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Date:   Sat, 27 Aug 2022 10:11:19 +0300
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Subject: Re: [PATCH v3 09/18] perf ui: Update use of pthread mutex
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To:     Ian Rogers <irogers@google.com>, Namhyung Kim <namhyung@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
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From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
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On 26/08/22 23:52, Ian Rogers wrote:
> On Fri, Aug 26, 2022 at 1:40 PM Namhyung Kim <namhyung@kernel.org> wrote:
>>
>> On Fri, Aug 26, 2022 at 12:21 PM Adrian Hunter <adrian.hunter@intel.com> wrote:
>>>
>>> On 26/08/22 22:00, Namhyung Kim wrote:
>>>> On Fri, Aug 26, 2022 at 11:53 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>>>>> Below seems adequate for now, at least logically, but maybe it
>>>>> would confuse clang thread-safety analysis?
>>>>
>>>> I think it's not just about locks, the exit_browser should bail out early
>>>> if the setup code was not called.
>>>
>>> In those cases, use_browser is 0 or -1 unless someone has inserted
>>> an invalid perf config like "tui.script=on" or "gtk.script=on".
>>> So currently, in cases where exit_browser() is called without
>>> setup_browser(), it does nothing.  Which means it is only the
>>> unconditional mutex_destroy() that needs to be conditional.
>>
>> Yeah there's a possibility that it can be called with > 0 use_browser
>> on some broken config or something.  So I think it's safer and better
>> for future changes.
> 
> I'd thought about a:
> static bool ui__lock_initialized;
> but the issue is shouldn't it be atomic?

No, it is only accessed from the main thread.