add RestartGamemode command

This allows gamemode to leave the context and then enter it again, which
re-applies all system optimizations. It is useful in cases where another
program (like TLP) may override gamemode's optimizations.

This is exposed to users by the -R or --restart flags to gamemoded.

daemon/gamemode-context.c

@@ -934,6 +934,49 @@ int game_mode_context_query_status(GameModeContext *self, pid_t client, pid_t re
 	return ret;
 }
 
+int game_mode_context_restart(GameModeContext *self, pid_t client, pid_t requester)
+{
+	/* First check the requester settings */
+	{
+		char *executable = game_mode_context_find_exe(requester);
+		if (!executable) {
+			return -1;
+		}
+
+		/* Check our blacklist and whitelist */
+		if (!config_get_supervisor_whitelisted(self->config, executable)) {
+			LOG_MSG("Supervisor [%s] was rejected (not in whitelist)\n", executable);
+			free(executable);
+			return -2;
+		} else if (config_get_supervisor_blacklisted(self->config, executable)) {
+			LOG_MSG("Supervisor [%s] was rejected (in blacklist)\n", executable);
+			free(executable);
+			return -2;
+		}
+
+		free(executable);
+	}
+
+	/*
+	 * Check the current refcount on gamemode, this equates to whether gamemode is active or not,
+	 * see game_mode_context_register and game_mode_context_unregister
+	 */
+	if (!atomic_load_explicit(&self->refcount, memory_order_seq_cst)) {
+		return 1;
+	}
+
+	/* Requires locking. */
+	pthread_rwlock_rdlock(&self->rwlock);
+
+	game_mode_context_leave(self);
+	game_mode_context_enter(self);
+
+	/* Unlock here, potentially yielding */
+	pthread_rwlock_unlock(&self->rwlock);
+
+	return 0;
+}
+
 /**
  * Construct a new GameModeClient for the given process ID
  *

daemon/gamemode-dbus.c

@@ -133,6 +133,26 @@ static int method_query_status(sd_bus_message *m, void *userdata,
 	return sd_bus_reply_method_return(m, "i", status);
 }
 
+/**
+ * Handles the RestartGamemode D-BUS Method
+ */
+static int method_restart_gamemode(sd_bus_message *m, void *userdata,
+                                   __attribute__((unused)) sd_bus_error *ret_error)
+{
+	int pid = 0;
+	GameModeContext *context = userdata;
+
+	int ret = sd_bus_message_read(m, "i", &pid);
+	if (ret < 0) {
+		LOG_ERROR("Failed to parse input parameters: %s\n", strerror(-ret));
+		return ret;
+	}
+
+	int status = game_mode_context_restart(context, (pid_t)pid, (pid_t)pid);
+
+	return sd_bus_reply_method_return(m, "i", status);
+}
+
 /**
  * Handles the RegisterGameByPID D-BUS Method
  */
@@ -402,6 +422,7 @@ static const sd_bus_vtable gamemode_vtable[] = {
 	SD_BUS_METHOD("RegisterGame", "i", "i", method_register_game, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("UnregisterGame", "i", "i", method_unregister_game, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("QueryStatus", "i", "i", method_query_status, SD_BUS_VTABLE_UNPRIVILEGED),
+	SD_BUS_METHOD("RestartGamemode", "i", "i", method_restart_gamemode, SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("RegisterGameByPID", "ii", "i", method_register_game_by_pid,
 	              SD_BUS_VTABLE_UNPRIVILEGED),
 	SD_BUS_METHOD("UnregisterGameByPID", "ii", "i", method_unregister_game_by_pid,

daemon/gamemode.h

@@ -155,6 +155,16 @@ int game_mode_context_unregister(GameModeContext *self, pid_t pid, pid_t request
  */
 int game_mode_context_query_status(GameModeContext *self, pid_t pid, pid_t requester);
 
+/**
+ * Restart gamemode if it is running
+ *
+ * @param pid Process ID for the remote client
+ * @returns 0 if gamemode was restarted
+ *          1 if gamemode was already deactivated
+ *          -2 if this request was rejected
+ */
+int game_mode_context_restart(GameModeContext *self, pid_t pid, pid_t requester);
+
 /**
  * Query the config of a gamemode context
  *

daemon/gamemoded.c

@@ -70,6 +70,7 @@ POSSIBILITY OF SUCH DAMAGE.
 	"                           When no PID given, requests gamemode and pauses\n"                 \
 	"  -s[PID], --status=[PID]  Query the status of gamemode for process\n"                        \
 	"                           When no PID given, queries the status globally\n"                  \
+	"  -R, --reset              If gamemode is currently running, stop it, then restart\n"         \
 	"  -d, --daemonize          Daemonize self after launch\n"                                     \
 	"  -l, --log-to-syslog      Log to syslog\n"                                                   \
 	"  -t, --test               Run tests\n"                                                       \
@@ -158,12 +159,17 @@ int main(int argc, char *argv[])
 
 	/* Options struct for getopt_long */
 	static struct option long_options[] = {
-		{ "daemonize", no_argument, 0, 'd' },     { "log-to-syslog", no_argument, 0, 'l' },
-		{ "request", optional_argument, 0, 'r' }, { "test", no_argument, 0, 't' },
-		{ "status", optional_argument, 0, 's' },  { "help", no_argument, 0, 'h' },
-		{ "version", no_argument, 0, 'v' },       { NULL, 0, NULL, 0 },
+		{ "daemonize", no_argument, 0, 'd' },
+		{ "log-to-syslog", no_argument, 0, 'l' },
+		{ "request", optional_argument, 0, 'r' },
+		{ "test", no_argument, 0, 't' },
+		{ "status", optional_argument, 0, 's' },
+		{ "reset", no_argument, 0, 'R' },
+		{ "help", no_argument, 0, 'h' },
+		{ "version", no_argument, 0, 'v' },
+		{ NULL, 0, NULL, 0 },
 	};
-	static const char *short_options = "dls::r::tvh";
+	static const char *short_options = "dls::r::tvhR";
 
 	while ((opt = getopt_long(argc, argv, short_options, long_options, 0)) != -1) {
 		switch (opt) {
@@ -289,6 +295,20 @@ int main(int argc, char *argv[])
 
 			exit(EXIT_SUCCESS);
 
+		case 'R':
+			switch (gamemode_request_restart()) {
+			case 0: /* success */
+				LOG_MSG("gamemode restart succeeded\n");
+				exit(EXIT_SUCCESS);
+			case 1: /* already off */
+				LOG_ERROR("gamemode was already deactivated\n");
+				break;
+			case -1: /* error */
+				LOG_ERROR("gamemode_request_restart failed: %s\n", gamemode_error_string());
+				break;
+			}
+			exit(EXIT_FAILURE);
+
 		case 't': {
 			int status = game_mode_run_client_tests();
 			exit(status);