linux-kernel - Re: [PATCH v3 11/18] perf dso: Update use of pthread mutex

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Date:   Fri, 26 Aug 2022 10:46:05 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Darren Hart <dvhart@...radead.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        André Almeida <andrealmeid@...lia.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, Weiguo Li <liwg06@...mail.com>,
        Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
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        Kajol Jain <kjain@...ux.ibm.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
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        Andi Kleen <ak@...ux.intel.com>,
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        Zechuan Chen <chenzechuan1@...wei.com>,
        Jason Wang <wangborong@...rlc.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Remi Bernon <rbernon@...eweavers.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v3 11/18] perf dso: Update use of pthread mutex

On Fri, Aug 26, 2022 at 10:34 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 26/08/22 19:05, Ian Rogers wrote:
> > On Fri, Aug 26, 2022 at 3:37 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
> >>
> >> On 24/08/22 18:38, Ian Rogers wrote:
> >>> Switch to the use of mutex wrappers that provide better error checking.
> >>>
> >>> Signed-off-by: Ian Rogers <irogers@...gle.com>
> >>> ---
> >>>  tools/perf/util/dso.c    | 12 ++++++------
> >>
> >> Some not done yet
> >>
> >> $ grep -i pthread_mut tools/perf/util/dso.c
> >> static pthread_mutex_t dso__data_open_lock = PTHREAD_MUTEX_INITIALIZER;
> >>         pthread_mutex_lock(&dso__data_open_lock);
> >>         pthread_mutex_unlock(&dso__data_open_lock);
> >>         if (pthread_mutex_lock(&dso__data_open_lock) < 0)
> >>                 pthread_mutex_unlock(&dso__data_open_lock);
> >>         pthread_mutex_unlock(&dso__data_open_lock);
> >>         pthread_mutex_lock(&dso__data_open_lock);
> >>         pthread_mutex_unlock(&dso__data_open_lock);
> >>         pthread_mutex_lock(&dso__data_open_lock);
> >>         pthread_mutex_unlock(&dso__data_open_lock);
> >
> > Yes, these are all solely dso__data_open_lock that lacks any clear
> > init/exit code to place the initialization/destruction hooks onto. I
> > don't plan to alter these in this patch set.
>
> Perhaps that could be explained in the change log.
>
> But why not just add init / exit code.  Could be called out
> of main(), or maybe use __attribute__((constructor)) /
> __attribute__((destructor))

Because the lock is global and not part of the dso.

Thanks,
Ian