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

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Date:   Wed, 12 Apr 2023 14:45:01 -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:
> > This change is intended to catch:
> >  - use after put: using a cpumap after you have put it will cause a
> >    segv.
> >  - unbalanced puts: two puts for a get will result in a double free
> >    that can be captured and reported by tools like address sanitizer,
> >    including with the associated stack traces of allocation and frees.
> >  - missing puts: if a put is missing then the get turns into a memory
> >    leak that can be reported by leak sanitizer, including the stack
> >    trace at the point the get occurs.
 
> I think this should be further split into self contained patches as it
> does:
> 
> 2. Exports perf_cpu_map__alloc() from libperf for use in tools/perf
> 
> And its usage should be on a separate patch:
> 
> > -     struct perf_cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(int) * nr);
> > +     struct perf_cpu_map *cpus = perf_cpu_map__alloc(nr);

>From 1f94479edb4decdcec3e902528abb47f0ccd5d16 Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@...gle.com>
Date: Wed, 12 Apr 2023 12:54:44 -0300
Subject: [PATCH 1/1] libperf: Make perf_cpu_map__alloc() available as an
 internal function for tools/perf to use

We had the open coded equivalent in perf_cpu_map__empty_new(), so reuse
what is in libperf.

Signed-off-by: Ian Rogers <irogers@...gle.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@...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/lkml/20230407230405.2931830-3-irogers@google.com
[ Split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/lib/perf/cpumap.c                  | 2 +-
 tools/lib/perf/include/internal/cpumap.h | 1 +
 tools/perf/util/cpumap.c                 | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index 6cd0be7c1bb438e5..0833423c243b9b49 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -10,7 +10,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-static struct perf_cpu_map *perf_cpu_map__alloc(int 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 35dd29642296e660..f5bffb1f86748ca2 100644
--- a/tools/lib/perf/include/internal/cpumap.h
+++ b/tools/lib/perf/include/internal/cpumap.h
@@ -24,6 +24,7 @@ struct perf_cpu_map {
 #define MAX_NR_CPUS	2048
 #endif
 
+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);
 
diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index c8484b75413ef709..072831f0cad46065 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -160,7 +160,7 @@ size_t cpu_map__fprintf(struct perf_cpu_map *map, FILE *fp)
 
 struct perf_cpu_map *perf_cpu_map__empty_new(int nr)
 {
-	struct perf_cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(int) * nr);
+	struct perf_cpu_map *cpus = perf_cpu_map__alloc(nr);
 
 	if (cpus != NULL) {
 		int i;
-- 
2.39.2