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Groups > linux.kernel > #1593640

[PATCH 12/35] perf comm: Convert comm_str.refcnt from atomic_t to refcount_t

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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/1487691303-31858-4-git-send-email-elena.reshetova@intel.com
[ Reinstated comm_str__get() function, needed when reusing entries in the rbtree ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/comm.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c
index 21b7ff382c3f..32837b6f7879 100644
--- a/tools/perf/util/comm.c
+++ b/tools/perf/util/comm.c
@@ -2,12 +2,12 @@
 #include "util.h"
 #include <stdlib.h>
 #include <stdio.h>
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 
 struct comm_str {
 	char *str;
 	struct rb_node rb_node;
-	atomic_t refcnt;
+	refcount_t refcnt;
 };
 
 /* Should perhaps be moved to struct machine */
@@ -16,13 +16,13 @@ static struct rb_root comm_str_root;
 static struct comm_str *comm_str__get(struct comm_str *cs)
 {
 	if (cs)
-		atomic_inc(&cs->refcnt);
+		refcount_inc(&cs->refcnt);
 	return cs;
 }
 
 static void comm_str__put(struct comm_str *cs)
 {
-	if (cs && atomic_dec_and_test(&cs->refcnt)) {
+	if (cs && refcount_dec_and_test(&cs->refcnt)) {
 		rb_erase(&cs->rb_node, &comm_str_root);
 		zfree(&cs->str);
 		free(cs);
@@ -43,7 +43,7 @@ static struct comm_str *comm_str__alloc(const char *str)
 		return NULL;
 	}
 
-	atomic_set(&cs->refcnt, 0);
+	refcount_set(&cs->refcnt, 1);
 
 	return cs;
 }
@@ -61,7 +61,7 @@ static struct comm_str *comm_str__findnew(const char *str, struct rb_root *root)
 
 		cmp = strcmp(str, iter->str);
 		if (!cmp)
-			return iter;
+			return comm_str__get(iter);
 
 		if (cmp < 0)
 			p = &(*p)->rb_left;
@@ -95,8 +95,6 @@ struct comm *comm__new(const char *str, u64 timestamp, bool exec)
 		return NULL;
 	}
 
-	comm_str__get(comm->comm_str);
-
 	return comm;
 }
 
@@ -108,7 +106,6 @@ int comm__override(struct comm *comm, const char *str, u64 timestamp, bool exec)
 	if (!new)
 		return -ENOMEM;
 
-	comm_str__get(new);
 	comm_str__put(old);
 	comm->comm_str = new;
 	comm->start = timestamp;
-- 
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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