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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 tools/perf/util/thread.c | 6 +++---
 tools/perf/util/thread.h | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index f5af87f..74e79d2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -53,7 +53,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
                        goto err_thread;
 
                list_add(&comm->list, &thread->comm_list);
-               atomic_set(&thread->refcnt, 1);
+               refcount_set(&thread->refcnt, 1);
                RB_CLEAR_NODE(&thread->rb_node);
        }
 
@@ -88,13 +88,13 @@ void thread__delete(struct thread *thread)
 struct thread *thread__get(struct thread *thread)
 {
        if (thread)
-               atomic_inc(&thread->refcnt);
+               refcount_inc(&thread->refcnt);
        return thread;
 }
 
 void thread__put(struct thread *thread)
 {
-       if (thread && atomic_dec_and_test(&thread->refcnt)) {
+       if (thread && refcount_dec_and_test(&thread->refcnt)) {
                /*
                 * Remove it from the dead_threads list, as last reference
                 * is gone.
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 99263cb..e571885 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -1,7 +1,7 @@
 #ifndef __PERF_THREAD_H
 #define __PERF_THREAD_H
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <linux/rbtree.h>
 #include <linux/list.h>
 #include <unistd.h>
@@ -23,7 +23,7 @@ struct thread {
        pid_t                   tid;
        pid_t                   ppid;
        int                     cpu;
-       atomic_t                refcnt;
+       refcount_t              refcnt;
        char                    shortname[3];
        bool                    comm_set;
        int                     comm_len;
-- 
2.7.4

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