Commit 3cda0625 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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perf daemon: Add config file change check 



Add support to detect changes to the daemon's config file triggering a
re-read of the configuration when that happens.

Use a inotify file descriptor plugged into the main fdarray object for
polling.

Example:

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

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

Starting the daemon:

  # perf daemon start

Check sessions:

  # perf daemon
  [772262:daemon] base: /opt/perfdata
  [772263:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a

Change '-m 10M' to '-m 20M', and check daemon log:

  # tail -f /opt/perfdata/output
  [2021-01-02 20:31:41.234045] daemon started (pid 772262)
  [2021-01-02 20:31:41.235072] reconfig: ruining session [cycles:772263]: -m 10M -e cycles --overwrite --switch-output -a
  [2021-01-02 20:32:08.310137] reconfig: session 'cycles' killed
  [2021-01-02 20:32:08.310847] reconfig: ruining session [cycles:772338]: -m 20M -e cycles --overwrite --switch-output -a

And the session list:

  # perf daemon
  [772262:daemon] base: /opt/perfdata
  [772338:cycles] perf record -m 20M -e cycles --overwrite --switch-output -a

Note the changed '-m 20M' option is in place.

Signed-off-by: default avatarJiri 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/20210208200908.1019149-8-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c0666261

tools/perf/builtin-daemon.c

+97 −3
Original line number Diff line number Diff line
@@ -12,6 +12,8 @@ 
#include <stdio.h>

#include <unistd.h>

#include <errno.h>

#include <sys/inotify.h>

#include <libgen.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <sys/un.h>
@@ -75,6 +77,7 @@ struct daemon_session { 
struct daemon {

	const char		*config;

	char			*config_real;

	char			*config_base;

	const char		*base_user;

	char			*base;

	struct list_head	 sessions;
@@ -530,6 +533,7 @@ static void daemon__exit(struct daemon *daemon) 
		daemon_session__remove(session);



	free(daemon->config_real);

	free(daemon->config_base);

	free(daemon->base);

}
@@ -566,6 +570,84 @@ static int daemon__reconfig(struct daemon *daemon) 
	return 0;

}



static int setup_config_changes(struct daemon *daemon)

{

	char *basen = strdup(daemon->config_real);

	char *dirn  = strdup(daemon->config_real);

	char *base, *dir;

	int fd, wd = -1;



	if (!dirn || !basen)

		goto out;



	fd = inotify_init1(IN_NONBLOCK|O_CLOEXEC);

	if (fd < 0) {

		perror("failed: inotify_init");

		goto out;

	}



	dir = dirname(dirn);

	base = basename(basen);

	pr_debug("config file: %s, dir: %s\n", base, dir);



	wd = inotify_add_watch(fd, dir, IN_CLOSE_WRITE);

	if (wd >= 0) {

		daemon->config_base = strdup(base);

		if (!daemon->config_base) {

			close(fd);

			wd = -1;

		}

	} else {

		perror("failed: inotify_add_watch");

	}



out:

	free(basen);

	free(dirn);

	return wd < 0 ? -1 : fd;

}



static bool process_inotify_event(struct daemon *daemon, char *buf, ssize_t len)

{

	char *p = buf;



	while (p < (buf + len)) {

		struct inotify_event *event = (struct inotify_event *) p;



		/*

		 * We monitor config directory, check if our

		 * config file was changes.

		 */

		if ((event->mask & IN_CLOSE_WRITE) &&

		    !(event->mask & IN_ISDIR)) {

			if (!strcmp(event->name, daemon->config_base))

				return true;

		}

		p += sizeof(*event) + event->len;

	}

	return false;

}



static int handle_config_changes(struct daemon *daemon, int conf_fd,

				 bool *config_changed)

{

	char buf[4096];

	ssize_t len;



	while (!(*config_changed)) {

		len = read(conf_fd, buf, sizeof(buf));

		if (len == -1) {

			if (errno != EAGAIN) {

				perror("failed: read");

				return -1;

			}

			return 0;

		}

		*config_changed = process_inotify_event(daemon, buf, len);

	}

	return 0;

}



static int setup_config(struct daemon *daemon)

{

	if (daemon->base_user) {
@@ -600,8 +682,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
		OPT_PARENT(parent_options),

		OPT_END()

	};

	int sock_fd = -1;

	int sock_pos;

	int sock_fd = -1, conf_fd = -1;

	int sock_pos, file_pos;

	struct fdarray fda;

	int err = 0;
@@ -622,16 +704,24 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 


	pr_info("daemon started (pid %d)\n", getpid());



	fdarray__init(&fda, 1);

	fdarray__init(&fda, 2);



	sock_fd = setup_server_socket(daemon);

	if (sock_fd < 0)

		goto out;



	conf_fd = setup_config_changes(daemon);

	if (conf_fd < 0)

		goto out;



	sock_pos = fdarray__add(&fda, sock_fd, POLLIN|POLLERR|POLLHUP, 0);

	if (sock_pos < 0)

		goto out;



	file_pos = fdarray__add(&fda, conf_fd, POLLIN|POLLERR|POLLHUP, 0);

	if (file_pos < 0)

		goto out;



	signal(SIGINT, sig_handler);

	signal(SIGTERM, sig_handler);
@@ -643,6 +733,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 


			if (fda.entries[sock_pos].revents & POLLIN)

				err = handle_server_socket(daemon, sock_fd);

			if (fda.entries[file_pos].revents & POLLIN)

				err = handle_config_changes(daemon, conf_fd, &reconfig);



			if (reconfig)

				err = setup_server_config(daemon);
@@ -657,6 +749,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 


	if (sock_fd != -1)

		close(sock_fd);

	if (conf_fd != -1)

		close(conf_fd);



	pr_info("daemon exited\n");

	fclose(daemon->out);