python: support pylint 2.16

Pylint 2.16 adds a few new checks that cause the optional check-tox CI
job to fail.

1. The superfluous-parens check seems to be a bit more aggressive,
2. broad-exception-raised is new; it discourages "raise Exception".

Fix these minor issues and turn the lights green.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Beraldo Leal <bleal@redhat.com>
Message-id: 20230210003147.1309376-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/qemu/qmp/protocol.py

@@ -207,7 +207,7 @@ class AsyncProtocol(Generic[T]):
     logger = logging.getLogger(__name__)
 
     # Maximum allowable size of read buffer
-    _limit = (64 * 1024)
+    _limit = 64 * 1024
 
     # -------------------------
     # Section: Public interface

python/qemu/qmp/qmp_client.py

@@ -198,7 +198,7 @@ class QMPClient(AsyncProtocol[Message], Events):
     logger = logging.getLogger(__name__)
 
     # Read buffer limit; 10MB like libvirt default
-    _limit = (10 * 1024 * 1024)
+    _limit = 10 * 1024 * 1024
 
     # Type alias for pending execute() result items
     _PendingT = Union[Message, ExecInterruptedError]

python/qemu/utils/qemu_ga_client.py

@@ -155,7 +155,7 @@ class QemuGuestAgentClient:
 
     def fsfreeze(self, cmd: str) -> object:
         if cmd not in ['status', 'freeze', 'thaw']:
-            raise Exception('Invalid command: ' + cmd)
+            raise ValueError('Invalid command: ' + cmd)
         # Can be int (freeze, thaw) or GuestFsfreezeStatus (status)
         return getattr(self.qga, 'fsfreeze' + '_' + cmd)()
 
@@ -167,7 +167,7 @@ class QemuGuestAgentClient:
 
     def suspend(self, mode: str) -> None:
         if mode not in ['disk', 'ram', 'hybrid']:
-            raise Exception('Invalid mode: ' + mode)
+            raise ValueError('Invalid mode: ' + mode)
 
         try:
             getattr(self.qga, 'suspend' + '_' + mode)()
@@ -178,7 +178,7 @@ class QemuGuestAgentClient:
 
     def shutdown(self, mode: str = 'powerdown') -> None:
         if mode not in ['powerdown', 'halt', 'reboot']:
-            raise Exception('Invalid mode: ' + mode)
+            raise ValueError('Invalid mode: ' + mode)
 
         try:
             self.qga.shutdown(mode=mode)