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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Sun, Jan 31, 2021 at 12:48:38AM +0100, Jiri Olsa escreveu:
> 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));

	
	struct 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*

add space after type name

   static struct session *

And we could have it in the same line:

  static struct session *daemon__find_session(struct daemon *daemon, char *name)

> +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)))

Good , using sizeof () :)

> +		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 else uses {}, if should too

> +		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);

zfree() so that if there is some dangling pointer to session, we'll get
NULL derefs

> +	free(session);
> +}
> +
> +static void session__remove(struct session *session)
> +{
> +	list_del(&session->list);

list_del_init

> +	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);

Wouldn't be better to have:

	 list_for_each_entry_safe(session, h, &daemon->sessions, list) {
	 	list_del_init(&session->list);
		session__free(session);
	 }

Because naming that function "session__remove()" one thinks it is being
removed from some data structure, but not that it is being as well
deleted.

Please rename session__free() to session__delete() to keep it consistent
with other places.

> +
>  	free(daemon->config_real);
>  	free(daemon->base);
>  }
>  
>  static void daemon__exit(struct daemon *daemon)
>  {
> +	daemon__kill(daemon);
>  	daemon__free(daemon);

Ditto for daemon__free(): please rename it to daemon__delete()

>  }
>  
> +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
> 

-- 

- Arnaldo