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[PATCH 16/35] perf evlist: Convert perf_map.refcnt from atomic_t to refcount_t

From Arnaldo Carvalho de Melo <acme@kernel.org>
Newsgroups linux.kernel
Subject [PATCH 16/35] perf evlist: Convert perf_map.refcnt from atomic_t to refcount_t
Date 2017-03-06 20:50 +0100
Message-ID <ti6NR-4s3-53@gated-at.bofh.it> (permalink)
References <ti6E9-4o1-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Elena Reshetova <elena.reshetova@intel.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@intel.com>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Kook <keescook@chromium.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Windsor <dwindsor@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans Liljestrand <ishkamiel@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kees Kook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: alsa-devel@alsa-project.org
Link: http://lkml.kernel.org/r/1487691303-31858-8-git-send-email-elena.reshetova@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/evlist.c | 18 +++++++++---------
 tools/perf/util/evlist.h |  4 ++--
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index b601f2814a30..564b924fb48a 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -777,7 +777,7 @@ union perf_event *perf_mmap__read_forward(struct perf_mmap *md, bool check_messu
 	/*
 	 * Check if event was unmapped due to a POLLHUP/POLLERR.
 	 */
-	if (!atomic_read(&md->refcnt))
+	if (!refcount_read(&md->refcnt))
 		return NULL;
 
 	head = perf_mmap__read_head(md);
@@ -794,7 +794,7 @@ perf_mmap__read_backward(struct perf_mmap *md)
 	/*
 	 * Check if event was unmapped due to a POLLHUP/POLLERR.
 	 */
-	if (!atomic_read(&md->refcnt))
+	if (!refcount_read(&md->refcnt))
 		return NULL;
 
 	head = perf_mmap__read_head(md);
@@ -856,7 +856,7 @@ void perf_mmap__read_catchup(struct perf_mmap *md)
 {
 	u64 head;
 
-	if (!atomic_read(&md->refcnt))
+	if (!refcount_read(&md->refcnt))
 		return;
 
 	head = perf_mmap__read_head(md);
@@ -875,14 +875,14 @@ static bool perf_mmap__empty(struct perf_mmap *md)
 
 static void perf_mmap__get(struct perf_mmap *map)
 {
-	atomic_inc(&map->refcnt);
+	refcount_inc(&map->refcnt);
 }
 
 static void perf_mmap__put(struct perf_mmap *md)
 {
-	BUG_ON(md->base && atomic_read(&md->refcnt) == 0);
+	BUG_ON(md->base && refcount_read(&md->refcnt) == 0);
 
-	if (atomic_dec_and_test(&md->refcnt))
+	if (refcount_dec_and_test(&md->refcnt))
 		perf_mmap__munmap(md);
 }
 
@@ -894,7 +894,7 @@ void perf_mmap__consume(struct perf_mmap *md, bool overwrite)
 		perf_mmap__write_tail(md, old);
 	}
 
-	if (atomic_read(&md->refcnt) == 1 && perf_mmap__empty(md))
+	if (refcount_read(&md->refcnt) == 1 && perf_mmap__empty(md))
 		perf_mmap__put(md);
 }
 
@@ -937,7 +937,7 @@ static void perf_mmap__munmap(struct perf_mmap *map)
 		munmap(map->base, perf_mmap__mmap_len(map));
 		map->base = NULL;
 		map->fd = -1;
-		atomic_set(&map->refcnt, 0);
+		refcount_set(&map->refcnt, 0);
 	}
 	auxtrace_mmap__munmap(&map->auxtrace_mmap);
 }
@@ -1001,7 +1001,7 @@ static int perf_mmap__mmap(struct perf_mmap *map,
 	 * evlist layer can't just drop it when filtering events in
 	 * perf_evlist__filter_pollfd().
 	 */
-	atomic_set(&map->refcnt, 2);
+	refcount_set(&map->refcnt, 2);
 	map->prev = 0;
 	map->mask = mp->mask;
 	map->base = mmap(NULL, perf_mmap__mmap_len(map), mp->prot,
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 389b9ccdf8c7..39942995f537 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -1,7 +1,7 @@
 #ifndef __PERF_EVLIST_H
 #define __PERF_EVLIST_H 1
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <linux/list.h>
 #include <api/fd/array.h>
 #include <stdio.h>
@@ -29,7 +29,7 @@ struct perf_mmap {
 	void		 *base;
 	int		 mask;
 	int		 fd;
-	atomic_t	 refcnt;
+	refcount_t	 refcnt;
 	u64		 prev;
 	struct auxtrace_mmap auxtrace_mmap;
 	char		 event_copy[PERF_SAMPLE_MAX_SIZE] __attribute__((aligned(8)));
-- 
2.9.3

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[GIT PULL 00/35] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 22/35] perf cpumap: Introduce cpu_map__snprint_mask() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 12/35] perf comm: Convert comm_str.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 30/35] perf tools: Force uncore events to system wide monitoring Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 27/35] perf probe: Generalize probe event file open routine Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 17/35] perf thread: convert thread.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 25/35] kretprobes: Ensure probe location is at function entry Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 13/35] perf dso: Convert dso.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 21/35] perf ftrace: Add support for --pid option Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 19/35] perf evlist: Clarify a bit the use of perf_mmap->refcnt Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 23/35] perf ftrace: Add support for -a and -C option Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 10/35] perf cgroup: Convert cgroup_sel.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 07/35] tools include: Provide gcc based cmpxchg fallback for !x86 Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 20/35] perf tools: Allow sorting by symbol size Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 28/35] perf intel-PT/BTS: Add missing initialization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 33/35] perf bench futex: Fix build on musl + clang Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 05/35] tools arch x86: Introduce atomic_cmpxchg() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 14/35] perf map: Convert map.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 16/35] perf evlist: Convert perf_map.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 06/35] tools include: Introduce atomic_cmpxchg_{relaxed,release}() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 24/35] perf ftrace: Use pager for displaying result Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 35/35] perf bench numa: Add more comment for -c option Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 11/35] perf cpumap: Convert cpu_map.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 02/35] perf stat: Issue a HW watchdog disable hint Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 26/35] trace/kprobes: Allow return probes with offsets and absolute addresses Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 15/35] perf map: Convert map_groups.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 01/35] perf vendor events: Add mapping for KnightsMill PMU events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 32/35] perf bench futex: Use __maybe_unused Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 29/35] trace/kprobes: Add back warning about offset in return probes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 31/35] tools build: Add test for sched_getcpu() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 09/35] tools include: Adopt kernel's refcount.h Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 18/35] perf thread_map: Convert thread_map.refcnt from atomic_t to refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  [PATCH 34/35] tools build: Use the same CC for feature detection and actual build Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-03-06 20:50 +0100
  Re: [GIT PULL 00/35] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-03-07 08:20 +0100

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