Make core.shutdown() reentrant and remove monitor state guard

Make Core.shutdown() reentrant using an asyncio.Event so that
concurrent callers await the in-progress shutdown instead of
starting a second one. This ensures the inhibitor lock is held
until shutdown truly completes, even if PrepareForShutdown fires
while an API-initiated shutdown is already in progress.

The state guard in the monitor task is no longer needed since
core.shutdown() now handles reentrance itself.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

supervisor/core.py

@@ -42,6 +42,7 @@ class Core(CoreSysAttributes):
         self.coresys: CoreSys = coresys
         self._state: CoreState = CoreState.INITIALIZE
         self.exit_code: int = 0
+        self._shutdown_event: asyncio.Event = asyncio.Event()
 
     @property
     def state(self) -> CoreState:
@@ -353,28 +354,39 @@ class Core(CoreSysAttributes):
         self.sys_loop.stop()
 
     async def shutdown(self, *, remove_homeassistant_container: bool = False) -> None:
-        """Shutdown all running containers in correct order."""
+        """Shutdown all running containers in correct order.
+
+        Reentrant: if a shutdown is already in progress, subsequent calls
+        await completion of the existing shutdown rather than starting a second one.
+        """
+        if self.state in (CoreState.SHUTDOWN, CoreState.STOPPING, CoreState.CLOSE):
+            await self._shutdown_event.wait()
+            return
+
         # don't process scheduler anymore
         if self.state == CoreState.RUNNING:
             await self.set_state(CoreState.SHUTDOWN)
 
-        # Shutdown Application Add-ons, using Home Assistant API
-        await self.sys_addons.shutdown(AddonStartup.APPLICATION)
+        try:
+            # Shutdown Application Add-ons, using Home Assistant API
+            await self.sys_addons.shutdown(AddonStartup.APPLICATION)
 
-        # Close Home Assistant
-        with suppress(HassioError):
-            await self.sys_homeassistant.core.stop(
-                remove_container=remove_homeassistant_container
-            )
+            # Close Home Assistant
+            with suppress(HassioError):
+                await self.sys_homeassistant.core.stop(
+                    remove_container=remove_homeassistant_container
+                )
 
-        # Shutdown System Add-ons
-        await self.sys_addons.shutdown(AddonStartup.SERVICES)
-        await self.sys_addons.shutdown(AddonStartup.SYSTEM)
-        await self.sys_addons.shutdown(AddonStartup.INITIALIZE)
+            # Shutdown System Add-ons
+            await self.sys_addons.shutdown(AddonStartup.SERVICES)
+            await self.sys_addons.shutdown(AddonStartup.SYSTEM)
+            await self.sys_addons.shutdown(AddonStartup.INITIALIZE)
 
-        # Shutdown all Plugins
-        if self.state in (CoreState.STOPPING, CoreState.SHUTDOWN):
-            await self.sys_plugins.shutdown()
+            # Shutdown all Plugins
+            if self.state in (CoreState.STOPPING, CoreState.SHUTDOWN):
+                await self.sys_plugins.shutdown()
+        finally:
+            self._shutdown_event.set()
 
     async def _update_last_boot(self) -> None:
         """Update last boot time."""

supervisor/host/manager.py

@@ -9,7 +9,7 @@ from typing import Self
 
 from awesomeversion import AwesomeVersion
 
-from ..const import BusEvent, CoreState
+from ..const import BusEvent
 from ..coresys import CoreSys, CoreSysAttributes
 from ..exceptions import (
     DBusError,
@@ -233,14 +233,6 @@ class HostManager(CoreSysAttributes):
                     if not active:
                         continue
 
-                    # Only handle if Supervisor didn't initiate the shutdown
-                    if self.sys_core.state != CoreState.RUNNING:
-                        _LOGGER.debug(
-                            "PrepareForShutdown received but already in state %s",
-                            self.sys_core.state,
-                        )
-                        break
-
                     _LOGGER.info(
                         "Host shutdown/reboot detected, gracefully stopping services"
                     )

tests/host/test_manager.py

@@ -1,7 +1,7 @@
 """Test host manager."""
 
 import asyncio
-from unittest.mock import AsyncMock, patch
+from unittest.mock import patch
 
 from awesomeversion import AwesomeVersion
 import pytest
@@ -109,22 +109,25 @@ async def test_host_shutdown_on_prepare_for_shutdown_signal(
             await shutdown_called.wait()
 
 
-async def test_host_shutdown_signal_ignored_when_not_running(
+async def test_host_shutdown_signal_reentrant(
     coresys: CoreSys, logind_service: LogindService
 ):
-    """Test PrepareForShutdown is ignored if Supervisor already shutting down."""
+    """Test PrepareForShutdown during in-progress shutdown awaits same shutdown."""
+    shutdown_called = asyncio.Event()
+
+    async def mock_shutdown(**kwargs):
+        shutdown_called.set()
+
     await coresys.host.load()
     await coresys.core.set_state(CoreState.SHUTDOWN)
 
     # Give the monitor task time to start and register the signal listener
     await asyncio.sleep(0.1)
 
-    with patch.object(
-        coresys.core, "shutdown", new_callable=AsyncMock
-    ) as mock_shutdown:
+    with patch.object(coresys.core, "shutdown", side_effect=mock_shutdown):
         logind_service.PrepareForShutdown()
         await logind_service.ping()
-        # Give the monitor task time to process the signal
-        await asyncio.sleep(0.1)
 
-        mock_shutdown.assert_not_called()
+        # shutdown() is called reentrantly - it awaits the in-progress shutdown
+        async with asyncio.timeout(2):
+            await shutdown_called.wait()