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SubjectRe: [PATCH 09/24] perf daemon: Add signalfd support
Em Sun, Jan 31, 2021 at 12:48:41AM +0100, Jiri Olsa escreveu:
> Using signalfd fd for tracking SIGCHLD signals as
> notification for perf session termination.
>
> This way we don't need to actively check for child
> status, but we are notified if there's change.
>
> Suggested-by: Alexei Budankov <abudankov@huawei.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/builtin-daemon.c | 147 ++++++++++++++++++++++++++++++++++--
> 1 file changed, 141 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
> index 324666058842..69d3af70b642 100644
> --- a/tools/perf/builtin-daemon.c
> +++ b/tools/perf/builtin-daemon.c
> @@ -7,6 +7,7 @@
> #include <string.h>
> #include <signal.h>
> #include <stdlib.h>
> +#include <time.h>
> #include <stdio.h>
> #include <unistd.h>
> #include <errno.h>
> @@ -16,6 +17,8 @@
> #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"
> @@ -81,6 +84,7 @@ struct daemon {
> struct list_head sessions;
> FILE *out;
> char perf[PATH_MAX];
> + int signal_fd;
> };
>
> static struct daemon __daemon = {
> @@ -351,6 +355,103 @@ static int session__run(struct session *session, struct daemon *daemon)
> return -1;
> }
>
> +static pid_t handle_signalfd(struct daemon *daemon)
> +{
> + struct signalfd_siginfo si;
> + struct session *session;
> + ssize_t err;
> + int status;
> + pid_t pid;
> +
> + err = read(daemon->signal_fd, &si, sizeof(struct signalfd_siginfo));


I saw these and recalled we have a readn() function, shouldn't we be
usint it in this series?

Its even in tools/lib/perf/lib.c

> + 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 = SESSION_STATE__KILL;
> + session->pid = -1;
> + return pid;
> + }
> +
> + return 0;
> +}
> +
> +static int session__wait(struct 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);


time_t start = time(NULL);
> +
> + do {
> + if (poll(&pollfd, 1, 1000))
> + wpid = handle_signalfd(daemon);

Shouldn't we check for -1 and handle that differently?

> +
> + if (start + secs < time(NULL))
> + return -1;
> + } while (wpid != pid);
> +
> + return 0;
> +}
> +
> +static bool daemon__has_alive_session(struct daemon *daemon)
> +{
> + struct 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 {
> + if (poll(&pollfd, 1, 1000))
> + handle_signalfd(daemon);

ditto

> +
> + 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;
> @@ -456,9 +557,13 @@ static int session__signal(struct session *session, int sig)
> return kill(session->pid, sig);
> }
>
> -static void session__kill(struct session *session)
> +static void session__kill(struct session *session, struct daemon *daemon)
> {
> session__signal(session, SIGTERM);
> + if (session__wait(session, daemon, 10)) {
> + session__signal(session, SIGKILL);
> + session__wait(session, daemon, 10);
> + }
> }
>
> static void daemon__signal(struct daemon *daemon, int sig)
> @@ -486,6 +591,10 @@ static void session__remove(struct 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__free(struct daemon *daemon)
> @@ -523,7 +632,7 @@ static int daemon__reconfig(struct daemon *daemon)
> /* Remove session. */
> if (session->state == SESSION_STATE__KILL) {
> if (session->pid > 0) {
> - session__kill(session);
> + session__kill(session, daemon);
> pr_info("reconfig: session '%s' killed\n", session->name);
> }
> session__remove(session);
> @@ -532,7 +641,7 @@ static int daemon__reconfig(struct daemon *daemon)
>
> /* Reconfig session. */
> if (session->pid > 0) {
> - session__kill(session);
> + session__kill(session, daemon);
> pr_info("reconfig: session '%s' killed\n", session->name);
> }
> if (session__run(session, daemon))
> @@ -690,6 +799,20 @@ 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)
> {
> @@ -699,8 +822,8 @@ 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;
>
> @@ -732,7 +855,7 @@ 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)
> @@ -742,6 +865,10 @@ 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;
> @@ -750,6 +877,10 @@ 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);
>
> @@ -763,6 +894,8 @@ 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);
> @@ -778,6 +911,8 @@ 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);
> --
> 2.29.2
>

--

- Arnaldo

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