Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2;
Date:   Mon, 27 Nov 2023 18:53:19 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Ian Rogers <irogers@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Nick Terrell <terrelln@fb.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        Huacai Chen <chenhuacai@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        "Steinar H. Gunderson" <sesse@google.com>,
        Liam Howlett <liam.howlett@oracle.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Colin Ian King <colin.i.king@gmail.com>,
        Dmitrii Dolgov <9erthalion6@gmail.com>,
        Yang Jihong <yangjihong1@huawei.com>,
        Ming Wang <wangming01@loongson.cn>,
        James Clark <james.clark@arm.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Leo Yan <leo.yan@linaro.org>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        German Gomez <german.gomez@arm.com>,
        Changbin Du <changbin.du@huawei.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Li Dong <lidong@vivo.com>,
        Sandipan Das <sandipan.das@amd.com>,
        liuwenyu <liuwenyu7@huawei.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v4 01/53] perf comm: Use regular mutex
Message-ID: <ZWUPz6ETFEBsrDkZ@kernel.org>
References: <20231102175735.2272696-1-irogers@google.com>
 <20231102175735.2272696-2-irogers@google.com>
 <CAM9d7cgbPGzgc=QG8dStvq1iX8snGyeKTJDrg2XBjX0pCX9Qtg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CAM9d7cgbPGzgc=QG8dStvq1iX8snGyeKTJDrg2XBjX0pCX9Qtg@mail.gmail.com>
Precedence: bulk

Em Sun, Nov 05, 2023 at 09:31:47AM -0800, Namhyung Kim escreveu:
> Hi Ian,
> 
> On Thu, Nov 2, 2023 at 10:58 AM Ian Rogers <irogers@google.com> wrote:
> >
> > The rwsem is only after used for writing so switch to a mutex that has
> > better error checking.
> 
> Hmm.. ok.  It doesn't make sense to use rwsem without readers.

Well, the only reader is a findnew method, that will primarily read,
but possibly write if it doesn't find it there, so converting to a
regular mutex seems sensible.

- Arnaldo
 
> > Fixes: 7a8f349e9d14 ("perf rwsem: Add debug mode that uses a mutex")
> 
> But I'm not sure this is a fix.  Other than that,

Yeah, agreed, will remove the fixes.
 
> > Signed-off-by: Ian Rogers <irogers@google.com>
> 
> Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,

- Arnaldo