[for-linus][PATCH 2/9] tracing: Use refcount for trace_event_file reference counter

[Steven Rostedt <rostedt@goodmis.org>]

From: Steven Rostedt <rostedt@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').

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20240726144208.687cce24@rorschach.local.home
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@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 f08fbaf8cad6..7266ec2a4eea 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;
@@ -3003,7 +3003,7 @@ 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