iser-target: Fix session hang in case of an rdma read DIF error

commit 364189f0 upstream.

This hang was a result of a missing command put when
a DIF error occurred during a rdma read (and we sent
an CHECK_CONDITION error without passing it to the
backend).
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -1861,11 +1861,13 @@ isert_completion_rdma_read(struct iser_tx_desc *tx_desc,
 	cmd->i_state = ISTATE_RECEIVED_LAST_DATAOUT;
 	spin_unlock_bh(&cmd->istate_lock);
 
-	if (ret)
+	if (ret) {
+		target_put_sess_cmd(se_cmd->se_sess, se_cmd);
 		transport_send_check_condition_and_sense(se_cmd,
 							 se_cmd->pi_err, 0);
-	else
+	} else {
 		target_execute_cmd(se_cmd);
+	}
 }
 
 static void