linux-kernel - Re: [PATCH v3 09/18] perf ui: Update use of pthread mutex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAP-5=fWvf66snfmUfaTQ6BZ9EmsmBs0PUT8PAfehW74bnEE5nQ@mail.gmail.com>
Date:   Fri, 26 Aug 2022 13:52:07 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        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>,
        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>,
        Dario Petrillo <dario.pk1@...il.com>,
        Hewenliang <hewenliang4@...wei.com>,
        yaowenbin <yaowenbin1@...wei.com>,
        Wenyu Liu <liuwenyu7@...wei.com>,
        Song Liu <songliubraving@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Dave Marchevsky <davemarchevsky@...com>,
        Leo Yan <leo.yan@...aro.org>,
        Kim Phillips <kim.phillips@....com>,
        Pavithra Gurushankar <gpavithrasha@...il.com>,
        Alexandre Truong <alexandre.truong@....com>,
        Quentin Monnet <quentin@...valent.com>,
        William Cohen <wcohen@...hat.com>,
        Andres Freund <andres@...razel.de>,
        Martin Liška <mliska@...e.cz>,
        Colin Ian King <colin.king@...el.com>,
        James Clark <james.clark@....com>,
        Fangrui Song <maskray@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Zechuan Chen <chenzechuan1@...wei.com>,
        Jason Wang <wangborong@...rlc.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Remi Bernon <rbernon@...eweavers.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, llvm@...ts.linux.dev
Subject: Re: [PATCH v3 09/18] perf ui: Update use of pthread mutex

On Fri, Aug 26, 2022 at 1:40 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Fri, Aug 26, 2022 at 12:21 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
> >
> > On 26/08/22 22:00, Namhyung Kim wrote:
> > > On Fri, Aug 26, 2022 at 11:53 AM Adrian Hunter <adrian.hunter@...el.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? Maybe we should guard it with
a lock? Then we are back where we started. Having a clean init/exit
invariant would be best but such a change has the potential to be
large and out of scope here.

Thanks,
Ian

> Thanks,
> Namhyung