examples/discovery-loop.py: update to use tcp transport

Update the discovery-loop.py example to use the tcp transport and
fix an issue where the controller wasn't disconnected when the
disovery failed.

Signed-off-by: Hannes Reinecke <hare@suse.de>

Author: hreinecke

examples/discover-loop.py

@@ -2,19 +2,6 @@
 # SPDX-License-Identifier: Apache-2.0
 '''
 Example script for nvme discovery
-
-Copyright (c) 2021 Hannes Reinecke, SUSE Software Solutions
-Licensed under the Apache License, Version 2.0 (the "License"); you may
-not use this file except in compliance with the License. You may obtain
-a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-License for the specific language governing permissions and limitations
-under the License.
 '''
 
 import sys
@@ -29,17 +16,24 @@ def disc_supp_str(dlp_supp_opts):
     }
     return [txt for msk, txt in d.items() if dlp_supp_opts & msk]
 
-r = nvme.root()
-h = nvme.host(r)
-c = nvme.ctrl(r, nvme.NVME_DISC_SUBSYS_NAME, 'loop')
+root = nvme.root()
+host = nvme.host(root)
+
+subsysnqn = nvme.NVME_DISC_SUBSYS_NAME
+transport = 'tcp'
+traddr = '127.0.0.1'
+trsvcid = '4420'
+
+ctrl = nvme.ctrl(root, subsysnqn=subsysnqn, transport=transport, traddr=traddr, trsvcid=trsvcid)
+
 try:
-    c.connect(h)
+    ctrl.connect(host)
 except Exception as e:
     sys.exit(f'Failed to connect: {e}')
 
-print("connected to %s subsys %s" % (c.name, c.subsystem.name))
+print(f'{ctrl.name} connected to subsys {ctrl.subsystem}')
 
-slp = c.supported_log_pages()
+slp = ctrl.supported_log_pages()
 
 try:
     dlp_supp_opts = slp[nvme.NVME_LOG_LID_DISCOVER] >> 16
@@ -50,16 +44,20 @@ def disc_supp_str(dlp_supp_opts):
 
 try:
     lsp = nvme.NVMF_LOG_DISC_LSP_PLEO if dlp_supp_opts & nvme.NVMF_LOG_DISC_LID_PLEOS else 0
-    d = c.discover(lsp=lsp)
-    print(pprint.pformat(d))
+    disc_log = ctrl.discover(lsp=lsp)
 except Exception as e:
     sys.exit(f'Failed to discover: {e}')
+    disc_log = []
+    pass
+
+for dlpe in disc_log:
+    print(f'log entry {dlpe["portid"]}: {dlpe["subtype"]} {dlpe["subnqn"]}')
 
 try:
-    c.disconnect()
+    ctrl.disconnect()
 except Exception as e:
     sys.exit(f'Failed to disconnect: {e}')
 
-c = None
-h = None
-r = None
+for s in host.subsystems():
+    for c in s.controllers():
+        print(f'{s}: {c.name}')