service: watch main pid even in final states

In some circumstances, for example when start-up times out we
immediately jump into the final state, at which point we still should
try to watch the main pid so that the SIGCHLD allows us to quickly
move into dead state.

3 files changed, 60 insertions, 48 deletions

diff --git a/src/core/service.c b/src/core/service.c
index 67cf63099a..fa47061938 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -1488,7 +1488,8 @@ static void service_set_state(Service *s, ServiceState state) {
         if (!IN_SET(state,
                     SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST,
                     SERVICE_RELOAD,
-                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL, SERVICE_STOP_POST,
+                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                    SERVICE_STOP_POST,
                     SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL,
                     SERVICE_AUTO_RESTART))
                 s->timer_event_source = sd_event_source_unref(s->timer_event_source);
@@ -1496,7 +1497,9 @@ static void service_set_state(Service *s, ServiceState state) {
         if (!IN_SET(state,
                     SERVICE_START, SERVICE_START_POST,
                     SERVICE_RUNNING, SERVICE_RELOAD,
-                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL)) {
+                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                    SERVICE_STOP_POST,
+                    SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL)) {
                 service_unwatch_main_pid(s);
                 s->main_command = NULL;
         }
@@ -1504,7 +1507,8 @@ static void service_set_state(Service *s, ServiceState state) {
         if (!IN_SET(state,
                     SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST,
                     SERVICE_RELOAD,
-                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL, SERVICE_STOP_POST,
+                    SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                    SERVICE_STOP_POST,
                     SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL)) {
                 service_unwatch_control_pid(s);
                 s->control_command = NULL;
@@ -1561,22 +1565,16 @@ static int service_coldplug(Unit *u) {
 
         if (s->deserialized_state != s->state) {
 
-                if (s->deserialized_state == SERVICE_START_PRE ||
-                    s->deserialized_state == SERVICE_START ||
-                    s->deserialized_state == SERVICE_START_POST ||
-                    s->deserialized_state == SERVICE_RELOAD ||
-                    s->deserialized_state == SERVICE_STOP ||
-                    s->deserialized_state == SERVICE_STOP_SIGTERM ||
-                    s->deserialized_state == SERVICE_STOP_SIGKILL ||
-                    s->deserialized_state == SERVICE_STOP_POST ||
-                    s->deserialized_state == SERVICE_FINAL_SIGTERM ||
-                    s->deserialized_state == SERVICE_FINAL_SIGKILL) {
+                if (IN_SET(s->deserialized_state,
+                           SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST,
+                           SERVICE_RELOAD,
+                           SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                           SERVICE_STOP_POST,
+                           SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL)) {
 
                         usec_t k;
 
-                        k = s->deserialized_state == SERVICE_START_PRE || s->deserialized_state == SERVICE_START ||
-                                s->deserialized_state == SERVICE_START_POST || s->deserialized_state == SERVICE_RELOAD ?
-                                s->timeout_start_usec : s->timeout_stop_usec;
+                        k = IN_SET(s->deserialized_state, SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST, SERVICE_RELOAD) ? s->timeout_start_usec : s->timeout_stop_usec;
 
                         /* For the start/stop timeouts 0 means off */
                         if (k > 0) {
@@ -1594,38 +1592,30 @@ static int service_coldplug(Unit *u) {
                                 return r;
                 }
 
-                if ((s->deserialized_state == SERVICE_START &&
-                     (s->type == SERVICE_FORKING ||
-                      s->type == SERVICE_DBUS ||
-                      s->type == SERVICE_ONESHOT ||
-                      s->type == SERVICE_NOTIFY)) ||
-                    s->deserialized_state == SERVICE_START_POST ||
-                    s->deserialized_state == SERVICE_RUNNING ||
-                    s->deserialized_state == SERVICE_RELOAD ||
-                    s->deserialized_state == SERVICE_STOP ||
-                    s->deserialized_state == SERVICE_STOP_SIGTERM ||
-                    s->deserialized_state == SERVICE_STOP_SIGKILL)
-                        if (s->main_pid > 0) {
-                                r = unit_watch_pid(UNIT(s), s->main_pid);
-                                if (r < 0)
-                                        return r;
-                        }
+                if (pid_valid(s->main_pid) &&
+                    ((s->deserialized_state == SERVICE_START && IN_SET(s->type, SERVICE_FORKING, SERVICE_DBUS, SERVICE_ONESHOT, SERVICE_NOTIFY)) ||
+                     IN_SET(s->deserialized_state,
+                            SERVICE_START, SERVICE_START_POST,
+                            SERVICE_RUNNING, SERVICE_RELOAD,
+                            SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                            SERVICE_STOP_POST,
+                            SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL))) {
+                        r = unit_watch_pid(UNIT(s), s->main_pid);
+                        if (r < 0)
+                                return r;
+                }
 
-                if (s->deserialized_state == SERVICE_START_PRE ||
-                    s->deserialized_state == SERVICE_START ||
-                    s->deserialized_state == SERVICE_START_POST ||
-                    s->deserialized_state == SERVICE_RELOAD ||
-                    s->deserialized_state == SERVICE_STOP ||
-                    s->deserialized_state == SERVICE_STOP_SIGTERM ||
-                    s->deserialized_state == SERVICE_STOP_SIGKILL ||
-                    s->deserialized_state == SERVICE_STOP_POST ||
-                    s->deserialized_state == SERVICE_FINAL_SIGTERM ||
-                    s->deserialized_state == SERVICE_FINAL_SIGKILL)
-                        if (s->control_pid > 0) {
-                                r = unit_watch_pid(UNIT(s), s->control_pid);
-                                if (r < 0)
-                                        return r;
-                        }
+                if (pid_valid(s->control_pid) &&
+                    IN_SET(s->deserialized_state,
+                           SERVICE_START_PRE, SERVICE_START, SERVICE_START_POST,
+                           SERVICE_RELOAD,
+                           SERVICE_STOP, SERVICE_STOP_SIGTERM, SERVICE_STOP_SIGKILL,
+                           SERVICE_STOP_POST,
+                           SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL)) {
+                        r = unit_watch_pid(UNIT(s), s->control_pid);
+                        if (r < 0)
+                                return r;
+                }
 
                 if (IN_SET(s->deserialized_state, SERVICE_START_POST, SERVICE_RUNNING, SERVICE_RELOAD))
                         service_start_watchdog(s);
@@ -3022,6 +3012,14 @@ static void service_sigchld_event(Unit *u, pid_t pid, int code, int status) {
                                 /* If there is still a control process, wait for that first */
                                 break;
 
+                        case SERVICE_STOP_POST:
+                        case SERVICE_FINAL_SIGTERM:
+                        case SERVICE_FINAL_SIGKILL:
+
+                                if (!control_pid_good(s))
+                                        service_enter_dead(s, f, true);
+                                break;
+
                         default:
                                 assert_not_reached("Uh, main process died at wrong time.");
                         }
@@ -3163,7 +3161,8 @@ static void service_sigchld_event(Unit *u, pid_t pid, int code, int status) {
                         case SERVICE_STOP_POST:
                         case SERVICE_FINAL_SIGTERM:
                         case SERVICE_FINAL_SIGKILL:
-                                service_enter_dead(s, f, true);
+                                if (main_pid_good(s) <= 0)
+                                        service_enter_dead(s, f, true);
                                 break;
 
                         default:
@@ -3327,6 +3326,7 @@ static void service_notify_cgroup_empty_event(Unit *u) {
 
                 break;
 
+        case SERVICE_STOP_POST:
         case SERVICE_FINAL_SIGTERM:
         case SERVICE_FINAL_SIGKILL:
                 if (main_pid_good(s) <= 0 && !control_pid_good(s))
diff --git a/src/shared/util.c b/src/shared/util.c
index 2cf9fbe53e..f59897105a 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -6088,3 +6088,13 @@ int namespace_enter(int pidns_fd, int mntns_fd, int root_fd) {
 
         return 0;
 }
+
+bool pid_valid(pid_t pid) {
+        if (pid <= 0)
+                return false;
+
+        if (kill(pid, 0) >= 0)
+                return true;
+
+        return errno != ESRCH;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index ddb35181ab..3e0a6d5c1c 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -804,3 +804,5 @@ int container_get_leader(const char *machine, pid_t *pid);
 
 int namespace_open(pid_t pid, int *pidns_fd, int *mntns_fd, int *root_fd);
 int namespace_enter(int pidns_fd, int mntns_fd, int root_fd);
+
+bool pid_valid(pid_t pid);