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From: Namhyung Kim <namhyung@kernel.org>
Date: Fri, 22 Mar 2024 13:54:06 -0700
Message-ID: <CAM9d7chjyg9TyPLO68Tx3dWO1itT8bfMCuu4ATV_hV-47MjZUA@mail.gmail.com>
Subject: Re: [PATCH v2 04/13] perf dsos: Add dsos__for_each_dso
To: Ian Rogers <irogers@google.com>
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>, Jiri Olsa <jolsa@kernel.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, James Clark <james.clark@arm.com>, 
	Athira Rajeev <atrajeev@linux.vnet.ibm.com>, Colin Ian King <colin.i.king@gmail.com>, 
	=?UTF-8?Q?Ahelenia_Ziemia=C5=84ska?= <nabijaczleweli@nabijaczleweli.xyz>, 
	Leo Yan <leo.yan@linux.dev>, Song Liu <song@kernel.org>, Miguel Ojeda <ojeda@kernel.org>, 
	Liam Howlett <liam.howlett@oracle.com>, Ilkka Koskinen <ilkka@os.amperecomputing.com>, 
	Ben Gainey <ben.gainey@arm.com>, K Prateek Nayak <kprateek.nayak@amd.com>, 
	Kan Liang <kan.liang@linux.intel.com>, Yanteng Si <siyanteng@loongson.cn>, 
	Ravi Bangoria <ravi.bangoria@amd.com>, Sun Haiyong <sunhaiyong@loongson.cn>, 
	Changbin Du <changbin.du@huawei.com>, Masami Hiramatsu <mhiramat@kernel.org>, 
	zhaimingbing <zhaimingbing@cmss.chinamobile.com>, Paran Lee <p4ranlee@gmail.com>, 
	Li Dong <lidong@vivo.com>, elfring@users.sourceforge.net, 
	Andi Kleen <ak@linux.intel.com>, Markus Elfring <Markus.Elfring@web.de>, 
	Chengen Du <chengen.du@canonical.com>, linux-perf-users@vger.kernel.org, 
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org
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On Fri, Mar 22, 2024 at 1:43=E2=80=AFPM Namhyung Kim <namhyung@kernel.org> =
wrote:
>
> Hi Ian,
>
> On Thu, Mar 21, 2024 at 9:03=E2=80=AFAM Ian Rogers <irogers@google.com> w=
rote:
> >
> > To better abstract the dsos internals, add dsos__for_each_dso that
> > does a callback on each dso. This also means the read lock can be
> > correctly held.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
[SNIP]
> > diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
> > index d269e09005a7..d43f64939b12 100644
> > --- a/tools/perf/util/dsos.c
> > +++ b/tools/perf/util/dsos.c
> > @@ -433,3 +433,19 @@ struct dso *dsos__find_kernel_dso(struct dsos *dso=
s)
> >         up_read(&dsos->lock);
> >         return res;
> >  }
> > +
> > +int dsos__for_each_dso(struct dsos *dsos, int (*cb)(struct dso *dso, v=
oid *data), void *data)
> > +{
> > +       struct dso *dso;
> > +
> > +       down_read(&dsos->lock);
> > +       list_for_each_entry(dso, &dsos->head, node) {
> > +               int err;
> > +
> > +               err =3D cb(dso, data);
> > +               if (err)
> > +                       return err;
>
> Please break and return the error to release the lock.

Hmm.. I saw this code was replaced by the next patch.
Then probably it'd be ok to leave it.

Thanks,
Namhyung

>
> > +       }
> > +       up_read(&dsos->lock);
> > +       return 0;
> > +}