* Re: [PATCH] perf trace: Fix race in signal handling
[not found] <20210302144120.17362-1-mpetlan@redhat.com>
@ 2021-03-05 17:16 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; only message in thread
From: Arnaldo Carvalho de Melo @ 2021-03-05 17:16 UTC (permalink / raw)
To: Michael Petlan; +Cc: acme, linux-perf-users, jolsa, Linux Kernel Mailing List
Em Tue, Mar 02, 2021 at 03:41:20PM +0100, Michael Petlan escreveu:
> Since a lot of stuff happens before the SIGINT signal handler is registered
> (scanning /proc/*, etc.), on bigger systems, such as Cavium Sabre CN99xx,
> it may happen that first interrupt signal is lost and perf isn't correctly
> terminated.
>
> The reproduction code might look like the following:
>
> perf trace -a &
> PERF_PID=$!
> sleep 4
> kill -INT $PERF_PID
>
> The issue has been found on a CN99xx machine with RHEL-8 and the patch fixes
> it by registering the signal handlers earlier in the init stage.
Thanks, applied.
- Arnaldo
> Suggested-by: Jiri Olsa <jolsa@redhat.com>
> Signed-off-by: Michael Petlan <mpetlan@redhat.com>
> Tested-by: Michael Petlan <mpetlan@redhat.com>
> ---
> tools/perf/builtin-trace.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 85b6a46e85b6..7ec18ff57fc4 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -3964,9 +3964,6 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
>
> evlist__config(evlist, &trace->opts, &callchain_param);
>
> - signal(SIGCHLD, sig_handler);
> - signal(SIGINT, sig_handler);
> -
> if (forks) {
> err = evlist__prepare_workload(evlist, &trace->opts.target, argv, false, NULL);
> if (err < 0) {
> @@ -4827,6 +4824,8 @@ int cmd_trace(int argc, const char **argv)
>
> signal(SIGSEGV, sighandler_dump_stack);
> signal(SIGFPE, sighandler_dump_stack);
> + signal(SIGCHLD, sig_handler);
> + signal(SIGINT, sig_handler);
>
> trace.evlist = evlist__new();
> trace.sctbl = syscalltbl__new();
> --
> 2.18.4
>
--
- Arnaldo
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