linux-kernel - Re: [PATCH] perf trace: Move SIGCHLD handler init to trace_

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Date:   Fri, 7 Jan 2022 15:57:28 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Christy Lee <christyc.y.lee@...il.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] perf trace: Move SIGCHLD handler init to trace__run

Em Thu, Jan 06, 2022 at 11:20:30PM +0100, Jiri Olsa escreveu:
> When running perf trace with bpf object like:
>   # perf trace -e openat,/.../tools/perf/examples/bpf/hello.c
> 
> the event parsing eventually calls llvm__get_kbuild_opts function
> that runs script and that ends up with SIGCHLD delivered to perf
> trace handler, which assumes the workload process is done and quits
> perf trace.
> 
> Moving the SIGCHLD handler setup directly to trace__run, where the
> event is parsed and object already compiled.


Thanks, reproduced the problem without the patch, applied, tested again,
works.

- Arnaldo

 
> Cc: Christy Lee <christyc.y.lee@...il.com>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/builtin-trace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 94d62a92f1a1..4282ef9ec354 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -3925,6 +3925,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv)
>  	bool draining = false;
>  
>  	trace->live = true;
> +	signal(SIGCHLD, sig_handler);
>  
>  	if (!trace->raw_augmented_syscalls) {
>  		if (trace->trace_syscalls && trace__add_syscall_newtp(trace))
> @@ -4876,7 +4877,6 @@ 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();
> -- 
> 2.33.1

-- 

- Arnaldo