iscsi-target: Fix ISCSI_OP_SCSI_TMFUNC handling for iser

This patch adds target_get_sess_cmd reference counting for
iscsit_handle_task_mgt_cmd(), and adds a target_put_sess_cmd()
for the failure case.

It also fixes a bug where ISCSI_OP_SCSI_TMFUNC type commands
where leaking iscsi_cmd->i_conn_node and eventually triggering
an OOPs during struct isert_conn shutdown.

Cc: stable@vger.kernel.org  # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index 7e219a4..9efbf13 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -1200,14 +1200,12 @@
 {
 	struct iscsi_cmd *cmd = &isert_cmd->iscsi_cmd;
 	struct isert_conn *isert_conn = isert_cmd->conn;
-	struct iscsi_conn *conn;
+	struct iscsi_conn *conn = isert_conn->conn;
 
 	pr_debug("Entering isert_put_cmd: %p\n", isert_cmd);
 
 	switch (cmd->iscsi_opcode) {
 	case ISCSI_OP_SCSI_CMD:
-		conn = isert_conn->conn;
-
 		spin_lock_bh(&conn->cmd_lock);
 		if (!list_empty(&cmd->i_conn_node))
 			list_del(&cmd->i_conn_node);
@@ -1217,16 +1215,18 @@
 			iscsit_stop_dataout_timer(cmd);
 
 		isert_unmap_cmd(isert_cmd, isert_conn);
-		/*
-		 * Fall-through
-		 */
+		transport_generic_free_cmd(&cmd->se_cmd, 0);
+		break;
 	case ISCSI_OP_SCSI_TMFUNC:
+		spin_lock_bh(&conn->cmd_lock);
+		if (!list_empty(&cmd->i_conn_node))
+			list_del(&cmd->i_conn_node);
+		spin_unlock_bh(&conn->cmd_lock);
+
 		transport_generic_free_cmd(&cmd->se_cmd, 0);
 		break;
 	case ISCSI_OP_REJECT:
 	case ISCSI_OP_NOOP_OUT:
-		conn = isert_conn->conn;
-
 		spin_lock_bh(&conn->cmd_lock);
 		if (!list_empty(&cmd->i_conn_node))
 			list_del(&cmd->i_conn_node);