * Must be called with session lock.
+ * Must be called with session back_lock.
  * This function returns the scsi command to scsi-ml or cleans
  * up mgmt tasks then returns the task to the pool.
  */
@@ -535,9 +535,10 @@ void iscsi_put_task(struct iscsi_task *task)
 {
 	struct iscsi_session *session = task->conn->session;
 
-	spin_lock_bh(&session->lock);
+	/* regular RX path uses back_lock */
+	spin_lock_bh(&session->back_lock);
 	__iscsi_put_task(task);
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->back_lock);
 }
 EXPORT_SYMBOL_GPL(iscsi_put_task);
 
@@ -546,7 +547,7 @@ EXPORT_SYMBOL_GPL(iscsi_put_task);
  * @task: iscsi cmd task
  * @state: state to complete task with
  *
- * Must be called with session lock.
+ * Must be called with session back_lock.
  */
 static void iscsi_complete_task(struct iscsi_task *task, int state)
 {
@@ -585,7 +586,7 @@ static void iscsi_complete_task(struct iscsi_task *task, int state)
  * This is used when drivers do not need or cannot perform
  * lower level pdu processing.
  *
- * Called with session lock
+ * Called with session back_lock
  */
 void iscsi_complete_scsi_task(struct iscsi_task *task,
 			      uint32_t exp_cmdsn, uint32_t max_cmdsn)
@@ -602,7 +603,7 @@ EXPORT_SYMBOL_GPL(iscsi_complete_scsi_task);
 
 
 /*
- * session lock must be held and if not called for a task that is
+ * session back_lock must be held and if not called for a task that is
  * still pending or from the xmit thread, then xmit thread must
  * be suspended.
  */
@@ -642,7 +643,10 @@ static void fail_scsi_task(struct iscsi_task *task, int err)
 		scsi_in(sc)->resid = scsi_in(sc)->length;
 	}
 
+	/* regular RX path uses back_lock */
+	spin_lock_bh(&conn->session->back_lock);
 	iscsi_complete_task(task, state);
+	spin_unlock_bh(&conn->session->back_lock);
 }
 
 static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
@@ -780,7 +784,10 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 	return task;
 
 free_task:
+	/* regular RX path uses back_lock */
+	spin_lock_bh(&session->back_lock);
 	__iscsi_put_task(task);
+	spin_unlock_bh(&session->back_lock);
 	return NULL;
 }
 
@@ -791,10 +798,10 @@ int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
 	struct iscsi_session *session = conn->session;
 	int err = 0;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (!__iscsi_conn_send_pdu(conn, hdr, data, data_size))
 		err = -EPERM;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_send_pdu);
@@ -1031,14 +1038,19 @@ static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 		if (opcode != ISCSI_OP_NOOP_OUT)
 			return 0;
 
-		 if (rejected_pdu.itt == cpu_to_be32(ISCSI_RESERVED_TAG))
+		 if (rejected_pdu.itt == cpu_to_be32(ISCSI_RESERVED_TAG)) {
 			/*
 			 * nop-out in response to target's nop-out rejected.
 			 * Just resend.
 			 */
+			/* In RX path we are under back lock */
+			spin_unlock(&conn->session->back_lock);
+			spin_lock(&conn->session->frwd_lock);
 			iscsi_send_nopout(conn,
 					  (struct iscsi_nopin*)&rejected_pdu);
-		else {
+			spin_unlock(&conn->session->frwd_lock);
+			spin_lock(&conn->session->back_lock);
+		} else {
 			struct iscsi_task *task;
 			/*
 			 * Our nop as ping got dropped. We know the target
@@ -1074,7 +1086,7 @@ static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
  * This should be used for mgmt tasks like login and nops, or if
  * the LDD's itt space does not include the session age.
  *
- * The session lock must be held.
+ * The session back_lock must be held.
  */
 struct iscsi_task *iscsi_itt_to_task(struct iscsi_conn *conn, itt_t itt)
 {
@@ -1103,7 +1115,7 @@ EXPORT_SYMBOL_GPL(iscsi_itt_to_task);
  * @datalen: len of data buffer
  *
  * Completes pdu processing by freeing any resources allocated at
- * queuecommand or send generic. session lock must be held and verify
+ * queuecommand or send generic. session back_lock must be held and verify
  * itt must have been called.
  */
 int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
@@ -1140,7 +1152,12 @@ int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 			if (hdr->ttt == cpu_to_be32(ISCSI_RESERVED_TAG))
 				break;
 
+			/* In RX path we are under back lock */
+			spin_unlock(&session->back_lock);
+			spin_lock(&session->frwd_lock);
 			iscsi_send_nopout(conn, (struct iscsi_nopin*)hdr);
+			spin_unlock(&session->frwd_lock);
+			spin_lock(&session->back_lock);
 			break;
 		case ISCSI_OP_REJECT:
 			rc = iscsi_handle_reject(conn, hdr, data, datalen);
@@ -1247,9 +1264,9 @@ int iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
 {
 	int rc;
 
-	spin_lock(&conn->session->lock);
+	spin_lock(&conn->session->back_lock);
 	rc = __iscsi_complete_pdu(conn, hdr, data, datalen);
-	spin_unlock(&conn->session->lock);
+	spin_unlock(&conn->session->back_lock);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(iscsi_complete_pdu);
@@ -1293,7 +1310,7 @@ EXPORT_SYMBOL_GPL(iscsi_verify_itt);
  *
  * This should be used for cmd tasks.
  *
- * The session lock must be held.
+ * The session back_lock must be held.
  */
 struct iscsi_task *iscsi_itt_to_ctask(struct iscsi_conn *conn, itt_t itt)
 {
@@ -1323,15 +1340,15 @@ void iscsi_session_failure(struct iscsi_session *session,
 	struct iscsi_conn *conn;
 	struct device *dev;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	conn = session->leadconn;
 	if (session->state == ISCSI_STATE_TERMINATE || !conn) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		return;
 	}
 
 	dev = get_device(&conn->cls_conn->dev);
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	if (!dev)
 	        return;
 	/*
@@ -1351,15 +1368,15 @@ void iscsi_conn_failure(struct iscsi_conn *conn, enum iscsi_err err)
 {
 	struct iscsi_session *session = conn->session;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (session->state == ISCSI_STATE_FAILED) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		return;
 	}
 
 	if (conn->stop_stage == 0)
 		session->state = ISCSI_STATE_FAILED;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
 	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
@@ -1393,15 +1410,18 @@ static int iscsi_xmit_task(struct iscsi_conn *conn)
 		return -ENODATA;
 
 	__iscsi_get_task(task);
-	spin_unlock_bh(&conn->session->lock);
+	spin_unlock_bh(&conn->session->frwd_lock);
 	rc = conn->session->tt->xmit_task(task);
-	spin_lock_bh(&conn->session->lock);
+	spin_lock_bh(&conn->session->frwd_lock);
 	if (!rc) {
 		/* done with this task */
 		task->last_xfer = jiffies;
 		conn->task = NULL;
 	}
+	/* regular RX path uses back_lock */
+	spin_lock_bh(&conn->session->back_lock);
 	__iscsi_put_task(task);
+	spin_unlock_bh(&conn->session->back_lock);
 	return rc;
 }
 
@@ -1410,7 +1430,7 @@ static int iscsi_xmit_task(struct iscsi_conn *conn)
  * @task: task to requeue
  *
  * LLDs that need to run a task from the session workqueue should call
- * this. The session lock must be held. This should only be called
+ * this. The session frwd_lock must be held. This should only be called
  * by software drivers.
  */
 void iscsi_requeue_task(struct iscsi_task *task)
@@ -1441,10 +1461,10 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
 	struct iscsi_task *task;
 	int rc = 0;
 
-	spin_lock_bh(&conn->session->lock);
+	spin_lock_bh(&conn->session->frwd_lock);
 	if (test_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx)) {
 		ISCSI_DBG_SESSION(conn->session, "Tx suspended!\n");
-		spin_unlock_bh(&conn->session->lock);
+		spin_unlock_bh(&conn->session->frwd_lock);
 		return -ENODATA;
 	}
 
@@ -1465,7 +1485,10 @@ check_mgmt:
 					 struct iscsi_task, running);
 		list_del_init(&conn->task->running);
 		if (iscsi_prep_mgmt_task(conn, conn->task)) {
+			/* regular RX path uses back_lock */
+			spin_lock_bh(&conn->session->back_lock);
 			__iscsi_put_task(conn->task);
+			spin_unlock_bh(&conn->session->back_lock);
 			conn->task = NULL;
 			continue;
 		}
@@ -1527,11 +1550,11 @@ check_mgmt:
 		if (!list_empty(&conn->mgmtqueue))
 			goto check_mgmt;
 	}
-	spin_unlock_bh(&conn->session->lock);
+	spin_unlock_bh(&conn->session->frwd_lock);
 	return -ENODATA;
 
 done:
-	spin_unlock_bh(&conn->session->lock);
+	spin_unlock_bh(&conn->session->frwd_lock);
 	return rc;
 }
 
@@ -1600,7 +1623,7 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
 
 	cls_session = starget_to_session(scsi_target(sc->device));
 	session = cls_session->dd_data;
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 
 	reason = iscsi_session_chkready(cls_session);
 	if (reason) {
@@ -1686,13 +1709,13 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
 	}
 
 	session->queued_cmdsn++;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	return 0;
 
 prepd_reject:
 	iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
 reject:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n",
 			  sc->cmnd[0], reason);
 	return SCSI_MLQUEUE_TARGET_BUSY;
@@ -1700,7 +1723,7 @@ reject:
 prepd_fault:
 	iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
 fault:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n",
 			  sc->cmnd[0], reason);
 	if (!scsi_bidi_cmnd(sc))
@@ -1748,14 +1771,14 @@ static void iscsi_tmf_timedout(unsigned long data)
 	struct iscsi_conn *conn = (struct iscsi_conn *)data;
 	struct iscsi_session *session = conn->session;
 
-	spin_lock(&session->lock);
+	spin_lock(&session->frwd_lock);
 	if (conn->tmf_state == TMF_QUEUED) {
 		conn->tmf_state = TMF_TIMEDOUT;
 		ISCSI_DBG_EH(session, "tmf timedout\n");
 		/* unblock eh_abort() */
 		wake_up(&conn->ehwait);
 	}
-	spin_unlock(&session->lock);
+	spin_unlock(&session->frwd_lock);
 }
 
 static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
@@ -1768,10 +1791,10 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 	task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr,
 				      NULL, 0);
 	if (!task) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		iscsi_conn_printk(KERN_ERR, conn, "Could not send TMF.\n");
 		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
-		spin_lock_bh(&session->lock);
+		spin_lock_bh(&session->frwd_lock);
 		return -EPERM;
 	}
 	conn->tmfcmd_pdus_cnt++;
@@ -1781,7 +1804,7 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 	add_timer(&conn->tmf_timer);
 	ISCSI_DBG_EH(session, "tmf set timeout\n");
 
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	mutex_unlock(&session->eh_mutex);
 
 	/*
@@ -1800,7 +1823,7 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 	del_timer_sync(&conn->tmf_timer);
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	/* if the session drops it will clean up the task */
 	if (age != session->age ||
 	    session->state != ISCSI_STATE_LOGGED_IN)
@@ -1837,7 +1860,7 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, unsigned lun,
  * iscsi_suspend_queue - suspend iscsi_queuecommand
  * @conn: iscsi conn to stop queueing IO on
  *
- * This grabs the session lock to make sure no one is in
+ * This grabs the session frwd_lock to make sure no one is in
  * xmit_task/queuecommand, and then sets suspend to prevent
  * new commands from being queued. This only needs to be called
  * by offload drivers that need to sync a path like ep disconnect
@@ -1846,9 +1869,9 @@ static void fail_scsi_tasks(struct iscsi_conn *conn, unsigned lun,
  */
 void iscsi_suspend_queue(struct iscsi_conn *conn)
 {
-	spin_lock_bh(&conn->session->lock);
+	spin_lock_bh(&conn->session->frwd_lock);
 	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-	spin_unlock_bh(&conn->session->lock);
+	spin_unlock_bh(&conn->session->frwd_lock);
 }
 EXPORT_SYMBOL_GPL(iscsi_suspend_queue);
 
@@ -1907,7 +1930,7 @@ static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
 
 	ISCSI_DBG_EH(session, "scsi cmd %p timedout\n", sc);
 
-	spin_lock(&session->lock);
+	spin_lock(&session->frwd_lock);
 	task = (struct iscsi_task *)sc->SCp.ptr;
 	if (!task) {
 		/*
@@ -2021,7 +2044,7 @@ static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
 done:
 	if (task)
 		task->last_timeout = jiffies;
-	spin_unlock(&session->lock);
+	spin_unlock(&session->frwd_lock);
 	ISCSI_DBG_EH(session, "return %s\n", rc == BLK_EH_RESET_TIMER ?
 		     "timer reset" : "nh");
 	return rc;
@@ -2033,7 +2056,7 @@ static void iscsi_check_transport_timeouts(unsigned long data)
 	struct iscsi_session *session = conn->session;
 	unsigned long recv_timeout, next_timeout = 0, last_recv;
 
-	spin_lock(&session->lock);
+	spin_lock(&session->frwd_lock);
 	if (session->state != ISCSI_STATE_LOGGED_IN)
 		goto done;
 
@@ -2050,7 +2073,7 @@ static void iscsi_check_transport_timeouts(unsigned long data)
 				  "last ping %lu, now %lu\n",
 				  conn->ping_timeout, conn->recv_timeout,
 				  last_recv, conn->last_ping, jiffies);
-		spin_unlock(&session->lock);
+		spin_unlock(&session->frwd_lock);
 		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
 		return;
 	}
@@ -2066,7 +2089,7 @@ static void iscsi_check_transport_timeouts(unsigned long data)
 	ISCSI_DBG_CONN(conn, "Setting next tmo %lu\n", next_timeout);
 	mod_timer(&conn->transport_timer, next_timeout);
 done:
-	spin_unlock(&session->lock);
+	spin_unlock(&session->frwd_lock);
 }
 
 static void iscsi_prep_abort_task_pdu(struct iscsi_task *task,
@@ -2096,7 +2119,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 	ISCSI_DBG_EH(session, "aborting sc %p\n", sc);
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	/*
 	 * if session was ISCSI_STATE_IN_RECOVERY then we may not have
 	 * got the command.
@@ -2104,7 +2127,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 	if (!sc->SCp.ptr) {
 		ISCSI_DBG_EH(session, "sc never reached iscsi layer or "
 				      "it completed.\n");
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		mutex_unlock(&session->eh_mutex);
 		return SUCCESS;
 	}
@@ -2115,7 +2138,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 	 */
 	if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN ||
 	    sc->SCp.phase != session->age) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		mutex_unlock(&session->eh_mutex);
 		ISCSI_DBG_EH(session, "failing abort due to dropped "
 				  "session.\n");
@@ -2156,7 +2179,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 
 	switch (conn->tmf_state) {
 	case TMF_SUCCESS:
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		/*
 		 * stop tx side incase the target had sent a abort rsp but
 		 * the initiator was still writing out data.
@@ -2167,15 +2190,15 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 		 * good and have never sent us a successful tmf response
 		 * then sent more data for the cmd.
 		 */
-		spin_lock_bh(&session->lock);
+		spin_lock_bh(&session->frwd_lock);
 		fail_scsi_task(task, DID_ABORT);
 		conn->tmf_state = TMF_INITIAL;
 		memset(hdr, 0, sizeof(*hdr));
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		iscsi_start_tx(conn);
 		goto success_unlocked;
 	case TMF_TIMEDOUT:
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto failed_unlocked;
 	case TMF_NOT_FOUND:
@@ -2194,7 +2217,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
 	}
 
 success:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 success_unlocked:
 	ISCSI_DBG_EH(session, "abort success [sc %p itt 0x%x]\n",
 		     sc, task->itt);
@@ -2202,7 +2225,7 @@ success_unlocked:
 	return SUCCESS;
 
 failed:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 failed_unlocked:
 	ISCSI_DBG_EH(session, "abort failed [sc %p itt 0x%x]\n", sc,
 		     task ? task->itt : 0);
@@ -2235,7 +2258,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 	ISCSI_DBG_EH(session, "LU Reset [sc %p lun %u]\n", sc, sc->device->lun);
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	/*
 	 * Just check if we are not logged in. We cannot check for
 	 * the phase because the reset could come from a ioctl.
@@ -2262,7 +2285,7 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 	case TMF_SUCCESS:
 		break;
 	case TMF_TIMEDOUT:
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto done;
 	default:
@@ -2271,21 +2294,21 @@ int iscsi_eh_device_reset(struct scsi_cmnd *sc)
 	}
 
 	rc = SUCCESS;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_suspend_tx(conn);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	memset(hdr, 0, sizeof(*hdr));
 	fail_scsi_tasks(conn, sc->device->lun, DID_ERROR);
 	conn->tmf_state = TMF_INITIAL;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_start_tx(conn);
 	goto done;
 
 unlock:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 done:
 	ISCSI_DBG_EH(session, "dev reset result = %s\n",
 		     rc == SUCCESS ? "SUCCESS" : "FAILED");
@@ -2298,13 +2321,13 @@ void iscsi_session_recovery_timedout(struct iscsi_cls_session *cls_session)
 {
 	struct iscsi_session *session = cls_session->dd_data;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (session->state != ISCSI_STATE_LOGGED_IN) {
 		session->state = ISCSI_STATE_RECOVERY_FAILED;
 		if (session->leadconn)
 			wake_up(&session->leadconn->ehwait);
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 }
 EXPORT_SYMBOL_GPL(iscsi_session_recovery_timedout);
 
@@ -2326,19 +2349,19 @@ int iscsi_eh_session_reset(struct scsi_cmnd *sc)
 	conn = session->leadconn;
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (session->state == ISCSI_STATE_TERMINATE) {
 failed:
 		ISCSI_DBG_EH(session,
 			     "failing session reset: Could not log back into "
 			     "%s, %s [age %d]\n", session->targetname,
 			     conn->persistent_address, session->age);
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		mutex_unlock(&session->eh_mutex);
 		return FAILED;
 	}
 
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	mutex_unlock(&session->eh_mutex);
 	/*
 	 * we drop the lock here but the leadconn cannot be destoyed while
@@ -2355,14 +2378,14 @@ failed:
 		flush_signals(current);
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (session->state == ISCSI_STATE_LOGGED_IN) {
 		ISCSI_DBG_EH(session,
 			     "session reset succeeded for %s,%s\n",
 			     session->targetname, conn->persistent_address);
 	} else
 		goto failed;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	mutex_unlock(&session->eh_mutex);
 	return SUCCESS;
 }
@@ -2398,7 +2421,7 @@ int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 		     session->targetname);
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	/*
 	 * Just check if we are not logged in. We cannot check for
 	 * the phase because the reset could come from a ioctl.
@@ -2425,7 +2448,7 @@ int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 	case TMF_SUCCESS:
 		break;
 	case TMF_TIMEDOUT:
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
 		goto done;
 	default:
@@ -2434,21 +2457,21 @@ int iscsi_eh_target_reset(struct scsi_cmnd *sc)
 	}
 
 	rc = SUCCESS;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_suspend_tx(conn);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	memset(hdr, 0, sizeof(*hdr));
 	fail_scsi_tasks(conn, -1, DID_ERROR);
 	conn->tmf_state = TMF_INITIAL;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_start_tx(conn);
 	goto done;
 
 unlock:
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 done:
 	ISCSI_DBG_EH(session, "tgt %s reset result = %s\n", session->targetname,
 		     rc == SUCCESS ? "SUCCESS" : "FAILED");
@@ -2746,8 +2769,10 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
 	session->max_r2t = 1;
 	session->tt = iscsit;
 	session->dd_data = cls_session->dd_data + sizeof(*session);
+
 	mutex_init(&session->eh_mutex);
-	spin_lock_init(&session->lock);
+	spin_lock_init(&session->frwd_lock);
+	spin_lock_init(&session->back_lock);
 
 	/* initialize SCSI PDU commands pool */
 	if (iscsi_pool_init(&session->cmdpool, session->cmds_max,
@@ -2861,14 +2886,14 @@ iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size,
 	INIT_WORK(&conn->xmitwork, iscsi_xmitworker);
 
 	/* allocate login_task used for the login/text sequences */
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (!kfifo_out(&session->cmdpool.queue,
                          (void*)&conn->login_task,
 			 sizeof(void*))) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		goto login_task_alloc_fail;
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	data = (char *) __get_free_pages(GFP_KERNEL,
 					 get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
@@ -2905,7 +2930,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
 
 	del_timer_sync(&conn->transport_timer);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	conn->c_stage = ISCSI_CONN_CLEANUP_WAIT;
 	if (session->leadconn == conn) {
 		/*
@@ -2914,7 +2939,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
 		session->state = ISCSI_STATE_TERMINATE;
 		wake_up(&conn->ehwait);
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	/*
 	 * Block until all in-progress commands for this connection
@@ -2941,16 +2966,19 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
 	/* flush queued up work because we free the connection below */
 	iscsi_suspend_tx(conn);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	free_pages((unsigned long) conn->data,
 		   get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
 	kfree(conn->persistent_address);
 	kfree(conn->local_ipaddr);
+	/* regular RX path uses back_lock */
+	spin_lock_bh(&session->back_lock);
 	kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
 		    sizeof(void*));
+	spin_unlock_bh(&session->back_lock);
 	if (session->leadconn == conn)
 		session->leadconn = NULL;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_destroy_conn(cls_conn);
 }
@@ -2987,7 +3015,7 @@ int iscsi_conn_start(struct iscsi_cls_conn *cls_conn)
 		conn->ping_timeout = 5;
 	}
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	conn->c_stage = ISCSI_CONN_STARTED;
 	session->state = ISCSI_STATE_LOGGED_IN;
 	session->queued_cmdsn = session->cmdsn;
@@ -3016,7 +3044,7 @@ int iscsi_conn_start(struct iscsi_cls_conn *cls_conn)
 	default:
 		break;
 	}
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	iscsi_unblock_session(session->cls_session);
 	wake_up(&conn->ehwait);
@@ -3055,9 +3083,9 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
 	int old_stop_stage;
 
 	mutex_lock(&session->eh_mutex);
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (conn->stop_stage == STOP_CONN_TERM) {
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&session->frwd_lock);
 		mutex_unlock(&session->eh_mutex);
 		return;
 	}
@@ -3074,14 +3102,14 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
 
 	old_stop_stage = conn->stop_stage;
 	conn->stop_stage = flag;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	del_timer_sync(&conn->transport_timer);
 	iscsi_suspend_tx(conn);
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	conn->c_stage = ISCSI_CONN_STOPPED;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	/*
 	 * for connection level recovery we should not calculate
@@ -3102,11 +3130,11 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
 	/*
 	 * flush queues.
 	 */
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	fail_scsi_tasks(conn, -1, DID_TRANSPORT_DISRUPTED);
 	fail_mgmt_tasks(session, conn);
 	memset(&conn->tmhdr, 0, sizeof(conn->tmhdr));
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 	mutex_unlock(&session->eh_mutex);
 }
 
@@ -3133,10 +3161,10 @@ int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
 	struct iscsi_session *session = cls_session->dd_data;
 	struct iscsi_conn *conn = cls_conn->dd_data;
 
-	spin_lock_bh(&session->lock);
+	spin_lock_bh(&session->frwd_lock);
 	if (is_leading)
 		session->leadconn = conn;
-	spin_unlock_bh(&session->lock);
+	spin_unlock_bh(&session->frwd_lock);
 
 	/*
 	 * Unblock xmitworker(), Login Phase will pass through.
diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
index 2f738dddd078..60cb6dc3c6f0 100644
--- a/drivers/scsi/libiscsi_tcp.c
+++ b/drivers/scsi/libiscsi_tcp.c
@@ -446,7 +446,7 @@ iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
  * iscsi_tcp_cleanup_task - free tcp_task resources
  * @task: iscsi task
  *
- * must be called with session lock
+ * must be called with session back_lock
  */
 void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 {
@@ -457,6 +457,7 @@ void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 	if (!task->sc)
 		return;
 
+	spin_lock_bh(&tcp_task->queue2pool);
 	/* flush task's r2t queues */
 	while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
 		kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
@@ -470,6 +471,7 @@ void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 			    sizeof(void*));
 		tcp_task->r2t = NULL;
 	}
+	spin_unlock_bh(&tcp_task->queue2pool);
 }
 EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
 
@@ -577,11 +579,13 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
 		return ISCSI_ERR_DATALEN;
 	}
 
+	spin_lock(&tcp_task->pool2queue);
 	rc = kfifo_out(&tcp_task->r2tpool.queue, (void *)&r2t, sizeof(void *));
 	if (!rc) {
 		iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
 				  "Target has sent more R2Ts than it "
 				  "negotiated for or driver has leaked.\n");
+		spin_unlock(&tcp_task->pool2queue);
 		return ISCSI_ERR_PROTO;
 	}
 
@@ -596,6 +600,7 @@ static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
 	tcp_task->exp_datasn = r2tsn + 1;
 	kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
 	conn->r2t_pdus_cnt++;
+	spin_unlock(&tcp_task->pool2queue);
 
 	iscsi_requeue_task(task);
 	return 0;
@@ -668,14 +673,14 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 
 	switch(opcode) {
 	case ISCSI_OP_SCSI_DATA_IN:
-		spin_lock(&conn->session->lock);
+		spin_lock(&conn->session->back_lock);
 		task = iscsi_itt_to_ctask(conn, hdr->itt);
 		if (!task)
 			rc = ISCSI_ERR_BAD_ITT;
 		else
 			rc = iscsi_tcp_data_in(conn, task);
 		if (rc) {
-			spin_unlock(&conn->session->lock);
+			spin_unlock(&conn->session->back_lock);
 			break;
 		}
 
@@ -708,11 +713,11 @@ iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 						   tcp_conn->in.datalen,
 						   iscsi_tcp_process_data_in,
 						   rx_hash);
-			spin_unlock(&conn->session->lock);
+			spin_unlock(&conn->session->back_lock);
 			return rc;
 		}
 		rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
-		spin_unlock(&conn->session->lock);
+		spin_unlock(&conn->session->back_lock);
 		break;
 	case ISCSI_OP_SCSI_CMD_RSP:
 		if (tcp_conn->in.datalen) {
@@ -722,18 +727,20 @@ 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:
-		spin_lock(&conn->session->lock);
+		spin_lock(&conn->session->back_lock);
 		task = iscsi_itt_to_ctask(conn, hdr->itt);
+		spin_unlock(&conn->session->back_lock);
 		if (!task)
 			rc = ISCSI_ERR_BAD_ITT;
 		else if (ahslen)
 			rc = ISCSI_ERR_AHSLEN;
 		else if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
 			task->last_xfer = jiffies;
+			spin_lock(&conn->session->frwd_lock);
 			rc = iscsi_tcp_r2t_rsp(conn, task);
+			spin_unlock(&conn->session->frwd_lock);
 		} else
 			rc = ISCSI_ERR_PROTO;
-		spin_unlock(&conn->session->lock);
 		break;
 	case ISCSI_OP_LOGIN_RSP:
 	case ISCSI_OP_TEXT_RSP:
@@ -981,14 +988,13 @@ EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
 
 static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 {
-	struct iscsi_session *session = task->conn->session;
 	struct iscsi_tcp_task *tcp_task = task->dd_data;
 	struct iscsi_r2t_info *r2t = NULL;
 
 	if (iscsi_task_has_unsol_data(task))
 		r2t = &task->unsol_r2t;
 	else {
-		spin_lock_bh(&session->lock);
+		spin_lock_bh(&tcp_task->queue2pool);
 		if (tcp_task->r2t) {
 			r2t = tcp_task->r2t;
 			/* Continue with this R2T? */
@@ -1010,7 +1016,7 @@ static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 			else
 				r2t = tcp_task->r2t;
 		}
-		spin_unlock_bh(&session->lock);
+		spin_unlock_bh(&tcp_task->queue2pool);
 	}
 
 	return r2t;
@@ -1140,6 +1146,8 @@ int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
 			iscsi_pool_free(&tcp_task->r2tpool);
 			goto r2t_alloc_fail;
 		}
+		spin_lock_init(&tcp_task->pool2queue);
+		spin_lock_init(&tcp_task->queue2pool);
 	}
 
 	return 0;
diff --git a/drivers/scsi/qla4xxx/ql4_isr.c b/drivers/scsi/qla4xxx/ql4_isr.c
index bb34ef82b1d4..b1925d195f41 100644
--- a/drivers/scsi/qla4xxx/ql4_isr.c
+++ b/drivers/scsi/qla4xxx/ql4_isr.c
@@ -385,9 +385,9 @@ static void qla4xxx_passthru_status_entry(struct scsi_qla_host *ha,
 
 	cls_conn = ddb_entry->conn;
 	conn = cls_conn->dd_data;
-	spin_lock(&conn->session->lock);
+	spin_lock(&conn->session->back_lock);
 	task = iscsi_itt_to_task(conn, itt);
-	spin_unlock(&conn->session->lock);
+	spin_unlock(&conn->session->back_lock);
 
 	if (task == NULL) {
 		ql4_printk(KERN_ERR, ha, "%s: Task is NULL\n", __func__);
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 309f51336fb9..7221a24e821b 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -327,12 +327,19 @@ struct iscsi_session {
 	struct iscsi_transport	*tt;
 	struct Scsi_Host	*host;
 	struct iscsi_conn	*leadconn;	/* leading connection */
-	spinlock_t		lock;		/* protects session state, *
-						 * sequence numbers,       *
+	/* Between the forward and the backward locks exists a strict locking
+	 * hierarchy. The mutual exclusion zone protected by the forward lock
+	 * can enclose the mutual exclusion zone protected by the backward lock
+	 * but not vice versa.
+	 */
+	spinlock_t		frwd_lock;	/* protects session state, *
+						 * cmdsn, queued_cmdsn     *
 						 * session resources:      *
-						 * - cmdpool,		   *
-						 * - mgmtpool,		   *
-						 * - r2tpool		   */
+						 * - cmdpool kfifo_out ,   *
+						 * - mgmtpool,		   */
+	spinlock_t		back_lock;	/* protects cmdsn_exp      *
+						 * cmdsn_max,              *
+						 * cmdpool kfifo_in        */
 	int			state;		/* session state           */
 	int			age;		/* counts session re-opens */
 
diff --git a/include/scsi/libiscsi_tcp.h b/include/scsi/libiscsi_tcp.h
index 215469a9b801..2a7aa75dd009 100644
--- a/include/scsi/libiscsi_tcp.h
+++ b/include/scsi/libiscsi_tcp.h
@@ -83,6 +83,8 @@ struct iscsi_tcp_task {
 	struct iscsi_pool	r2tpool;
 	struct kfifo		r2tqueue;
 	void			*dd_data;
+	spinlock_t		pool2queue;
+	spinlock_t		queue2pool;
 };
 
 enum {