linux-kernel - Re: [PATCH 02/31] perf tools: Don't set cmdline_group

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Date:	Tue, 1 Sep 2015 12:38:48 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:	Jiri Olsa <jolsa@...nel.org>, Wang Nan <wangnan0@...wei.com>,
	mingo@...nel.org, ast@...mgrid.com, linux-kernel@...r.kernel.org,
	lizefan@...wei.com, pi3orama@....com,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH 02/31] perf tools: Don't set cmdline_group_boundary if no
 evsel is collected

On Mon, Aug 31, 2015 at 04:20:03PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sat, Aug 29, 2015 at 04:21:36AM +0000, Wang Nan escreveu:
> > If parse_events__scanner() collects no entry, perf_evlist__last(evlist)
> > is invalid. Then setting of cmdline_group_boundary touches invalid.
> > 
> > It could happend in currect BPF implementation. See [1]. Although it
> > can be fixed, for safety reason it whould be better to introduce this
> > check.
> > 
> > Instead of checking number of entries, check data.list instead, so we
> > can add dummy evsel here.
> 
> Event parsing fixes should have Jiri Olsa on the CC list, Jiri, is this
> ok?
> 
> From what I can see it looks Ok, my question, just from looking at this
> patch, is if it is valid to get to this point with an empty data.list,
> i.e. was it ever possible and this is a bug irrespective of eBPF?

good point, I believe it's either fail or event(s) added to the list
I haven't checked how's eBPF connected with event parsing, is there a
git tree I could check?

thanks,
jirka
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