Commit 12c1a415 authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
Browse files

perf daemon: Add signalfd support 



Use a signalfd fd to track SIGCHLD signals as notifications for perf
session termination.

This way we don't need to actively check for child status, being
notified if there's change.

Suggested-by: default avatarAlexei Budankov <abudankov@huawei.com>
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.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/20210208200908.1019149-10-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 88adb119

tools/perf/builtin-daemon.c

+155 −6
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <string.h>

#include <signal.h>

#include <stdlib.h>

#include <time.h>

#include <stdio.h>

#include <unistd.h>

#include <errno.h>
@@ -18,6 +19,8 @@ 
#include <sys/socket.h>

#include <sys/un.h>

#include <sys/stat.h>

#include <sys/signalfd.h>

#include <sys/wait.h>

#include <poll.h>

#include <sys/stat.h>

#include "builtin.h"
@@ -83,6 +86,7 @@ struct daemon { 
	struct list_head	 sessions;

	FILE			*out;

	char			 perf[PATH_MAX];

	int			 signal_fd;

};



static struct daemon __daemon = {
@@ -368,6 +372,116 @@ static int daemon_session__run(struct daemon_session *session, 
	return -1;

}



static pid_t handle_signalfd(struct daemon *daemon)

{

	struct daemon_session *session;

	struct signalfd_siginfo si;

	ssize_t err;

	int status;

	pid_t pid;



	err = read(daemon->signal_fd, &si, sizeof(struct signalfd_siginfo));

	if (err != sizeof(struct signalfd_siginfo))

		return -1;



	list_for_each_entry(session, &daemon->sessions, list) {



		if (session->pid != (int) si.ssi_pid)

			continue;



		pid = waitpid(session->pid, &status, 0);

		if (pid == session->pid) {

			if (WIFEXITED(status)) {

				pr_info("session '%s' exited, status=%d\n",

					session->name, WEXITSTATUS(status));

			} else if (WIFSIGNALED(status)) {

				pr_info("session '%s' killed (signal %d)\n",

					session->name, WTERMSIG(status));

			} else if (WIFSTOPPED(status)) {

				pr_info("session '%s' stopped (signal %d)\n",

					session->name, WSTOPSIG(status));

			} else {

				pr_info("session '%s' Unexpected status (0x%x)\n",

					session->name, status);

			}

		}



		session->state = KILL;

		session->pid = -1;

		return pid;

	}



	return 0;

}



static int daemon_session__wait(struct daemon_session *session, struct daemon *daemon,

				int secs)

{

	struct pollfd pollfd = {

		.fd	= daemon->signal_fd,

		.events	= POLLIN,

	};

	pid_t wpid = 0, pid = session->pid;

	time_t start;



	start = time(NULL);



	do {

		int err = poll(&pollfd, 1, 1000);



		if (err > 0) {

			wpid = handle_signalfd(daemon);

		} else if (err < 0) {

			perror("failed: poll\n");

			return -1;

		}



		if (start + secs < time(NULL))

			return -1;

	} while (wpid != pid);



	return 0;

}



static bool daemon__has_alive_session(struct daemon *daemon)

{

	struct daemon_session *session;



	list_for_each_entry(session, &daemon->sessions, list) {

		if (session->pid != -1)

			return true;

	}



	return false;

}



static int daemon__wait(struct daemon *daemon, int secs)

{

	struct pollfd pollfd = {

		.fd	= daemon->signal_fd,

		.events	= POLLIN,

	};

	time_t start;



	start = time(NULL);



	do {

		int err = poll(&pollfd, 1, 1000);



		if (err > 0) {

			handle_signalfd(daemon);

		} else if (err < 0) {

			perror("failed: poll\n");

			return -1;

		}



		if (start + secs < time(NULL))

			return -1;

	} while (daemon__has_alive_session(daemon));



	return 0;

}



static int setup_server_socket(struct daemon *daemon)

{

	struct sockaddr_un addr;
@@ -493,9 +607,14 @@ static int daemon_session__signal(struct daemon_session *session, int sig) 
	return kill(session->pid, sig);

}



static void daemon_session__kill(struct daemon_session *session)

static void daemon_session__kill(struct daemon_session *session,

				 struct daemon *daemon)

{

	daemon_session__signal(session, SIGTERM);

	if (daemon_session__wait(session, daemon, 10)) {

		daemon_session__signal(session, SIGKILL);

		daemon_session__wait(session, daemon, 10);

	}

}



static void daemon__signal(struct daemon *daemon, int sig)
@@ -523,6 +642,10 @@ static void daemon_session__remove(struct daemon_session *session) 
static void daemon__kill(struct daemon *daemon)

{

	daemon__signal(daemon, SIGTERM);

	if (daemon__wait(daemon, 10)) {

		daemon__signal(daemon, SIGKILL);

		daemon__wait(daemon, 10);

	}

}



static void daemon__exit(struct daemon *daemon)
@@ -549,7 +672,7 @@ static int daemon__reconfig(struct daemon *daemon) 
		/* Remove session. */

		if (session->state == KILL) {

			if (session->pid > 0) {

				daemon_session__kill(session);

				daemon_session__kill(session, daemon);

				pr_info("reconfig: session '%s' killed\n", session->name);

			}

			daemon_session__remove(session);
@@ -558,7 +681,7 @@ static int daemon__reconfig(struct daemon *daemon) 


		/* Reconfig session. */

		if (session->pid > 0) {

			daemon_session__kill(session);

			daemon_session__kill(session, daemon);

			pr_info("reconfig: session '%s' killed\n", session->name);

		}

		if (daemon_session__run(session, daemon))
@@ -724,6 +847,20 @@ static int go_background(struct daemon *daemon) 
	return 0;

}



static int setup_signalfd(struct daemon *daemon)

{

	sigset_t mask;



	sigemptyset(&mask);

	sigaddset(&mask, SIGCHLD);



	if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1)

		return -1;



	daemon->signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);

	return daemon->signal_fd;

}



static int __cmd_start(struct daemon *daemon, struct option parent_options[],

		       int argc, const char **argv)

{
@@ -733,8 +870,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
		OPT_PARENT(parent_options),

		OPT_END()

	};

	int sock_fd = -1, conf_fd = -1;

	int sock_pos, file_pos;

	int sock_fd = -1, conf_fd = -1, signal_fd = -1;

	int sock_pos, file_pos, signal_pos;

	struct fdarray fda;

	int err = 0;
@@ -766,7 +903,7 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 


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



	fdarray__init(&fda, 2);

	fdarray__init(&fda, 3);



	sock_fd = setup_server_socket(daemon);

	if (sock_fd < 0)
@@ -776,6 +913,10 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
	if (conf_fd < 0)

		goto out;



	signal_fd = setup_signalfd(daemon);

	if (signal_fd < 0)

		goto out;



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

	if (sock_pos < 0)

		goto out;
@@ -784,6 +925,10 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
	if (file_pos < 0)

		goto out;



	signal_pos = fdarray__add(&fda, signal_fd, POLLIN|POLLERR|POLLHUP, 0);

	if (signal_pos < 0)

		goto out;



	signal(SIGINT, sig_handler);

	signal(SIGTERM, sig_handler);
@@ -797,6 +942,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
				err = handle_server_socket(daemon, sock_fd);

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

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

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

				err = handle_signalfd(daemon) < 0;



			if (reconfig)

				err = setup_server_config(daemon);
@@ -813,6 +960,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], 
		close(sock_fd);

	if (conf_fd != -1)

		close(conf_fd);

	if (conf_fd != -1)

		close(signal_fd);



	pr_info("daemon exited\n");

	fclose(daemon->out);