Em Sat, Dec 12, 2020 at 11:43:57AM +0100, Jiri Olsa escreveu:
> 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
So the way to disambiguate is the "daemon base"?
- Arnaldo
> Signed-off-by: Jiri Olsa <jo...@kernel.org>
> ---
> 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
>
--
- Arnaldo
