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python/machine: use socketpair() for console connections

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Create a socketpair for the console output. This should help eliminate
race conditions around console text early in the boot process that might
otherwise have been dropped on the floor before being able to connect to
QEMU under "server,nowait".

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20230928044943.849073-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
John Snow 2023-09-28 00:49:41 -04:00
parent 5f263cb1cc
commit 1d4796cd00
1 changed files with 27 additions and 3 deletions
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30
python/qemu/machine/machine.py
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@ -159,6 +159,8 @@ class QEMUMachine:
self._name = name or f"{id(self):x}"
self._sock_pair: Optional[Tuple[socket.socket, socket.socket]] = None
self._cons_sock_pair: Optional[
Tuple[socket.socket, socket.socket]] = None
self._temp_dir: Optional[str] = None
self._base_temp_dir = base_temp_dir
self._sock_dir = sock_dir
@ -316,8 +318,9 @@ class QEMUMachine:
for _ in range(self._console_index):
args.extend(['-serial', 'null'])
if self._console_set:
chardev = ('socket,id=console,path=%s,server=on,wait=off' %
self._console_address)
assert self._cons_sock_pair is not None
fd = self._cons_sock_pair[0].fileno()
chardev = f"socket,id=console,fd={fd}"
args.extend(['-chardev', chardev])
if self._console_device_type is None:
args.extend(['-serial', 'chardev:console'])
@ -352,6 +355,10 @@ class QEMUMachine:
nickname=self._name
)
if self._console_set:
self._cons_sock_pair = socket.socketpair()
os.set_inheritable(self._cons_sock_pair[0].fileno(), True)
# NOTE: Make sure any opened resources are *definitely* freed in
# _post_shutdown()!
# pylint: disable=consider-using-with
@ -369,6 +376,9 @@ class QEMUMachine:
def _post_launch(self) -> None:
if self._sock_pair:
self._sock_pair[0].close()
if self._cons_sock_pair:
self._cons_sock_pair[0].close()
if self._qmp_connection:
if self._sock_pair:
self._qmp.connect()
@ -524,6 +534,11 @@ class QEMUMachine:
self._console_socket.close()
self._console_socket = None
if self._cons_sock_pair:
self._cons_sock_pair[0].close()
self._cons_sock_pair[1].close()
self._cons_sock_pair = None
def _hard_shutdown(self) -> None:
"""
Perform early cleanup, kill the VM, and wait for it to terminate.
@ -885,10 +900,19 @@ class QEMUMachine:
"""
if self._console_socket is None:
LOG.debug("Opening console socket")
if not self._console_set:
raise QEMUMachineError(
"Attempt to access console socket with no connection")
assert self._cons_sock_pair is not None
# os.dup() is used here for sock_fd because otherwise we'd
# have two rich python socket objects that would each try to
# close the same underlying fd when either one gets garbage
# collected.
self._console_socket = console_socket.ConsoleSocket(
self._console_address,
sock_fd=os.dup(self._cons_sock_pair[1].fileno()),
file=self._console_log_path,
drain=self._drain_console)
self._cons_sock_pair[1].close()
return self._console_socket
@property