From: Joachim Falk <joachim.falk@gmx.de>

The virNetDaemonQuit(dmn) command in virLXCControllerSignalChildIO triggers an
early close of all clients of lxc_controller. Here, libvirtd itself is a client
of this controller, and the client connection is used to notify libvirtd if a
reboot of the container is required. However, the client connection was closed
before such a status could be sent to libvirtd. To fix this bug, we will
immediately send the reboot or shutdown status of the container to libvirtd,
and only after client disconnect will we trigger virNetDaemonQuit.

Fixes: #237
Bug: https://gitlab.com/libvirt/libvirt/-/issues/237
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991773
Signed-off-by: Joachim Falk <joachim.falk@gmx.de>
---
 src/lxc/lxc_controller.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
index 444f728af4..039efcd7c7 100644
--- a/src/lxc/lxc_controller.c
+++ b/src/lxc/lxc_controller.c
@@ -894,8 +894,10 @@ static void virLXCControllerClientCloseHook(virNetServerClient *client)
     virLXCController *ctrl = virNetServerClientGetPrivateData(client);
 
     VIR_DEBUG("Client %p has closed", client);
-    if (ctrl->client == client)
+    if (ctrl->client == client) {
         ctrl->client = NULL;
+        VIR_DEBUG("Client has gone away");
+    }
     if (ctrl->inShutdown) {
         VIR_DEBUG("Arm timer to quit event loop");
         virEventUpdateTimeout(ctrl->timerShutdown, 0);
@@ -1006,8 +1008,11 @@ static int lxcControllerClearCapabilities(void)
 static bool wantReboot;
 static virMutex lock = VIR_MUTEX_INITIALIZER;
 
+static int
+virLXCControllerEventSendExit(virLXCController *ctrl,
+                              int exitstatus);
 
-static void virLXCControllerSignalChildIO(virNetDaemon *dmn,
+static void virLXCControllerSignalChildIO(virNetDaemon *dmn G_GNUC_UNUSED,
                                           siginfo_t *info G_GNUC_UNUSED,
                                           void *opaque)
 {
@@ -1018,7 +1023,6 @@ static void virLXCControllerSignalChildIO(virNetDaemon *dmn,
     ret = waitpid(-1, &status, WNOHANG);
     VIR_DEBUG("Got sig child %d vs %lld", ret, (long long)ctrl->initpid);
     if (ret == ctrl->initpid) {
-        virNetDaemonQuit(dmn);
         virMutexLock(&lock);
         if (WIFSIGNALED(status) &&
             WTERMSIG(status) == SIGHUP) {
@@ -1026,6 +1030,7 @@ static void virLXCControllerSignalChildIO(virNetDaemon *dmn,
             wantReboot = true;
         }
         virMutexUnlock(&lock);
+        virLXCControllerEventSendExit(ctrl, wantReboot ? 1 : 0);
     }
 }
 
@@ -2276,9 +2281,10 @@ virLXCControllerEventSendExit(virLXCController *ctrl,
         VIR_DEBUG("Waiting for client to complete dispatch");
         ctrl->inShutdown = true;
         virNetServerClientDelayedClose(ctrl->client);
-        virNetDaemonRun(ctrl->daemon);
+    } else {
+        VIR_DEBUG("Arm timer to quit event loop");
+        virEventUpdateTimeout(ctrl->timerShutdown, 0);
     }
-    VIR_DEBUG("Client has gone away");
     return 0;
 }
 
@@ -2430,8 +2436,6 @@ virLXCControllerRun(virLXCController *ctrl)
 
     rc = virLXCControllerMain(ctrl);
 
-    virLXCControllerEventSendExit(ctrl, rc);
-
  cleanup:
     VIR_FORCE_CLOSE(control[0]);
     VIR_FORCE_CLOSE(control[1]);
-- 
2.30.2

On 12/2/21 19:56, joachim.falk@jfalk.de wrote:
> From: Joachim Falk <joachim.falk@gmx.de>
> 
> The virNetDaemonQuit(dmn) command in virLXCControllerSignalChildIO triggers an
> early close of all clients of lxc_controller. Here, libvirtd itself is a client
> of this controller, and the client connection is used to notify libvirtd if a
> reboot of the container is required. However, the client connection was closed
> before such a status could be sent to libvirtd. To fix this bug, we will
> immediately send the reboot or shutdown status of the container to libvirtd,
> and only after client disconnect will we trigger virNetDaemonQuit.
> 
> Fixes: #237
> Bug: https://gitlab.com/libvirt/libvirt/-/issues/237
> Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=991773
> Signed-off-by: Joachim Falk <joachim.falk@gmx.de>
> ---
>  src/lxc/lxc_controller.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

and pushed. Congratulations on your first libvirt contribution!

Michal