fixup! [LibOS] Delay IPC leader notification until it has 0 connections

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

libos/src/ipc/libos_ipc_worker.c

@@ -65,7 +65,7 @@ static ipc_callback ipc_callbacks[] = {
     [IPC_MSG_FILE_LOCK_CLEAR_PID] = ipc_file_lock_clear_pid_callback,
 };
 
-static PAL_HANDLE leader_notifier;
+static PAL_HANDLE g_leader_notifier;
 
 static void ipc_leader_died_callback(void) {
     /* This might happen legitimately e.g. if IPC leader is also our parent and does `wait` + `exit`
@@ -74,7 +74,7 @@ static void ipc_leader_died_callback(void) {
     log_debug("IPC leader disconnected");
 }
 
-static inline int is_ipc_leader(void) {
+static inline bool is_ipc_leader(void) {
     return g_process_ipc_ids.self_vmid == STARTING_VMID;
 }
 
@@ -112,17 +112,17 @@ static int add_ipc_connection(PAL_HANDLE handle, IDTYPE id) {
     return 0;
 }
 
-static void del_ipc_connection(struct libos_ipc_connection* conn,
-                               PAL_HANDLE* notifier) {
+static void del_ipc_connection(struct libos_ipc_connection* conn) {
     LISTP_DEL(conn, &g_ipc_connections, list);
     g_ipc_connections_cnt--;
 
     PalObjectDestroy(conn->handle);
 
     free(conn);
 
-    if (notifier && g_ipc_connections_cnt == 0)
-        PalEventSet(*notifier);
+    if (is_ipc_leader() && g_ipc_connections_cnt == 0) {
+        PalEventSet(g_leader_notifier);
+    }
 }
 
 /*
@@ -223,7 +223,7 @@ static int receive_ipc_messages(struct libos_ipc_connection* conn) {
     return 0;
 }
 
-static noreturn void ipc_worker_main(PAL_HANDLE* notifier) {
+static noreturn void ipc_worker_main(void) {
     /* TODO: If we had a global array of connections (instead of a list) we wouldn't have to gather
      * them all here in every loop iteration, but then deletion would be slower (but deletion should
      * be rare). */
@@ -347,7 +347,7 @@ static noreturn void ipc_worker_main(PAL_HANDLE* notifier) {
                 if (ret == 1) {
                     /* Connection closed. */
                     disconnect_callbacks(conn);
-                    del_ipc_connection(conn, notifier);
+                    del_ipc_connection(conn);
                     continue;
                 }
                 if (ret < 0) {
@@ -361,17 +361,12 @@ static noreturn void ipc_worker_main(PAL_HANDLE* notifier) {
              * more time - in case there are messages left to be read. */
             if (ret_events[i] == PAL_WAIT_ERROR) {
                 disconnect_callbacks(conn);
-                del_ipc_connection(conn, notifier);
+                del_ipc_connection(conn);
             }
         }
     }
 
 out_die:
-    if (notifier) {
-        g_ipc_connections_cnt = 0;
-        PalEventSet(*notifier);
-    }
-
     PalProcessExit(1);
 }
 
@@ -386,8 +381,7 @@ static int ipc_worker_wrapper(void* arg) {
 
     log_debug("IPC worker started");
 
-    PAL_HANDLE* notifier = is_ipc_leader() ? &leader_notifier : NULL;
-    ipc_worker_main(notifier);
+    ipc_worker_main();
     /* Unreachable. */
 }
 
@@ -405,9 +399,9 @@ static int create_ipc_worker(void) {
 
     /* IPC leader gets a notifier used in terminate_ipc_leader */
     if (is_ipc_leader() &&
-        PalEventCreate(&leader_notifier, false, false) < 0) {
+        (ret = PalEventCreate(&g_leader_notifier, /*init_signaled=*/false, /*auto_clear=*/false)) < 0) {
         log_error("IPC leader: PalEventCreate() failed");
-        return -ENOMEM;
+        return pal_to_unix_errno(ret);;
     }
 
     g_worker_thread = get_new_internal_thread();
@@ -434,9 +428,9 @@ int init_ipc_worker(void) {
 
 void terminate_ipc_worker(void) {
     if (is_ipc_leader()) {
-        PalEventClear(leader_notifier);
+        PalEventClear(g_leader_notifier);
         while (__atomic_load_n(&g_ipc_connections_cnt, __ATOMIC_ACQUIRE) > 0 &&
-               PalEventWait(leader_notifier, NULL) < 0);
+               PalEventWait(g_leader_notifier, NULL) < 0);
     }
     set_pollable_event(&g_worker_thread->pollable_event);