Re: [PATCH] remote_daemon: Don't run virStateCleanup() if virStateReload() is still running

When a SIGHUP is received a thread is spawned that runs virStateReload(). However, if SIGINT is received while the former thread is still running then we may get into problematic situation: the cleanup code in main() sees drivers initialized and thus calls virStateCleanup(). So now we have two threads, one running virStateReload() the other virStateCleanup(). In this situation it's very likely that a race condition occurs and either of threads causes SIGSEGV. To fix this, unmark drivers as initialized in the virStateReload() thread for the time the function runs. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2075837 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/remote/remote_daemon.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/src/remote/remote_daemon.c b/src/remote/remote_daemon.c index 26469e0d9f..37d27f93f4 100644 --- a/src/remote/remote_daemon.c +++ b/src/remote/remote_daemon.c @@ -77,7 +77,7 @@ virNetSASLContext *saslCtxt = NULL; virNetServerProgram *remoteProgram = NULL; virNetServerProgram *qemuProgram = NULL; -volatile bool driversInitialized = false; +volatile gint driversInitialized = 0; static void daemonErrorHandler(void *opaque G_GNUC_UNUSED, virErrorPtr err G_GNUC_UNUSED) @@ -453,8 +453,13 @@ static void daemonReloadHandlerThread(void *opaque G_GNUC_UNUSED) VIR_INFO("Reloading configuration on SIGHUP"); virHookCall(VIR_HOOK_DRIVER_DAEMON, "-", VIR_HOOK_DAEMON_OP_RELOAD, SIGHUP, "SIGHUP", NULL, NULL); - if (virStateReload() < 0) + + g_atomic_int_set(&driversInitialized, 0);

+ if (virStateReload() < 0) { VIR_WARN("Error while reloading drivers");

+ } else { + g_atomic_int_inc(&driversInitialized); + } } static void daemonReloadHandler(virNetDaemon *dmn G_GNUC_UNUSED, @@ -463,7 +468,7 @@ static void daemonReloadHandler(virNetDaemon *dmn G_GNUC_UNUSED, { virThread thr; - if (!driversInitialized) { + if (g_atomic_int_get(&driversInitialized) == 0) {

VIR_WARN("Drivers are not initialized, reload ignored"); return; } @@ -607,7 +612,7 @@ static void daemonRunStateInit(void *opaque) goto cleanup; } - driversInitialized = true; + g_atomic_int_inc(&driversInitialized); virNetDaemonSetShutdownCallbacks(dmn, virStateShutdownPrepare, @@ -1212,10 +1217,10 @@ int main(int argc, char **argv) { cleanup: virNetlinkEventServiceStopAll(); - if (driversInitialized) { + if (g_atomic_int_get(&driversInitialized) != 0) { /* NB: Possible issue with timing window between driversInitialized * setting if virNetlinkEventServerStart fails */ - driversInitialized = false; + g_atomic_int_set(&driversInitialized, 0); virStateCleanup(); } -- 2.35.1