linux-zen-desktop/tools/perf/builtin-daemon.c

// SPDX-License-Identifier: GPL-2.0
#include <internal/lib.h>
#include <subcmd/parse-options.h>
#include <api/fd/array.h>
#include <api/fs/fs.h>
#include <linux/zalloc.h>
#include <linux/string.h>
#include <linux/limits.h>
#include <string.h>
#include <sys/file.h>
#include <signal.h>
#include <stdlib.h>
#include <time.h>
#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>
#include <sys/stat.h>
#include <sys/signalfd.h>
#include <sys/wait.h>
#include <poll.h>
#include "builtin.h"
#include "perf.h"
#include "debug.h"
#include "config.h"
#include "util.h"

#define SESSION_OUTPUT  "output"
#define SESSION_CONTROL "control"
#define SESSION_ACK     "ack"

/*
 * 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 daemon_session_state {
	OK,
	RECONFIG,
	KILL,
};

struct daemon_session {
	char				*base;
	char				*name;
	char				*run;
	char				*control;
	int				 pid;
	struct list_head		 list;
	enum daemon_session_state	 state;
	time_t				 start;
};

struct daemon {
	const char		*config;
	char			*config_real;
	char			*config_base;
	const char		*csv_sep;
	const char		*base_user;
	char			*base;
	struct list_head	 sessions;
	FILE			*out;
	char			 perf[PATH_MAX];
	int			 signal_fd;
	time_t			 start;
};

static struct daemon __daemon = {
	.sessions = LIST_HEAD_INIT(__daemon.sessions),
};

static const char * const daemon_usage[] = {
	"perf daemon {start|signal|stop|ping} [<options>]",
	"perf daemon [<options>]",
	NULL
};

static volatile sig_atomic_t done;

static void sig_handler(int sig __maybe_unused)
{
	done = true;
}

static struct daemon_session *daemon__add_session(struct daemon *config, char *name)
{
	struct daemon_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 daemon_session *daemon__find_session(struct daemon *daemon, char *name)
{
	struct daemon_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 daemon_session *session;
	char name[100];

	if (get_session_name(var, name, sizeof(name) - 1))
		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 = RECONFIG;
	} else if (session->state == KILL) {
		/* Current session is defined, no action needed. */
		pr_debug("reconfig: found current session %s\n", name);
		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 = 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;

	if (!strcmp(var, "daemon.base") && !daemon->base_user) {
		daemon->base = strdup(value);
		if (!daemon->base)
			return -ENOMEM;
	}

	return 0;
}

static int check_base(struct daemon *daemon)
{
	struct stat st;

	if (!daemon->base) {
		pr_err("failed: base not defined\n");
		return -EINVAL;
	}

	if (stat(daemon->base, &st)) {
		switch (errno) {
		case EACCES:
			pr_err("failed: permission denied for '%s' base\n",
			       daemon->base);
			return -EACCES;
		case ENOENT:
			pr_err("failed: base '%s' does not exists\n",
			       daemon->base);
			return -EACCES;
		default:
			pr_err("failed: can't access base '%s': %s\n",
			       daemon->base, strerror(errno));
			return -errno;
		}
	}

	if ((st.st_mode & S_IFMT) != S_IFDIR) {
		pr_err("failed: base '%s' is not directory\n",
		       daemon->base);
		return -EINVAL;
	}

	return 0;
}

static int setup_client_config(struct daemon *daemon)
{
	struct perf_config_set *set = perf_config_set__load_file(daemon->config_real);
	int err = -ENOMEM;

	if (set) {
		err = perf_config_set(set, client_config, daemon);
		perf_config_set__delete(set);
	}

	return err ?: check_base(daemon);
}

static int setup_server_config(struct daemon *daemon)
{
	struct perf_config_set *set;
	struct daemon_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 daemon_session_state declaration.
	 */
	list_for_each_entry(session, &daemon->sessions, list)
		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 daemon_session__run(struct daemon_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->start = time(NULL);

	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);

	if (mkfifo(SESSION_CONTROL, 0600) && errno != EEXIST) {
		perror("failed: create control fifo");
		return -1;
	}

	if (mkfifo(SESSION_ACK, 0600) && errno != EEXIST) {
		perror("failed: create ack fifo");
		return -1;
	}

	scnprintf(buf, sizeof(buf), "%s record --control=fifo:%s,%s %s",
		  daemon->perf, SESSION_CONTROL, SESSION_ACK, session->run);

	argv = argv_split(buf, &argc);
	if (!argv)
		exit(-1);

	exit(execve(daemon->perf, argv, NULL));
	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;

	/*
	 * Take signal fd data as pure signal notification and check all
	 * the sessions state. The reason is that multiple signals can get
	 * coalesced in kernel and we can receive only single signal even
	 * if multiple SIGCHLD were generated.
	 */
	err = read(daemon->signal_fd, &si, sizeof(struct signalfd_siginfo));
	if (err != sizeof(struct signalfd_siginfo)) {
		pr_err("failed to read signal fd\n");
		return -1;
	}

	list_for_each_entry(session, &daemon->sessions, list) {
		if (session->pid == -1)
			continue;

		pid = waitpid(session->pid, &status, WNOHANG);
		if (pid <= 0)
			continue;

		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 0;
}

static int daemon_session__wait(struct daemon_session *session, 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 (session->pid != -1);

	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 daemon_session__control(struct daemon_session *session,
				   const char *msg, bool do_ack)
{
	struct pollfd pollfd = { .events = POLLIN, };
	char control_path[PATH_MAX];
	char ack_path[PATH_MAX];
	int control, ack = -1, len;
	char buf[20];
	int ret = -1;
	ssize_t err;

	/* open the control file */
	scnprintf(control_path, sizeof(control_path), "%s/%s",
		  session->base, SESSION_CONTROL);

	control = open(control_path, O_WRONLY|O_NONBLOCK);
	if (!control)
		return -1;