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

From: Arnaldo Carvalho de Melo
Date: Wed Feb 03 2021 - 16:13:10 EST

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Next in thread: Jiri Olsa: "Re: [PATCH 06/24] perf daemon: Add config file support"
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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@xxxxxxxxxx>
> ---
> 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

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