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From:   Jiri Olsa <jolsa@kernel.org>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     lkml <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Michael Petlan <mpetlan@redhat.com>,
        Ian Rogers <irogers@google.com>,
        Alexei Budankov <abudankov@huawei.com>
Subject: [PATCH 15/24] perf daemon: Add ping command
Date:   Mon,  8 Feb 2021 21:08:59 +0100
Message-Id: <20210208200908.1019149-16-jolsa@kernel.org>
In-Reply-To: <20210208200908.1019149-1-jolsa@kernel.org>
References: <20210208200908.1019149-1-jolsa@kernel.org>
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Adding ping command to verify the perf record session
is up and operational.

It's used in following patches via test code to make
sure perf record is ready to receive signals.

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

Starting the daemon:

  # perf daemon start

Ping all sessions:

  # perf daemon ping
  OK   cycles
  OK   sched

Ping specific session:

  # perf daemon ping --session sched
  OK   sched

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/Documentation/perf-daemon.txt |   9 ++
 tools/perf/builtin-daemon.c              | 149 +++++++++++++++++++++++
 2 files changed, 158 insertions(+)

diff --git a/tools/perf/Documentation/perf-daemon.txt b/tools/perf/Documentation/perf-daemon.txt
index b1acd468b89c..90b20bea6356 100644
--- a/tools/perf/Documentation/perf-daemon.txt
+++ b/tools/perf/Documentation/perf-daemon.txt
@@ -15,6 +15,7 @@ SYNOPSIS
 'perf daemon start'  [<options>]
 'perf daemon stop'   [<options>]
 'perf daemon signal' [<options>]
+'perf daemon ping'   [<options>]
 
 
 DESCRIPTION
@@ -80,6 +81,14 @@ The signal command sends signal to configured sessions.
 	Send signal to specific session.
 
 
+PING COMMAND
+------------
+The ping command sends control ping to configured sessions.
+
+--session::
+	Send ping to specific session.
+
+
 CONFIG FILE
 -----------
 The daemon is configured within standard perf config file by
diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index 7414041ae31d..17ab8f9021ca 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -499,6 +499,78 @@ static int daemon__wait(struct daemon *daemon, int secs)
 	return 0;
 }
 
+static int daemon_session__control(struct daemon_session *session,
+				   const char *msg, bool do_ack)
+{
+	struct pollfd pollfd = { 0, };
+	char control_path[PATH_MAX];
+	char ack_path[PATH_MAX];
+	int control, ack = -1, len;
+	char buf[20];
+	int ret = -1;
+	ssize_t err;
+
+	/* open the control file */
+	scnprintf(control_path, sizeof(control_path), "%s/%s",
+		  session->base, SESSION_CONTROL);
+
+	control = open(control_path, O_WRONLY|O_NONBLOCK);
+	if (!control)
+		return -1;
+
+	if (do_ack) {
+		/* open the ack file */
+		scnprintf(ack_path, sizeof(ack_path), "%s/%s",
+			  session->base, SESSION_ACK);
+
+		ack = open(ack_path, O_RDONLY, O_NONBLOCK);
+		if (!ack) {
+			close(control);
+			return -1;
+		}
+	}
+
+	/* write the command */
+	len = strlen(msg);
+
+	err = writen(control, msg, len);
+	if (err != len) {
+		pr_err("failed: write to control pipe: %d (%s)\n",
+		       errno, control_path);
+		goto out;
+	}
+
+	if (!do_ack)
+		goto out;
+
+	/* wait for an ack */
+	pollfd.fd = ack;
+	pollfd.events = POLLIN;
+
+	if (!poll(&pollfd, 1, 2000)) {
+		pr_err("failed: control ack timeout\n");
+		goto out;
+	}
+
+	if (!pollfd.revents & POLLIN) {
+		pr_err("failed: did not received an ack\n");
+		goto out;
+	}
+
+	err = read(ack, buf, sizeof(buf));
+	if (err > 0)
+		ret = strcmp(buf, "ack\n");
+	else
+		perror("failed: read ack %d\n");
+
+out:
+	if (ack != -1)
+		close(ack);
+
+	close(control);
+	return ret;
+}
+
 static int setup_server_socket(struct daemon *daemon)
 {
 	struct sockaddr_un addr;
@@ -549,6 +621,7 @@ enum {
 	CMD_LIST   = 0,
 	CMD_SIGNAL = 1,
 	CMD_STOP   = 2,
+	CMD_PING   = 3,
 	CMD_MAX,
 };
 
@@ -570,8 +643,25 @@ union cmd {
 		int	sig;
 		char	name[SESSION_MAX];
 	} signal;
+
+	/* CMD_PING */
+	struct {
+		int	cmd;
+		char	name[SESSION_MAX];
+	} ping;
+};
+
+enum {
+	PING_OK	  = 0,
+	PING_FAIL = 1,
+	PING_MAX,
 };
 
+static int daemon_session__ping(struct daemon_session *session)
+{
+	return daemon_session__control(session, "ping", true) ?  PING_FAIL : PING_OK;
+}
+
 static int cmd_session_list(struct daemon *daemon, union cmd *cmd, FILE *out)
 {
 	char csv_sep = cmd->list.csv_sep;
@@ -668,6 +758,34 @@ static int cmd_session_kill(struct daemon *daemon, union cmd *cmd, FILE *out)
 	return 0;
 }
 
+static const char *ping_str[PING_MAX] = {
+	[PING_OK]   = "OK",
+	[PING_FAIL] = "FAIL",
+};
+
+static int cmd_session_ping(struct daemon *daemon, union cmd *cmd, FILE *out)
+{
+	struct daemon_session *session;
+	bool all = false, found = false;
+
+	all = !strcmp(cmd->ping.name, "all");
+
+	list_for_each_entry(session, &daemon->sessions, list) {
+		if (all || !strcmp(cmd->ping.name, session->name)) {
+			int state = daemon_session__ping(session);
+
+			fprintf(out, "%-4s %s\n", ping_str[state], session->name);
+			found = true;
+		}
+	}
+
+	if (!found && !all) {
+		fprintf(out, "%-4s %s (not found)\n",
+			ping_str[PING_FAIL], cmd->ping.name);
+	}
+	return 0;
+}
+
 static int handle_server_socket(struct daemon *daemon, int sock_fd)
 {
 	int ret = -1, fd;
@@ -703,6 +821,9 @@ static int handle_server_socket(struct daemon *daemon, int sock_fd)
 		ret = 0;
 		pr_debug("perf daemon is exciting\n");
 		break;
+	case CMD_PING:
+		ret = cmd_session_ping(daemon, &cmd, out);
+		break;
 	default:
 		break;
 	}
@@ -1124,6 +1245,7 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 
 	signal(SIGINT, sig_handler);
 	signal(SIGTERM, sig_handler);
+	signal(SIGPIPE, SIG_IGN);
 
 	while (!done && !err) {
 		err = daemon__reconfig(daemon);
@@ -1261,6 +1383,31 @@ static int __cmd_stop(struct daemon *daemon, struct option parent_options[],
 	return send_cmd(daemon, &cmd);
 }
 
+static int __cmd_ping(struct daemon *daemon, struct option parent_options[],
+		      int argc, const char **argv)
+{
+	const char *name = "all";
+	struct option ping_options[] = {
+		OPT_STRING(0, "session", &name, "session",
+			"Ping to specific session"),
+		OPT_PARENT(parent_options),
+		OPT_END()
+	};
+	union cmd cmd = { .cmd = CMD_PING, };
+
+	argc = parse_options(argc, argv, ping_options, daemon_usage, 0);
+	if (argc)
+		usage_with_options(daemon_usage, ping_options);
+
+	if (setup_config(daemon)) {
+		pr_err("failed: config not found\n");
+		return -1;
+	}
+
+	scnprintf(cmd.ping.name, sizeof(cmd.ping.name), "%s", name);
+	return send_cmd(daemon, &cmd);
+}
+
 int cmd_daemon(int argc, const char **argv)
 {
 	struct option daemon_options[] = {
@@ -1287,6 +1434,8 @@ int cmd_daemon(int argc, const char **argv)
 			return __cmd_signal(&__daemon, daemon_options, argc, argv);
 		else if (!strcmp(argv[0], "stop"))
 			return __cmd_stop(&__daemon, daemon_options, argc, argv);
+		else if (!strcmp(argv[0], "ping"))
+			return __cmd_ping(&__daemon, daemon_options, argc, argv);
 
 		pr_err("failed: unknown command '%s'\n", argv[0]);
 		return -1;
-- 
2.29.2