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Date: Wed, 22 Jun 2016 10:40:51 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Wang Nan <wangnan0@huawei.com>
Cc: Nilay Vaish <nilayvaish@gmail.com>,
        Linux Kernel list <linux-kernel@vger.kernel.org>, pi3orama@163.com,
        He Kuang <hekuang@huawei.com>, Jiri Olsa <jolsa@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>
Subject: Re: [PATCH v9 1/8] perf evlist: Introduce aux evlist
Message-ID: <20160622134051.GI4213@kernel.org>
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Em Wed, Jun 22, 2016 at 08:17:02AM -0500, Nilay Vaish escreveu:
> On 22 June 2016 at 04:08, Wang Nan <wangnan0@huawei.com> wrote:
> > +struct perf_evlist *perf_evlist__new_aux(struct perf_evlist *parent)
> > +{
> > +       struct perf_evlist *evlist;
> > +
> > +       if (perf_evlist__is_aux(parent)) {
> > +               pr_err("Internal error: create aux evlist from another aux evlist\n");
> > +               return NULL;
> > +       }
> > +
> > +       evlist = zalloc(sizeof(*evlist));
> > +       if (!evlist)
> > +               return NULL;
> > +
> > +       perf_evlist__init(evlist, parent->cpus, parent->threads);
> > +       evlist->parent = parent->parent;
> 
> A very minor suggestion.  I think evlist->parent  should be set to
> 'parent' and not 'parent->parent'.  I agree the two values are equal,
> but setting to parent->parent just does not seem right.

I felt like that, thought I was missing something, which is always a bad
feeling when processing a patch... So, Wang, does that have some value
we are not seeing?

I thought about the possibility of adding an aux2 to an aux1 evlist and
that making aux2 have the same parent as aux1, but that is checked on
that pr_err() test...

- Arnaldo