linux-kernel - RE: [PATCH RFC V4 1/6] perf tools: lock to protect namespaces and comm list

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Message-ID: <37D7C6CF3E00A74B8858931C1DB2F077537CD725@SHSMSX103.ccr.corp.intel.com>
Date:   Mon, 2 Oct 2017 19:14:10 +0000
From:   "Liang, Kan" <kan.liang@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jolsa@...nel.org" <jolsa@...nel.org>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "Hunter, Adrian" <adrian.hunter@...el.com>,
        "Odzioba, Lukasz" <lukasz.odzioba@...el.com>,
        "wangnan0@...wei.com" <wangnan0@...wei.com>,
        "hekuang@...wei.com" <hekuang@...wei.com>,
        "ast@...nel.org" <ast@...nel.org>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: RE: [PATCH RFC V4 1/6] perf tools: lock to protect namespaces and
 comm list

> Em Fri, Sep 29, 2017 at 07:47:52AM -0700, kan.liang@...el.com escreveu:
> > From: Kan Liang <kan.liang@...el.com>
> >
> > Add two locks to protect namespaces_list and comm_list.
> >
> > The lock is only needed for multithreaded code, so using mutex
> > wrappers provided by perf tool.
> >
> > Not all the comm_list/namespaces_list accessing are protected, e.g.
> > thread__exec_comm. Because the multithread code for perf top event
> > synthesizing does not touch them. They don't need a lock.
> 
> They don't need a lock _now_, ok I think we can proceed that way, this cset
> should serve as a warning to people working in further multithreading perf.
> 

Do I need to add some comments in the code to give a warning?

Thanks,
Kan