Messages in this thread Patch in this message | | | From | Jiri Olsa <> | Subject | [PATCH 12/22] perf daemon: Allow only one daemon over base directory | Date | Sat, 2 Jan 2021 23:04:31 +0100 |
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Add 'lock' file under daemon base and flock it, so only one perf daemon can run on top of it.
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
Starting the daemon:
# perf daemon start
And try once more:
# perf daemon start failed: another perf daemon (pid 775594) owns /opt/perfdata
will end up with an error, because there's already one running on top of /opt/perfdata.
Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- tools/perf/builtin-daemon.c | 49 +++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+)
diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c index 45748bb471ec..1982eedd3f3f 100644 --- a/tools/perf/builtin-daemon.c +++ b/tools/perf/builtin-daemon.c @@ -8,6 +8,7 @@ #include <string.h> #include <sys/types.h> #include <sys/wait.h> +#include <sys/file.h> #include <signal.h> #include <stdlib.h> #include <time.h> @@ -562,12 +563,18 @@ static int cmd_session_list(struct daemon *daemon, union cmd *cmd, FILE *out) /* output */ csv_sep, daemon->base, SESSION_OUTPUT); + fprintf(out, "%c%s/%s", + /* lock */ + csv_sep, daemon->base, "lock"); + fprintf(out, "\n"); } else { fprintf(out, "[%d:daemon] base: %s\n", getpid(), daemon->base); if (cmd->list.verbose) { fprintf(out, " output: %s/%s\n", daemon->base, SESSION_OUTPUT); + fprintf(out, " lock: %s/lock\n", + daemon->base); } } @@ -761,6 +768,42 @@ static int handle_config_changes(struct daemon *daemon, int conf_fd, return 0; } +static int check_lock(struct daemon *daemon) +{ + char path[PATH_MAX]; + char buf[20]; + int fd, pid; + ssize_t len; + + scnprintf(path, sizeof(path), "%s/lock", daemon->base); + + fd = open(path, O_RDWR|O_CREAT|O_CLOEXEC, 0640); + if (fd < 0) + return -1; + + if (lockf(fd, F_TLOCK, 0) < 0) { + filename__read_int(path, &pid); + fprintf(stderr, "failed: another perf daemon (pid %d) owns %s\n", + pid, daemon->base); + return -1; + } + + scnprintf(buf, sizeof(buf), "%d", getpid()); + len = strlen(buf); + + if (write(fd, buf, len) != len) { + perror("write failed"); + return -1; + } + + if (ftruncate(fd, len)) { + perror("ftruncate failed"); + return -1; + } + + return 0; +} + static int go_background(struct daemon *daemon) { int pid, fd; @@ -775,6 +818,9 @@ static int go_background(struct daemon *daemon) if (setsid() < 0) return -1; + if (check_lock(daemon)) + return -1; + umask(0); if (chdir(daemon->base)) { @@ -861,6 +907,9 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[], if (setup_server_config(daemon)) return -1; + if (foreground && check_lock(daemon)) + return -1; + if (!foreground && go_background(daemon)) return -1; -- 2.26.2
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