[PATCH] tracing: Use refcount for trace_event_file reference counter

[Steven Rostedt]

From: Steven Rostedt <rost...@goodmis.org>

Instead of using an atomic counter for the trace_event_file reference
counter, use the refcount interface. It has various checks to make sure
the reference counting is correct, and will warn if it detects an error
(like refcount_inc() on '0').

Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 include/linux/trace_events.h | 2 +-
 kernel/trace/trace_events.c  | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 9df3e2973626..fed58e54f15e 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -680,7 +680,7 @@ struct trace_event_file {
         * caching and such. Which is mostly OK ;-)
         */
        unsigned long           flags;
-       atomic_t                ref;    /* ref count for opened files */
+       refcount_t              ref;    /* ref count for opened files */
        atomic_t                sm_ref; /* soft-mode reference counter */
        atomic_t                tm_ref; /* trigger-mode reference counter */
 };
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 852643d957de..81ade9ddcbe5 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -992,18 +992,18 @@ static void remove_subsystem(struct trace_subsystem_dir 
*dir)
 
 void event_file_get(struct trace_event_file *file)
 {
-       atomic_inc(&file->ref);
+       refcount_inc(&file->ref);
 }
 
 void event_file_put(struct trace_event_file *file)
 {
-       if (WARN_ON_ONCE(!atomic_read(&file->ref))) {
+       if (WARN_ON_ONCE(!refcount_read(&file->ref))) {
                if (file->flags & EVENT_FILE_FL_FREED)
                        kmem_cache_free(file_cachep, file);
                return;
        }
 
-       if (atomic_dec_and_test(&file->ref)) {
+       if (refcount_dec_and_test(&file->ref)) {
                /* Count should only go to zero when it is freed */
                if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED)))
                        return;
@@ -2999,7 +2999,7 @@ trace_create_new_event(struct trace_event_call *call,
        atomic_set(&file->tm_ref, 0);
        INIT_LIST_HEAD(&file->triggers);
        list_add(&file->list, &tr->events);
-       event_file_get(file);
+       refcount_set(&file->ref, 1);
 
        return file;
 }
-- 
2.43.0