Add 'lock' file under daemon base and flock it, so only one perf daemon can run on top of it.
# perf daemon --config ./config.daemon # perf daemon --config ./config.daemon failed: another perf daemon (pid 369675) owns /opt/perfdata Signed-off-by: Jiri Olsa <[email protected]> --- tools/perf/builtin-daemon.c | 43 +++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c index 855fed2fe364..1bd5432a57a3 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> @@ -639,6 +640,42 @@ 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, 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; @@ -653,6 +690,9 @@ static int go_background(struct daemon *daemon) if (setsid() < 0) return -1; + if (check_lock(daemon)) + return -1; + umask(0); if (chdir(daemon->base)) { @@ -704,6 +744,9 @@ static int __cmd_daemon(struct daemon *daemon, bool foreground, const char *conf if (setup_server_config(daemon)) return -1; + if (foreground && check_lock(daemon)) + return -1; + if (!foreground && go_background(daemon)) return -1; -- 2.26.2
