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SubjectRe: [PATCH 07/24] perf daemon: Add config file change check
Em Sun, Jan 31, 2021 at 12:48:39AM +0100, Jiri Olsa escreveu:
> Adding support to detect daemon's config file changes
> and re-read the configuration when that happens.
>
> Using inotify file descriptor pluged into the main
> fdarray object for polling.
>
> Example:
>
> # cat ~/.perfconfig
> [daemon]
> base=/opt/perfdata
>
> [session-cycles]
> run = -m 10M -e cycles --overwrite --switch-output -a
>
> Starting the daemon:
>
> # perf daemon start
>
> Check sessions:
>
> # perf daemon
> [772262:daemon] base: /opt/perfdata
> [772263:cycles] perf record -m 10M -e cycles --overwrite --switch-output -a
>
> Change '-m 10M' to '-m 20M', and check daemon log:
>
> # tail -f /opt/perfdata/output
> [2021-01-02 20:31:41.234045] daemon started (pid 772262)
> [2021-01-02 20:31:41.235072] reconfig: ruining session [cycles:772263]: -m 10M -e cycles --overwrite --switch-output -a
> [2021-01-02 20:32:08.310137] reconfig: session 'cycles' killed
> [2021-01-02 20:32:08.310847] reconfig: ruining session [cycles:772338]: -m 20M -e cycles --overwrite --switch-output -a
>
> And the session list:
>
> # perf daemon
> [772262:daemon] base: /opt/perfdata
> [772338:cycles] perf record -m 20M -e cycles --overwrite --switch-output -a
>
> Note the changed '-m 20M' option is in place.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/builtin-daemon.c | 99 +++++++++++++++++++++++++++++++++++--
> 1 file changed, 96 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
> index be2ade9967b3..d0a0a998e073 100644
> --- a/tools/perf/builtin-daemon.c
> +++ b/tools/perf/builtin-daemon.c
> @@ -10,6 +10,8 @@
> #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>
> @@ -73,6 +75,7 @@ struct session {
> struct daemon {
> const char *config;
> char *config_real;
> + char *config_base;
> const char *base_user;
> char *base;
> struct list_head sessions;
> @@ -493,6 +496,7 @@ static void daemon__free(struct daemon *daemon)
> session__remove(session);
>
> free(daemon->config_real);
> + free(daemon->config_base);
> free(daemon->base);

Please replace those with zfree()

> }
>
> @@ -535,6 +539,83 @@ static int daemon__reconfig(struct daemon *daemon)
> return 0;
> }
>
> +static int setup_config_changes(struct daemon *daemon)
> +{
> + char *basen = strdup(daemon->config_real);
> + char *dirn = strdup(daemon->config_real);
> + char *base, *dir;
> + int fd, wd;
> +
> + if (!dirn || !basen)
> + return -ENOMEM;

This may leak one of them

> +
> + fd = inotify_init1(IN_NONBLOCK|O_CLOEXEC);
> + if (fd < 0) {
> + perror("failed: inotify_init");
> + return -1;
> + }

Cool that inotify is being used here :-)

> +
> + dir = dirname(dirn);
> + base = basename(basen);
> + pr_debug("config file: %s, dir: %s\n", base, dir);
> +
> + wd = inotify_add_watch(fd, dir, IN_CLOSE_WRITE);
> + if (wd >= 0) {
> + daemon->config_base = strdup(base);
> + if (!daemon->config_base) {
> + close(fd);
> + wd = -1;
> + }
> + } else {
> + perror("failed: inotify_add_watch");
> + }
> +
> + free(basen);
> + free(dirn);
> + return wd < 0 ? -1 : fd;
> +}
> +
> +static bool process_inotify_event(struct daemon *daemon, char *buf, ssize_t len)
> +{
> + char *p = buf;
> +
> + while (p < (buf + len)) {
> + struct inotify_event *event = (struct inotify_event *) p;
> +
> + /*
> + * We monitor config directory, check if our
> + * config file was changes.
> + */
> + if ((event->mask & IN_CLOSE_WRITE) &&
> + !(event->mask & IN_ISDIR)) {
> + if (!strcmp(event->name, daemon->config_base))
> + return true;
> + }
> + p += sizeof(*event) + event->len;
> + }
> + return false;
> +}
> +
> +static int handle_config_changes(struct daemon *daemon, int conf_fd,
> + bool *config_changed)
> +{
> + char buf[4096];
> + ssize_t len;
> +
> + while (!(*config_changed)) {
> + len = read(conf_fd, buf, sizeof(buf));
> + if (len == -1) {
> + if (errno != EAGAIN) {
> + perror("failed: read");
> + return -1;
> + }
> + return 0;
> + }
> + *config_changed = process_inotify_event(daemon, buf, len);
> + }
> + return 0;
> +}
> +
> static int setup_config(struct daemon *daemon)
> {
> if (daemon->base_user) {
> @@ -569,8 +650,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
> OPT_PARENT(parent_options),
> OPT_END()
> };
> - int sock_fd = -1;
> - int sock_pos;
> + int sock_fd = -1, conf_fd = -1;
> + int sock_pos, file_pos;
> struct fdarray fda;
> int err = 0;
>
> @@ -591,16 +672,24 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
>
> pr_info("daemon started (pid %d)\n", getpid());
>
> - fdarray__init(&fda, 1);
> + fdarray__init(&fda, 2);
>
> sock_fd = setup_server_socket(daemon);
> if (sock_fd < 0)
> goto out;
>
> + conf_fd = setup_config_changes(daemon);
> + if (conf_fd < 0)
> + goto out;
> +
> sock_pos = fdarray__add(&fda, sock_fd, POLLIN|POLLERR|POLLHUP, 0);
> if (sock_pos < 0)
> goto out;
>
> + file_pos = fdarray__add(&fda, conf_fd, POLLIN|POLLERR|POLLHUP, 0);
> + if (file_pos < 0)
> + goto out;
> +
> signal(SIGINT, sig_handler);
> signal(SIGTERM, sig_handler);
>
> @@ -612,6 +701,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
>
> if (fda.entries[sock_pos].revents & POLLIN)
> err = handle_server_socket(daemon, sock_fd);
> + if (fda.entries[file_pos].revents & POLLIN)
> + err = handle_config_changes(daemon, conf_fd, &reconfig);
>
> if (reconfig)
> err = setup_server_config(daemon);
> @@ -625,6 +716,8 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
>
> if (sock_fd != -1)
> close(sock_fd);
> + if (conf_fd != -1)
> + close(conf_fd);
>
> pr_info("daemon exited\n");
> fclose(daemon->out);
> --
> 2.29.2
>

--

- Arnaldo

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