iser-target: remove command with state ISTATE_REMOVE

As documented in iscsit_sequence_cmd:
/*
 * Existing callers for iscsit_sequence_cmd() will silently
 * ignore commands with CMDSN_LOWER_THAN_EXP, so force this
 * return for CMDSN_MAXCMDSN_OVERRUN as well..
 */

We need to silently finish a command when it's in ISTATE_REMOVE.
This fixes an teardown hang we were seeing where a mis-behaved
initiator (triggered by allocation error injections) sent us a
cmdsn which was lower than expected.

Signed-off-by: Jenny Derzhavetz <jennyf@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -2999,9 +2999,16 @@ isert_get_dataout(struct iscsi_conn *conn, struct iscsi_cmd *cmd, bool recovery)
 static int
 isert_immediate_queue(struct iscsi_conn *conn, struct iscsi_cmd *cmd, int state)
 {
-	int ret;
+	struct isert_cmd *isert_cmd = iscsit_priv_cmd(cmd);
+	int ret = 0;
 
 	switch (state) {
+	case ISTATE_REMOVE:
+		spin_lock_bh(&conn->cmd_lock);
+		list_del_init(&cmd->i_conn_node);
+		spin_unlock_bh(&conn->cmd_lock);
+		isert_put_cmd(isert_cmd, true);
+		break;
 	case ISTATE_SEND_NOPIN_WANT_RESPONSE:
 		ret = isert_put_nopin(cmd, conn, false);
 		break;