[PATCH 06/24] perf daemon: Add config file support

[Jiri Olsa <jolsa@kernel.org>]

Adding support to configure daemon with config file.

Each client or server invocation of perf daemon needs to know the
base directory, where all sessions data is stored.

The base is defined with:

  daemon.base
    Base path for daemon data. All sessions data are stored under
    this path.

The daemon allows to create record sessions. Each session is a
record command spawned and monitored by perf daemon.

The session is defined with:

  session-<NAME>.run
    Defines new record session for daemon. The value is record's
    command line without the 'record' keyword.

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

Example above defines '/opt/perfdata' as a base directory
and 2 record sessions.

  # perf daemon start
  [2021-01-28 19:47:33.454413] daemon started (pid 16015)
  [2021-01-28 19:47:33.455910] reconfig: ruining session [cycles:16016]: -m 10M -e cycles --overwrite --switch-output -a
  [2021-01-28 19:47:33.456599] reconfig: ruining session [sched:16017]: -m 20M -e sched:* --overwrite --switch-output -a

  # ps -ef | grep perf
  ... perf daemon start
  ... /home/jolsa/.../perf record -m 20M -e cycles --overwrite --switch-output -a
  ... /home/jolsa/.../perf record -m 20M -e sched:* --overwrite --switch-output -a

The base directory is populated with:

  # find /opt/perfdata/
  /opt/perfdata/
  /opt/perfdata/control                    <- control socket
  /opt/perfdata/session-cycles             <- data for session 'cycles':
  /opt/perfdata/session-cycles/output      <-   perf record output
  /opt/perfdata/session-cycles/perf.data   <-   perf data
  /opt/perfdata/session-sched              <- ditto for session 'sched'
  /opt/perfdata/session-sched/output
  /opt/perfdata/session-sched/perf.data

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/builtin-daemon.c | 353 +++++++++++++++++++++++++++++++++++-
 1 file changed, 351 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index eada3ceb9b0c..be2ade9967b3 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <subcmd/parse-options.h>
 #include <api/fd/array.h>
+#include <linux/zalloc.h>
+#include <linux/string.h>
 #include <linux/limits.h>
 #include <string.h>
 #include <signal.h>
@@ -13,22 +15,74 @@
 #include <sys/un.h>
 #include <sys/stat.h>
 #include <poll.h>
+#include <sys/stat.h>
 #include "builtin.h"
 #include "perf.h"
 #include "debug.h"
 #include "config.h"
 #include "util.h"
 
+#define SESSION_OUTPUT  "output"
+
+/*
+ * Session states:
+ *
+ *   OK       - session is up and running
+ *   RECONFIG - session is pending for reconfiguration,
+ *              new values are already loaded in session object
+ *   KILL     - session is pending to be killed
+ *
+ * Session object life and its state is maintained by
+ * following functions:
+ *
+ *  setup_server_config
+ *    - reads config file and setup session objects
+ *      with following states:
+ *
+ *      OK       - no change needed
+ *      RECONFIG - session needs to be changed
+ *                 (run variable changed)
+ *      KILL     - session needs to be killed
+ *                 (session is no longer in config file)
+ *
+ *  daemon__reconfig
+ *    - scans session objects and does following actions
+ *      for states:
+ *
+ *      OK       - skip
+ *      RECONFIG - session is killed and re-run with new config
+ *      KILL     - session is killed
+ *
+ *    - all sessions have OK state on the function exit
+ */
+enum session_state {
+	SESSION_STATE__OK,
+	SESSION_STATE__RECONFIG,
+	SESSION_STATE__KILL,
+};
+
+struct session {
+	char			*base;
+	char			*name;
+	char			*run;
+	int			 pid;
+	struct list_head	 list;
+	enum session_state	 state;
+};
+
 struct daemon {
 	const char		*config;
 	char			*config_real;
 	const char		*base_user;
 	char			*base;
+	struct list_head	 sessions;
 	FILE			*out;
 	char			 perf[PATH_MAX];
 };
 
-static struct daemon __daemon = { };
+static struct daemon __daemon = {
+	.sessions = LIST_HEAD_INIT(__daemon.sessions),
+};
 
 static const char * const daemon_usage[] = {
 	"perf daemon start [<options>]",
@@ -43,6 +97,128 @@ static void sig_handler(int sig __maybe_unused)
 	done = true;
 }
 
+static struct session*
+daemon__add_session(struct daemon *config, char *name)
+{
+	struct session *session;
+
+	session = zalloc(sizeof(*session));
+	if (!session)
+		return NULL;
+
+	session->name = strdup(name);
+	if (!session->name) {
+		free(session);
+		return NULL;
+	}
+
+	session->pid = -1;
+	list_add_tail(&session->list, &config->sessions);
+	return session;
+}
+
+static struct session*
+daemon__find_session(struct daemon *daemon, char *name)
+{
+	struct session *session;
+
+	list_for_each_entry(session, &daemon->sessions, list) {
+		if (!strcmp(session->name, name))
+			return session;
+	}
+
+	return NULL;
+}
+
+static int get_session_name(const char *var, char *session, int len)
+{
+	const char *p = var + sizeof("session-") - 1;
+
+	while (*p != '.' && *p != 0x0 && len--)
+		*session++ = *p++;
+
+	*session = 0;
+	return *p == '.' ? 0 : -EINVAL;
+}
+
+static int session_config(struct daemon *daemon, const char *var, const char *value)
+{
+	struct session *session;
+	char name[100];
+
+	if (get_session_name(var, name, sizeof(name)))
+		return -EINVAL;
+
+	var = strchr(var, '.');
+	if (!var)
+		return -EINVAL;
+
+	var++;
+
+	session = daemon__find_session(daemon, name);
+
+	if (!session) {
+		/* New session is defined. */
+		session = daemon__add_session(daemon, name);
+		if (!session)
+			return -ENOMEM;
+
+		pr_debug("reconfig: found new session %s\n", name);
+
+		/* Trigger reconfig to start it. */
+		session->state = SESSION_STATE__RECONFIG;
+	} else if (session->state == SESSION_STATE__KILL) {
+		/* Current session is defined, no action needed. */
+		pr_debug("reconfig: found current session %s\n", name);
+		session->state = SESSION_STATE__OK;
+	}
+
+	if (!strcmp(var, "run")) {
+		bool same = false;
+
+		if (session->run)
+			same = !strcmp(session->run, value);
+
+		if (!same) {
+			if (session->run) {
+				free(session->run);
+				pr_debug("reconfig: session %s is changed\n", name);
+			}
+
+			session->run = strdup(value);
+			if (!session->run)
+				return -ENOMEM;
+
+			/*
+			 * Either new or changed run value is defined,
+			 * trigger reconfig for the session.
+			 */
+			session->state = SESSION_STATE__RECONFIG;
+		}
+	}
+
+	return 0;
+}
+
+static int server_config(const char *var, const char *value, void *cb)
+{
+	struct daemon *daemon = cb;
+
+	if (strstarts(var, "session-"))
+		return session_config(daemon, var, value);
+	else if (!strcmp(var, "daemon.base") && !daemon->base_user) {
+		if (daemon->base && strcmp(daemon->base, value)) {
+			pr_err("failed: can't redefine base, bailing out\n");
+			return -EINVAL;
+		}
+		daemon->base = strdup(value);
+		if (!daemon->base)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
 static int client_config(const char *var, const char *value, void *cb)
 {
 	struct daemon *daemon = cb;
@@ -87,6 +263,91 @@ static int setup_client_config(struct daemon *daemon)
 	return err ?: check_base(daemon);
 }
 
+static int setup_server_config(struct daemon *daemon)
+{
+	struct perf_config_set *set;
+	struct session *session;
+	int err = -ENOMEM;
+
+	pr_debug("reconfig: started\n");
+
+	/*
+	 * Mark all sessions for kill, the server config
+	 * will set following states, see explanation at
+	 * enum session_state declaration.
+	 */
+	list_for_each_entry(session, &daemon->sessions, list)
+		session->state = SESSION_STATE__KILL;
+
+	set = perf_config_set__load_file(daemon->config_real);
+	if (set) {
+		err = perf_config_set(set, server_config, daemon);
+		perf_config_set__delete(set);
+	}
+
+	return err ?: check_base(daemon);
+}
+
+static int session__run(struct session *session, struct daemon *daemon)
+{
+	char buf[PATH_MAX];
+	char **argv;
+	int argc, fd;
+
+	if (asprintf(&session->base, "%s/session-%s",
+		     daemon->base, session->name) < 0) {
+		perror("failed: asprintf");
+		return -1;
+	}
+
+	if (mkdir(session->base, 0755) && errno != EEXIST) {
+		perror("failed: mkdir");
+		return -1;
+	}
+
+	session->pid = fork();
+	if (session->pid < 0)
+		return -1;
+	if (session->pid > 0) {
+		pr_info("reconfig: ruining session [%s:%d]: %s\n",
+			session->name, session->pid, session->run);
+		return 0;
+	}
+
+	if (chdir(session->base)) {
+		perror("failed: chdir");
+		return -1;
+	}
+
+	fd = open("/dev/null", O_RDONLY);
+	if (fd < 0) {
+		perror("failed: open /dev/null");
+		return -1;
+	}
+
+	dup2(fd, 0);
+	close(fd);
+
+	fd = open(SESSION_OUTPUT, O_RDWR|O_CREAT|O_TRUNC, 0644);
+	if (fd < 0) {
+		perror("failed: open session output");
+		return -1;
+	}
+
+	dup2(fd, 1);
+	dup2(fd, 2);
+	close(fd);
+
+	scnprintf(buf, sizeof(buf), "%s record %s", daemon->perf, session->run);
+
+	argv = argv_split(buf, &argc);
+	if (!argv)
+		exit(-1);
+
+	exit(execve(daemon->perf, argv, NULL));
+	return -1;
+}
+
 static int setup_server_socket(struct daemon *daemon)
 {
 	struct sockaddr_un addr;
@@ -185,17 +446,95 @@ static int setup_client_socket(struct daemon *daemon)
 	return fd;
 }
 
+static int session__signal(struct session *session, int sig)
+{
+	if (session->pid < 0)
+		return -1;
+	return kill(session->pid, sig);
+}
+
+static void session__kill(struct session *session)
+{
+	session__signal(session, SIGTERM);
+}
+
+static void daemon__signal(struct daemon *daemon, int sig)
+{
+	struct session *session;
+
+	list_for_each_entry(session, &daemon->sessions, list)
+		session__signal(session, sig);
+}
+
+static void session__free(struct session *session)
+{
+	free(session->base);
+	free(session->name);
+	free(session->run);
+	free(session);
+}
+
+static void session__remove(struct session *session)
+{
+	list_del(&session->list);
+	session__free(session);
+}
+
+static void daemon__kill(struct daemon *daemon)
+{
+	daemon__signal(daemon, SIGTERM);
+}
+
 static void daemon__free(struct daemon *daemon)
 {
+	struct session *session, *h;
+
+	list_for_each_entry_safe(session, h, &daemon->sessions, list)
+		session__remove(session);
+
 	free(daemon->config_real);
 	free(daemon->base);
 }
 
 static void daemon__exit(struct daemon *daemon)
 {
+	daemon__kill(daemon);
 	daemon__free(daemon);
 }
 
+static int daemon__reconfig(struct daemon *daemon)
+{
+	struct session *session, *n;
+
+	list_for_each_entry_safe(session, n, &daemon->sessions, list) {
+		/* No change. */
+		if (session->state == SESSION_STATE__OK)
+			continue;
+
+		/* Remove session. */
+		if (session->state == SESSION_STATE__KILL) {
+			if (session->pid > 0) {
+				session__kill(session);
+				pr_info("reconfig: session '%s' killed\n", session->name);
+			}
+			session__remove(session);
+			continue;
+		}
+
+		/* Reconfig session. */
+		if (session->pid > 0) {
+			session__kill(session);
+			pr_info("reconfig: session '%s' killed\n", session->name);
+		}
+		if (session__run(session, daemon))
+			return -1;
+
+		session->state = SESSION_STATE__OK;
+	}
+
+	return 0;
+}
+
 static int setup_config(struct daemon *daemon)
 {
 	if (daemon->base_user) {
@@ -244,6 +583,9 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 		return -1;
 	}
 
+	if (setup_server_config(daemon))
+		return -1;
+
 	debug_set_file(daemon->out);
 	debug_set_display_time(true);
 
@@ -263,9 +605,16 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 	signal(SIGTERM, sig_handler);
 
 	while (!done && !err) {
-		if (fdarray__poll(&fda, -1)) {
+		err = daemon__reconfig(daemon);
+
+		if (!err && fdarray__poll(&fda, -1)) {
+			bool reconfig = false;
+
 			if (fda.entries[sock_pos].revents & POLLIN)
 				err = handle_server_socket(daemon, sock_fd);
+
+			if (reconfig)
+				err = setup_server_config(daemon);
 		}
 	}
 
-- 
2.29.2