core: Record ExecMainStartTimestamp before forking

Otherwise there's a chance the handover timestamp is less than the
start timestamp depending on the whims of the scheduler.

For non-forking services, we also propagate the start timestamp into
Service->main_exec_status to make sure it starts earlier than the
handoff timestamp.

diff --git a/src/core/execute.c b/src/core/execute.c
index 80d5b30720bc7a6a9b62bded7f4197f57a4cf436..9b953f980fd08387d22623d2ed59195c81d93e5d 100644 (file)
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -366,6 +366,7 @@ int exec_spawn(Unit *unit,
         _cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
         _cleanup_fdset_free_ FDSet *fdset = NULL;
         _cleanup_fclose_ FILE *f = NULL;
+        dual_timestamp start_timestamp;
         int r;
 
         assert(unit);
@@ -446,6 +447,10 @@ int exec_spawn(Unit *unit,
 
         xsprintf(serialization_fd_number, "%i", fileno(f));
 
+        /* Record the start timestamp before we fork so that it is guaranteed to be earlier than the
+         * handoff timestamp. */
+        dual_timestamp_now(&start_timestamp);
+
         /* The executor binary is pinned, to avoid compatibility problems during upgrades. */
         r = posix_spawn_wrapper(
                         FORMAT_PROC_FD_PATH(unit->manager->executor_fd),
@@ -473,7 +478,7 @@ int exec_spawn(Unit *unit,
         log_unit_debug(unit, "Forked %s as " PID_FMT " (%s CLONE_INTO_CGROUP)",
                        command->path, pidref.pid, r > 0 ? "via" : "without");
 
-        exec_status_start(&command->exec_status, pidref.pid);
+        exec_status_start(&command->exec_status, pidref.pid, &start_timestamp);
 
         *ret = TAKE_PIDREF(pidref);
         return 0;
@@ -1816,14 +1821,17 @@ char** exec_context_get_restrict_filesystems(const ExecContext *c) {
         return l ? TAKE_PTR(l) : strv_new(NULL);
 }
 
-void exec_status_start(ExecStatus *s, pid_t pid) {
+void exec_status_start(ExecStatus *s, pid_t pid, const dual_timestamp *ts) {
         assert(s);
 
         *s = (ExecStatus) {
                 .pid = pid,
         };
 
-        dual_timestamp_now(&s->start_timestamp);
+        if (ts)
+                s->start_timestamp = *ts;
+        else
+                dual_timestamp_now(&s->start_timestamp);
 }
 
 void exec_status_exit(ExecStatus *s, const ExecContext *context, pid_t pid, int code, int status) {

diff --git a/src/core/execute.h b/src/core/execute.h
index 77ca1901e7eec1a12c62c402a4c1b86e2581ac41..b782967c8761744ccab3dcd90b228780662c4fb9 100644 (file)
--- a/src/core/execute.h
+++ b/src/core/execute.h
@@ -542,7 +542,7 @@ char** exec_context_get_syscall_log(const ExecContext *c);
 char** exec_context_get_address_families(const ExecContext *c);
 char** exec_context_get_restrict_filesystems(const ExecContext *c);
 
-void exec_status_start(ExecStatus *s, pid_t pid);
+void exec_status_start(ExecStatus *s, pid_t pid, const dual_timestamp *ts);
 void exec_status_exit(ExecStatus *s, const ExecContext *context, pid_t pid, int code, int status);
 void exec_status_handoff(ExecStatus *s, const struct ucred *ucred, const dual_timestamp *ts);
 void exec_status_dump(const ExecStatus *s, FILE *f, const char *prefix);

diff --git a/src/core/service.c b/src/core/service.c
index c527ad36bc7c34aa5cca22cbe56797e3a528259c..36671ae1c0f72f50c4394f87bc0c2967c8d47990 100644 (file)
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -192,7 +192,7 @@ static void service_unwatch_pid_file(Service *s) {
         s->pid_file_pathspec = mfree(s->pid_file_pathspec);
 }
 
-static int service_set_main_pidref(Service *s, PidRef pidref_consume) {
+static int service_set_main_pidref(Service *s, PidRef pidref_consume, const dual_timestamp *start_timestamp) {
         _cleanup_(pidref_done) PidRef pidref = pidref_consume;
         int r;
 
@@ -214,7 +214,7 @@ static int service_set_main_pidref(Service *s, PidRef pidref_consume) {
 
         if (!pidref_equal(&s->main_pid, &pidref)) {
                 service_unwatch_main_pid(s);
-                exec_status_start(&s->main_exec_status, pidref.pid);
+                exec_status_start(&s->main_exec_status, pidref.pid, start_timestamp);
         }
 
         s->main_pid = TAKE_PIDREF(pidref);
@@ -1166,7 +1166,7 @@ static int service_load_pid_file(Service *s, bool may_warn) {
         } else
                 log_unit_debug(UNIT(s), "Main PID loaded: "PID_FMT, pidref.pid);
 
-        r = service_set_main_pidref(s, TAKE_PIDREF(pidref));
+        r = service_set_main_pidref(s, TAKE_PIDREF(pidref), /* start_timestamp = */ NULL);
         if (r < 0)
                 return r;
 
@@ -1196,7 +1196,7 @@ static void service_search_main_pid(Service *s) {
                 return;
 
         log_unit_debug(UNIT(s), "Main PID guessed: "PID_FMT, pid.pid);
-        if (service_set_main_pidref(s, TAKE_PIDREF(pid)) < 0)
+        if (service_set_main_pidref(s, TAKE_PIDREF(pid), /* start_timestamp = */ NULL) < 0)
                 return;
 
         r = unit_watch_pidref(UNIT(s), &s->main_pid, /* exclusive= */ false);
@@ -2417,7 +2417,7 @@ static void service_enter_start(Service *s) {
                 /* For simple services we immediately start
                  * the START_POST binaries. */
 
-                (void) service_set_main_pidref(s, TAKE_PIDREF(pidref));
+                (void) service_set_main_pidref(s, TAKE_PIDREF(pidref), &c->exec_status.start_timestamp);
                 service_enter_start_post(s);
 
         } else  if (s->type == SERVICE_FORKING) {
@@ -2436,7 +2436,7 @@ static void service_enter_start(Service *s) {
                 /* For D-Bus services we know the main pid right away, but wait for the bus name to appear on the
                  * bus. 'notify' and 'exec' services are similar. */
 
-                (void) service_set_main_pidref(s, TAKE_PIDREF(pidref));
+                (void) service_set_main_pidref(s, TAKE_PIDREF(pidref), &c->exec_status.start_timestamp);
                 service_set_state(s, SERVICE_START);
         } else
                 assert_not_reached();
@@ -2709,7 +2709,7 @@ static void service_run_next_main(Service *s) {
                 return;
         }
 
-        (void) service_set_main_pidref(s, TAKE_PIDREF(pidref));
+        (void) service_set_main_pidref(s, TAKE_PIDREF(pidref), &s->main_command->exec_status.start_timestamp);
 }
 
 static int service_start(Unit *u) {
@@ -3187,7 +3187,7 @@ static int service_deserialize_item(Unit *u, const char *key, const char *value,
                 PidRef pidref;
 
                 if (!pidref_is_set(&s->main_pid) && deserialize_pidref(fds, value, &pidref) >= 0)
-                        (void) service_set_main_pidref(s, pidref);
+                        (void) service_set_main_pidref(s, pidref, /* start_timestamp = */ NULL);
 
         } else if (streq(key, "main-pid-known")) {
                 int b;
@@ -4380,7 +4380,7 @@ static void service_notify_message(
                                         log_unit_warning(u, "New main PID "PID_FMT" does not belong to service, refusing.", new_main_pid.pid);
                         }
                         if (r > 0) {
-                                (void) service_set_main_pidref(s, TAKE_PIDREF(new_main_pid));
+                                (void) service_set_main_pidref(s, TAKE_PIDREF(new_main_pid), /* start_timestamp = */ NULL);
 
                                 r = unit_watch_pidref(UNIT(s), &s->main_pid, /* exclusive= */ false);
                                 if (r < 0)
@@ -4676,7 +4676,7 @@ static int bus_name_pid_lookup_callback(sd_bus_message *reply, void *userdata, s
 
         log_unit_debug(UNIT(s), "D-Bus name %s is now owned by process " PID_FMT, s->bus_name, pidref.pid);
 
-        (void) service_set_main_pidref(s, TAKE_PIDREF(pidref));
+        (void) service_set_main_pidref(s, TAKE_PIDREF(pidref), /* start_timestamp = */ NULL);
         (void) unit_watch_pidref(UNIT(s), &s->main_pid, /* exclusive= */ false);
         return 1;
 }