perf daemon: Add 'stop' command

Add 'perf daemon stop' command to stop daemon process and all running
sessions.

Example:

  # cat ~/.perfconfig
  [daemon]
  base=/opt/perfdata

  [session-cycles]
  run = -m 10M -e cycles --overwrite --switch-output -a

  [session-sched]
  run = -m 20M -e sched:* --overwrite --switch-output -a

Start the daemon:

  # perf daemon start

Stop the daemon

  # perf daemon stop

Daemon is not running, nothing to connect to:

  # perf daemon
  connect error: Connection refused

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20210208200908.1019149-13-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-daemon.txt

@@ -13,6 +13,7 @@ SYNOPSIS
 'perf daemon'
 'perf daemon' [<options>]
 'perf daemon start'  [<options>]
+'perf daemon stop'   [<options>]
 'perf daemon signal' [<options>]
 
 
@@ -62,6 +63,11 @@ The start command creates the daemon process.
 	Do not put the process in background.
 
 
+STOP COMMAND
+------------
+The stop command stops all the session and the daemon process.
+
+
 SIGNAL COMMAND
 --------------
 The signal command sends signal to configured sessions.

tools/perf/builtin-daemon.c

@@ -532,6 +532,7 @@ static int setup_server_socket(struct daemon *daemon)
 enum {
 	CMD_LIST   = 0,
 	CMD_SIGNAL = 1,
+	CMD_STOP   = 2,
 	CMD_MAX,
 };
 
@@ -665,6 +666,11 @@ static int handle_server_socket(struct daemon *daemon, int sock_fd)
 	case CMD_SIGNAL:
 		ret = cmd_session_kill(daemon, &cmd, out);
 		break;
+	case CMD_STOP:
+		done = 1;
+		ret = 0;
+		pr_debug("perf daemon is exciting\n");
+		break;
 	default:
 		break;
 	}
@@ -1151,6 +1157,27 @@ static int __cmd_signal(struct daemon *daemon, struct option parent_options[],
 	return send_cmd(daemon, &cmd);
 }
 
+static int __cmd_stop(struct daemon *daemon, struct option parent_options[],
+			int argc, const char **argv)
+{
+	struct option start_options[] = {
+		OPT_PARENT(parent_options),
+		OPT_END()
+	};
+	union cmd cmd = { .cmd = CMD_STOP, };
+
+	argc = parse_options(argc, argv, start_options, daemon_usage, 0);
+	if (argc)
+		usage_with_options(daemon_usage, start_options);
+
+	if (setup_config(daemon)) {
+		pr_err("failed: config not found\n");
+		return -1;
+	}
+
+	return send_cmd(daemon, &cmd);
+}
+
 int cmd_daemon(int argc, const char **argv)
 {
 	struct option daemon_options[] = {
@@ -1175,6 +1202,8 @@ int cmd_daemon(int argc, const char **argv)
 			return __cmd_start(&__daemon, daemon_options, argc, argv);
 		if (!strcmp(argv[0], "signal"))
 			return __cmd_signal(&__daemon, daemon_options, argc, argv);
+		else if (!strcmp(argv[0], "stop"))
+			return __cmd_stop(&__daemon, daemon_options, argc, argv);
 
 		pr_err("failed: unknown command '%s'\n", argv[0]);
 		return -1;