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Date:   Thu, 10 Sep 2020 10:59:26 +0200
From:   Jiri Olsa <jolsa@redhat.com>
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Stephane Eranian <eranian@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Andi Kleen <andi@firstfloor.org>,
        Ian Rogers <irogers@google.com>
Subject: Re: [PATCH 1/4] perf evsel: Add evsel__clone() function
Message-ID: <20200910085926.GC1627030@krava>
References: <20200908044228.61197-1-namhyung@kernel.org>
 <20200908044228.61197-2-namhyung@kernel.org>
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On Tue, Sep 08, 2020 at 01:42:25PM +0900, Namhyung Kim wrote:
> The evsel__clone() is to create an exactly same evsel from same
> attributes.  Note that metric events will be handled by later patch.
> 
> It will be used by perf stat to generate separate events for each
> cgroup.
> 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/util/evsel.c | 57 +++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/evsel.h |  1 +
>  2 files changed, 58 insertions(+)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index fd865002cbbd..4f50f9499973 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -331,6 +331,63 @@ struct evsel *evsel__new_cycles(bool precise)
>  	goto out;
>  }
>  
> +/**
> + * evsel__clone - create a new evsel copied from @orig
> + * @orig: original evsel
> + *
> + * The assumption is that @orig is not configured nor opened yet.
> + * So we only care about the attributes that can be set while it's parsed.
> + */
> +struct evsel *evsel__clone(struct evsel *orig)
> +{
> +	struct evsel *evsel;
> +	struct evsel_config_term *pos, *tmp;
> +
> +	BUG_ON(orig->core.fd);
> +
> +	evsel = evsel__new(&orig->core.attr);
> +	if (evsel == NULL)
> +		return NULL;
> +
> +	*evsel = *orig;

this seems wild ;-) I saw that assumption above,
but I wonder we could add some check or zero/init
the rest of the fields fields

jirka