linux-kernel - Re: [PATCH perf/urgent] perf tools: Fix crash on synthesizing the unit

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Date:   Mon, 12 Nov 2018 08:40:53 -0800
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Adam Lee <leeadamrobert@...il.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH perf/urgent] perf tools: Fix crash on synthesizing the
 unit

Em Mon, Nov 12, 2018 at 02:00:12PM +0100, Jiri Olsa escreveu:
> Adam reported a record command crash for simple session like:
>   $ perf record -e cpu-clock ls

Thanks, tested, confirmed it fixes the problem, applied.

- Arnaldo
 
> with following backtrace:
> 
>   Program received signal SIGSEGV, Segmentation fault.
>   3543            ev = event_update_event__new(size + 1, PERF_EVENT_UPDATE__UNIT, evsel->id[0]);
>   (gdb) bt
>   #0  perf_event__synthesize_event_update_unit
>   #1  0x000000000051e469 in perf_event__synthesize_extra_attr
>   #2  0x00000000004445cb in record__synthesize
>   #3  0x0000000000444bc5 in __cmd_record
>   ...
> 
> We synthesize an update event that needs to touch the evsel id array, which is
> not defined at that time. Fixing this by forcing the id allocation for events
> with their unit defined.
> 
> Reflecting possible read_format ID bit in the attr tests.
> 
> Cc: Adam Lee <leeadamrobert@...il.com>
> Reported-by: Yongxin Liu <yongxin.liu@...look.com>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201477
> Fixes: bfd8f72c2778 ("perf record: Synthesize unit/scale/... in event update")
> Link: http://lkml.kernel.org/n/tip-hmt7oavo3w97btxl8sfq8n0i@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/tests/attr/base-record | 2 +-
>  tools/perf/util/evsel.c           | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/tests/attr/base-record b/tools/perf/tests/attr/base-record
> index 37940665f736..efd0157b9d22 100644
> --- a/tools/perf/tests/attr/base-record
> +++ b/tools/perf/tests/attr/base-record
> @@ -9,7 +9,7 @@ size=112
>  config=0
>  sample_period=*
>  sample_type=263
> -read_format=0
> +read_format=0|4
>  disabled=1
>  inherit=1
>  pinned=0
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index d37bb1566cd9..dbc0466db368 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1092,7 +1092,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
>  		attr->exclude_user   = 1;
>  	}
>  
> -	if (evsel->own_cpus)
> +	if (evsel->own_cpus || evsel->unit)
>  		evsel->attr.read_format |= PERF_FORMAT_ID;
>  
>  	/*
> -- 
> 2.17.2