linux-kernel - [PATCH 10/35] perf cgroup: Convert cgroup_sel.refcnt from atomic_t to refcount

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Message-Id: <20170306193825.24011-11-acme@kernel.org>
Date:   Mon,  6 Mar 2017 16:38:00 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Elena Reshetova <elena.reshetova@...el.com>,
        David Windsor <dwindsor@...il.com>,
        Hans Liljestrand <ishkamiel@...il.com>,
        Kees Kook <keescook@...omium.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        alsa-devel@...a-project.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@...ia.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 10/35] perf cgroup: Convert cgroup_sel.refcnt from atomic_t to refcount_t

From: Elena Reshetova <elena.reshetova@...el.com>

The refcount_t type and corresponding API should be used instead of
atomic_t when the variable is used as a reference counter.

This allows to avoid accidental refcounter overflows that might lead to
use-after-free situations.

Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
Signed-off-by: David Windsor <dwindsor@...il.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Kook <keescook@...omium.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: alsa-devel@...a-project.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Windsor <dwindsor@...il.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Hans Liljestrand <ishkamiel@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kees Kook <keescook@...omium.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@...ia.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/1487691303-31858-2-git-send-email-elena.reshetova@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/cgroup.c | 6 +++---
 tools/perf/util/cgroup.h | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index eafbf11442b2..86399eda3684 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -127,19 +127,19 @@ static int add_cgroup(struct perf_evlist *evlist, char *str)
 			goto found;
 		n++;
 	}
-	if (atomic_read(&cgrp->refcnt) == 0)
+	if (refcount_read(&cgrp->refcnt) == 0)
 		free(cgrp);
 
 	return -1;
 found:
-	atomic_inc(&cgrp->refcnt);
+	refcount_inc(&cgrp->refcnt);
 	counter->cgrp = cgrp;
 	return 0;
 }
 
 void close_cgroup(struct cgroup_sel *cgrp)
 {
-	if (cgrp && atomic_dec_and_test(&cgrp->refcnt)) {
+	if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) {
 		close(cgrp->fd);
 		zfree(&cgrp->name);
 		free(cgrp);
diff --git a/tools/perf/util/cgroup.h b/tools/perf/util/cgroup.h
index 31f8dcdbd7ef..d91966b97cbd 100644
--- a/tools/perf/util/cgroup.h
+++ b/tools/perf/util/cgroup.h
@@ -1,14 +1,14 @@
 #ifndef __CGROUP_H__
 #define __CGROUP_H__
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 
 struct option;
 
 struct cgroup_sel {
 	char *name;
 	int fd;
-	atomic_t refcnt;
+	refcount_t refcnt;
 };
 
 
-- 
2.9.3