linux-kernel - Re: [PATCH v7 2/5] perf cpumap: Add reference count checking

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Message-ID: <ZDbwx8dbIdQNEtMF@kernel.org>
Date:   Wed, 12 Apr 2023 14:56:23 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        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>,
        James Clark <james.clark@....com>,
        John Garry <john.g.garry@...cle.com>,
        Riccardo Mancini <rickyman7@...il.com>,
        Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Leo Yan <leo.yan@...aro.org>, Andi Kleen <ak@...ux.intel.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Shunsuke Nakamura <nakamura.shun@...itsu.com>,
        Song Liu <song@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Miaoqian Lin <linmq006@...il.com>,
        Stephen Brennan <stephen.s.brennan@...cle.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        German Gomez <german.gomez@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Hao Luo <haoluo@...gle.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v7 2/5] perf cpumap: Add reference count checking

Em Tue, Apr 11, 2023 at 03:19:06PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Apr 07, 2023 at 04:04:02PM -0700, Ian Rogers escreveu:
> I think this should be further split into self contained patches as it
> does:
> These should be in a separate patchset using a new perf_cpu_map__set_nr() macro:
> 
> > +     RC_CHK_ACCESS(unmatched_cpus)->nr = unmatched_nr;
> > +     RC_CHK_ACCESS(matched_cpus)->nr = matched_nr;

One more, next one will be this:

⬢[acme@...lbox perf-tools-next]$ git diff
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 561e2616861f8bd9..760c848c9fa27728 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -2020,8 +2020,8 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
                        matched_cpus->map[matched_nr++] = cpu;
        }

-       unmatched_cpus->nr = unmatched_nr;
-       matched_cpus->nr = matched_nr;
+       perf_cpu_map__set_nr(unmatched_cpus, unmatched_nr);
+       perf_cpu_map__set_nr(matched_cpus, matched_nr);
        *mcpus_ptr = matched_cpus;
        *ucpus_ptr = unmatched_cpus;
        return 0;
⬢[acme@...lbox perf-tools-next]$

>From b277851417e0149aff5e6986e1ad6e2d8054e4a6 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@...hat.com>
Date: Wed, 12 Apr 2023 14:53:35 -0300
Subject: [PATCH 1/1] libperf: Add a perf_cpu_map__set_nr() available as an
 internal function for tools/perf to use

We'll need to reference count check 'struct perf_cpu_map', so wrap
accesses to its internal state to allow intercepting accesses to its
instances.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@...gle.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Riccardo Mancini <rickyman7@...il.com>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Stephen Brennan <stephen.s.brennan@...cle.com>
Link: https://lore.kernel.org/
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/lib/perf/cpumap.c                  | 5 +++++
 tools/lib/perf/include/internal/cpumap.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 0833423c243b9b49..6bbcbb83eb14cc45 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -10,6 +10,11 @@
 #include <ctype.h>
 #include <limits.h>
 
+void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus)
+{
+	map->nr = nr_cpus;
+}
+
 struct perf_cpu_map *perf_cpu_map__alloc(int nr_cpus)
 {
 	struct perf_cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(struct perf_cpu) * nr_cpus);
diff --git a/tools/lib/perf/include/internal/cpumap.h b/tools/lib/perf/include/internal/cpumap.h
index f5bffb1f86748ca2..b82fd6607a00e3dc 100644
--- a/tools/lib/perf/include/internal/cpumap.h
+++ b/tools/lib/perf/include/internal/cpumap.h
@@ -28,4 +28,6 @@ struct perf_cpu_map *perf_cpu_map__alloc(int nr_cpus);
 int perf_cpu_map__idx(const struct perf_cpu_map *cpus, struct perf_cpu cpu);
 bool perf_cpu_map__is_subset(const struct perf_cpu_map *a, const struct perf_cpu_map *b);
 
+void perf_cpu_map__set_nr(struct perf_cpu_map *map, int nr_cpus);
+
 #endif /* __LIBPERF_INTERNAL_CPUMAP_H */
-- 
2.39.2