logind: if we have to stop a session, kill at least its leader

src/login/logind-session.c

@@ -601,6 +601,23 @@ static int session_terminate_cgroup(Session *s) {
                         log_error("Failed to kill session cgroup: %s", strerror(-r));
 
         } else {
+                if (s->leader > 0) {
+                        Session *t;
+
+                        /* We still send a HUP to the leader process,
+                         * even if we are not supposed to kill the
+                         * whole cgroup. But let's first check the
+                         * leader still exists and belongs to our
+                         * session... */
+
+                        r = manager_get_session_by_pid(s->manager, s->leader, &t);
+                        if (r > 0 && t == s) {
+                                kill(s->leader, SIGTERM); /* for normal processes */
+                                kill(s->leader, SIGHUP);  /* for shells */
+                                kill(s->leader, SIGCONT); /* in case they are stopped */
+                        }
+                }
+
                 r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path, true);
                 if (r < 0)
                         log_error("Failed to check session cgroup: %s", strerror(-r));
@@ -608,8 +625,7 @@ static int session_terminate_cgroup(Session *s) {
                         r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, s->cgroup_path);
                         if (r < 0)
                                 log_error("Failed to delete session cgroup: %s", strerror(-r));
-                } else
+                }
-                        r = -EBUSY;
         }
 
         STRV_FOREACH(k, s->user->manager->controllers)
@@ -620,7 +636,7 @@ static int session_terminate_cgroup(Session *s) {
         free(s->cgroup_path);
         s->cgroup_path = NULL;
 
-        return r;
+        return 0;
 }
 
 static int session_unlink_x11_socket(Session *s) {

src/login/logind.c

@@ -781,34 +781,68 @@ finish:
         return r;
 }
 
-void manager_cgroup_notify_empty(Manager *m, const char *cgroup) {
+int manager_get_session_by_cgroup(Manager *m, const char *cgroup, Session **session) {
-        Session *s;
         char *p;
 
         assert(m);
         assert(cgroup);
+        assert(session);
 
         p = strdup(cgroup);
         if (!p) {
                 log_error("Out of memory.");
-                return;
+                return -ENOMEM;
         }
 
         for (;;) {
+                Session *s;
                 char *e;
 
-                if (isempty(p) || streq(p, "/"))
+                if (isempty(p) || streq(p, "/")) {
-                        break;
+                        free(p);
+                        *session = NULL;
+                        return 0;
+                }
 
                 s = hashmap_get(m->cgroups, p);
-                if (s)
+                if (s) {
-                        session_add_to_gc_queue(s);
+                        free(p);
+                        *session = s;
+                        return 1;
+                }
 
                 assert_se(e = strrchr(p, '/'));
                 *e = 0;
         }
+}
 
+int manager_get_session_by_pid(Manager *m, pid_t pid, Session **session) {
+        char *p;
+        int r;
+
+        assert(m);
+        assert(pid >= 1);
+        assert(session);
+
+        r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, pid, &p);
+        if (r < 0)
+                return r;
+
+        r = manager_get_session_by_cgroup(m, p, session);
         free(p);
+
+        return r;
+}
+
+void manager_cgroup_notify_empty(Manager *m, const char *cgroup) {
+        Session *s;
+        int r;
+
+        r = manager_get_session_by_cgroup(m, cgroup, &s);
+        if (r <= 0)
+                return;
+
+        session_add_to_gc_queue(s);
 }
 
 static void manager_pipe_notify_eof(Manager *m, int fd) {

src/login/logind.h

@@ -116,6 +116,9 @@ void manager_gc(Manager *m, bool drop_not_started);
 
 int manager_get_idle_hint(Manager *m, dual_timestamp *t);
 
+int manager_get_session_by_cgroup(Manager *m, const char *cgroup, Session **session);
+int manager_get_session_by_pid(Manager *m, pid_t pid, Session **session);
+
 extern const DBusObjectPathVTable bus_manager_vtable;
 
 DBusHandlerResult bus_message_filter(DBusConnection *c, DBusMessage *message, void *userdata);