watchdog: add setting to configure pretimeout governor

src/core/dbus-manager.c

@@ -283,6 +283,24 @@ static int property_get_pretimeout_watchdog(
         return sd_bus_message_append(reply, "t", manager_get_watchdog(m, WATCHDOG_PRETIMEOUT));
 }
 
+static int property_get_pretimeout_watchdog_governor(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *property,
+                sd_bus_message *reply,
+                void *userdata,
+                sd_bus_error *error) {
+
+        Manager *m = userdata;
+
+        assert(m);
+        assert(bus);
+        assert(reply);
+
+        return sd_bus_message_append(reply, "s", m->watchdog_pretimeout_governor);
+}
+
 static int property_get_reboot_watchdog(
                 sd_bus *bus,
                 const char *path,
@@ -360,6 +378,30 @@ static int property_set_pretimeout_watchdog(
         return property_set_watchdog(userdata, WATCHDOG_PRETIMEOUT, value);
 }
 
+static int property_set_pretimeout_watchdog_governor(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *property,
+                sd_bus_message *value,
+                void *userdata,
+                sd_bus_error *error) {
+
+        Manager *m = userdata;
+        char *governor;
+        int r;
+
+        assert(m);
+
+        r = sd_bus_message_read(value, "s", &governor);
+        if (r < 0)
+                return r;
+        if (!string_is_safe(governor))
+                return -EINVAL;
+
+        return manager_override_watchdog_pretimeout_governor(m, governor);
+}
+
 static int property_set_reboot_watchdog(
                 sd_bus *bus,
                 const char *path,
@@ -2727,6 +2769,7 @@ const sd_bus_vtable bus_manager_vtable[] = {
         SD_BUS_PROPERTY("DefaultStandardError", "s", bus_property_get_exec_output, offsetof(Manager, default_std_error), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_WRITABLE_PROPERTY("RuntimeWatchdogUSec", "t", property_get_runtime_watchdog, property_set_runtime_watchdog, 0, 0),
         SD_BUS_WRITABLE_PROPERTY("RuntimeWatchdogPreUSec", "t", property_get_pretimeout_watchdog, property_set_pretimeout_watchdog, 0, 0),
+        SD_BUS_WRITABLE_PROPERTY("RuntimeWatchdogPreGovernor", "s", property_get_pretimeout_watchdog_governor, property_set_pretimeout_watchdog_governor, 0, 0),
         SD_BUS_WRITABLE_PROPERTY("RebootWatchdogUSec", "t", property_get_reboot_watchdog, property_set_reboot_watchdog, 0, 0),
         /* The following item is an obsolete alias */
         SD_BUS_WRITABLE_PROPERTY("ShutdownWatchdogUSec", "t", property_get_reboot_watchdog, property_set_reboot_watchdog, 0, SD_BUS_VTABLE_HIDDEN),

src/core/main.c

@@ -140,6 +140,7 @@ static usec_t arg_reboot_watchdog;
 static usec_t arg_kexec_watchdog;
 static usec_t arg_pretimeout_watchdog;
 static char *arg_early_core_pattern;
+static char *arg_watchdog_pretimeout_governor;
 static char *arg_watchdog_device;
 static char **arg_default_environment;
 static char **arg_manager_environment;
@@ -575,6 +576,20 @@ static int parse_proc_cmdline_item(const char *key, const char *value, void *dat
                         }
                 }
 
+        } else if (proc_cmdline_key_streq(key, "systemd.watchdog_pretimeout_governor")) {
+
+                if (proc_cmdline_value_missing(key, value) || isempty(value)) {
+                        arg_watchdog_pretimeout_governor = mfree(arg_watchdog_pretimeout_governor);
+                        return 0;
+                }
+
+                if (!string_is_safe(value)) {
+                        log_warning("Watchdog pretimeout governor '%s' is not valid, ignoring.", value);
+                        return 0;
+                }
+
+                return free_and_strdup_warn(&arg_watchdog_pretimeout_governor, value);
+
         } else if (proc_cmdline_key_streq(key, "systemd.clock_usec")) {
 
                 if (proc_cmdline_value_missing(key, value))
@@ -732,6 +747,7 @@ static int parse_config_file(void) {
                 { "Manager", "ShutdownWatchdogSec",          config_parse_watchdog_sec,          0, &arg_reboot_watchdog                   }, /* obsolete alias */
                 { "Manager", "KExecWatchdogSec",             config_parse_watchdog_sec,          0, &arg_kexec_watchdog                    },
                 { "Manager", "WatchdogDevice",               config_parse_path,                  0, &arg_watchdog_device                   },
+                { "Manager", "RuntimeWatchdogPreGovernor",   config_parse_safe_string,           0, &arg_watchdog_pretimeout_governor      },
                 { "Manager", "CapabilityBoundingSet",        config_parse_capability_set,        0, &arg_capability_bounding_set           },
                 { "Manager", "NoNewPrivileges",              config_parse_bool,                  0, &arg_no_new_privs                      },
 #if HAVE_SECCOMP
@@ -856,6 +872,7 @@ static void set_manager_defaults(Manager *m) {
 }
 
 static void set_manager_settings(Manager *m) {
+        int r;
 
         assert(m);
 
@@ -871,6 +888,9 @@ static void set_manager_settings(Manager *m) {
         manager_set_watchdog(m, WATCHDOG_REBOOT, arg_reboot_watchdog);
         manager_set_watchdog(m, WATCHDOG_KEXEC, arg_kexec_watchdog);
         manager_set_watchdog(m, WATCHDOG_PRETIMEOUT, arg_pretimeout_watchdog);
+        r = manager_set_watchdog_pretimeout_governor(m, arg_watchdog_pretimeout_governor);
+        if (r < 0)
+                log_warning_errno(r, "Failed to set watchdog pretimeout governor to '%s', ignoring: %m", arg_watchdog_pretimeout_governor);
 
         manager_set_show_status(m, arg_show_status, "commandline");
         m->status_unit_format = arg_status_unit_format;
@@ -1618,6 +1638,7 @@ static int become_shutdown(
          * shutdown binary to repeatedly ping it.
          * Disable the pretimeout watchdog, as we do not support it from the shutdown binary. */
         (void) watchdog_setup_pretimeout(0);
+        (void) watchdog_setup_pretimeout_governor(NULL);
         r = watchdog_setup(watchdog_timer);
         watchdog_close(r < 0);
 
@@ -2473,6 +2494,7 @@ static void reset_arguments(void) {
         arg_pretimeout_watchdog = 0;
         arg_early_core_pattern = NULL;
         arg_watchdog_device = NULL;
+        arg_watchdog_pretimeout_governor = mfree(arg_watchdog_pretimeout_governor);
 
         arg_default_environment = strv_free(arg_default_environment);
         arg_manager_environment = strv_free(arg_manager_environment);

src/core/manager-serialize.c

@@ -119,6 +119,7 @@ int manager_serialize(
         (void) serialize_usec(f, "reboot-watchdog-overridden", m->watchdog_overridden[WATCHDOG_REBOOT]);
         (void) serialize_usec(f, "kexec-watchdog-overridden", m->watchdog_overridden[WATCHDOG_KEXEC]);
         (void) serialize_usec(f, "pretimeout-watchdog-overridden", m->watchdog_overridden[WATCHDOG_PRETIMEOUT]);
+        (void) serialize_item(f, "pretimeout-watchdog-governor-overridden", m->watchdog_pretimeout_governor_overridden);
 
         for (ManagerTimestamp q = 0; q < _MANAGER_TIMESTAMP_MAX; q++) {
                 _cleanup_free_ char *joined = NULL;
@@ -464,6 +465,11 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
                         else
                                 manager_override_watchdog(m, WATCHDOG_PRETIMEOUT, t);
 
+                } else if ((val = startswith(l, "pretimeout-watchdog-governor-overridden="))) {
+                        r = free_and_strdup(&m->watchdog_pretimeout_governor_overridden, val);
+                        if (r < 0)
+                                return r;
+
                 } else if (startswith(l, "env=")) {
                         r = deserialize_environment(l + 4, &m->client_environment);
                         if (r < 0)

src/core/manager.c

@@ -1542,6 +1542,9 @@ Manager* manager_free(Manager *m) {
                 m->prefix[dt] = mfree(m->prefix[dt]);
         free(m->received_credentials);
 
+        free(m->watchdog_pretimeout_governor);
+        free(m->watchdog_pretimeout_governor_overridden);
+
 #if BPF_FRAMEWORK
         lsm_bpf_destroy(m->restrict_fs);
 #endif
@@ -3263,6 +3266,52 @@ void manager_override_watchdog(Manager *m, WatchdogType t, usec_t timeout) {
         m->watchdog_overridden[t] = timeout;
 }
 
+int manager_set_watchdog_pretimeout_governor(Manager *m, const char *governor) {
+        _cleanup_free_ char *p = NULL;
+        int r;
+
+        assert(m);
+
+        if (MANAGER_IS_USER(m))
+                return 0;
+
+        if (streq_ptr(m->watchdog_pretimeout_governor, governor))
+                return 0;
+
+        p = strdup(governor);
+        if (!p)
+                return -ENOMEM;
+
+        r = watchdog_setup_pretimeout_governor(governor);
+        if (r < 0)
+                return r;
+
+        return free_and_replace(m->watchdog_pretimeout_governor, p);
+}
+
+int manager_override_watchdog_pretimeout_governor(Manager *m, const char *governor) {
+        _cleanup_free_ char *p = NULL;
+        int r;
+
+        assert(m);
+
+        if (MANAGER_IS_USER(m))
+                return 0;
+
+        if (streq_ptr(m->watchdog_pretimeout_governor_overridden, governor))
+                return 0;
+
+        p = strdup(governor);
+        if (!p)
+                return -ENOMEM;
+
+        r = watchdog_setup_pretimeout_governor(governor);
+        if (r < 0)
+                return r;
+
+        return free_and_replace(m->watchdog_pretimeout_governor_overridden, p);
+}
+
 int manager_reload(Manager *m) {
         _unused_ _cleanup_(manager_reloading_stopp) Manager *reloading = NULL;
         _cleanup_fdset_free_ FDSet *fds = NULL;

src/core/manager.h

@@ -248,6 +248,8 @@ struct Manager {
 
         usec_t watchdog[_WATCHDOG_TYPE_MAX];
         usec_t watchdog_overridden[_WATCHDOG_TYPE_MAX];
+        char *watchdog_pretimeout_governor;
+        char *watchdog_pretimeout_governor_overridden;
 
         dual_timestamp timestamps[_MANAGER_TIMESTAMP_MAX];
 
@@ -575,6 +577,8 @@ ManagerTimestamp manager_timestamp_initrd_mangle(ManagerTimestamp s);
 usec_t manager_get_watchdog(Manager *m, WatchdogType t);
 void manager_set_watchdog(Manager *m, WatchdogType t, usec_t timeout);
 void manager_override_watchdog(Manager *m, WatchdogType t, usec_t timeout);
+int manager_set_watchdog_pretimeout_governor(Manager *m, const char *governor);
+int manager_override_watchdog_pretimeout_governor(Manager *m, const char *governor);
 
 const char* oom_policy_to_string(OOMPolicy i) _const_;
 OOMPolicy oom_policy_from_string(const char *s) _pure_;

src/core/system.conf.in

@@ -31,6 +31,7 @@
 #NUMAMask=
 #RuntimeWatchdogSec=off
 #RuntimeWatchdogPreSec=off
+#RuntimeWatchdogPreGovernor=
 #RebootWatchdogSec=10min
 #KExecWatchdogSec=off
 #WatchdogDevice=

src/shared/watchdog.c

@@ -22,6 +22,7 @@ static usec_t watchdog_timeout; /* 0 → close device and USEC_INFINITY → don'
 static usec_t watchdog_pretimeout; /* 0 → disable pretimeout and USEC_INFINITY → don't change pretimeout */
 static usec_t watchdog_last_ping = USEC_INFINITY;
 static bool watchdog_supports_pretimeout = false; /* Depends on kernel state that might change at runtime */
+static char *watchdog_pretimeout_governor = NULL;
 
 /* Starting from kernel version 4.5, the maximum allowable watchdog timeout is
  * UINT_MAX/1000U seconds (since internal calculations are done in milliseconds
@@ -76,6 +77,28 @@ static int get_pretimeout_governor(char **ret_gov) {
         return 0;
 }
 
+static int set_pretimeout_governor(const char *governor) {
+        _cleanup_free_ char *sys_fn = NULL;
+        int r;
+
+        if (isempty(governor))
+                return 0; /* Nothing to do */
+
+        r = get_watchdog_sysfs_path("pretimeout_governor", &sys_fn);
+        if (r < 0)
+                return r;
+
+        log_info("Watchdog: setting pretimeout_governor to '%s' via '%s'", governor, sys_fn);
+
+        r = write_string_file(sys_fn,
+                              governor,
+                              WRITE_STRING_FILE_DISABLE_BUFFER | WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set pretimeout_governor to '%s': %m", governor);
+
+        return r;
+}
+
 static int watchdog_set_enable(bool enable) {
         int flags = enable ? WDIOS_ENABLECARD : WDIOS_DISABLECARD;
 
@@ -194,6 +217,9 @@ static int update_pretimeout(void) {
          * might have been unloaded. */
         watchdog_supports_pretimeout = false;
 
+        /* Update the pretimeout governor as well */
+        (void) set_pretimeout_governor(watchdog_pretimeout_governor);
+
         r = get_pretimeout_governor(&governor);
         if (r < 0)
                 return log_warning_errno(r, "Watchdog: failed to read pretimeout governor: %m");
@@ -362,6 +388,13 @@ int watchdog_setup_pretimeout(usec_t timeout) {
         return update_pretimeout();
 }
 
+int watchdog_setup_pretimeout_governor(const char *governor) {
+        if (free_and_strdup(&watchdog_pretimeout_governor, governor) < 0)
+                return -ENOMEM;
+
+        return set_pretimeout_governor(watchdog_pretimeout_governor);
+}
+
 static usec_t calc_timeout(void) {
         /* Calculate the effective timeout which accounts for the watchdog
          * pretimeout if configured and supported. */

src/shared/watchdog.h

@@ -9,6 +9,7 @@
 int watchdog_set_device(const char *path);
 int watchdog_setup(usec_t timeout);
 int watchdog_setup_pretimeout(usec_t usec);
+int watchdog_setup_pretimeout_governor(const char *governor);
 int watchdog_ping(void);
 void watchdog_close(bool disarm);
 usec_t watchdog_runtime_wait(void);