ftrace: Use guard to take the ftrace_lock in release_probe()

The ftrace_lock is held throughout the entire release_probe() function.
Use guard to simplify any exit paths.

Cc: Masami Hiramatsu <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: rostedt

kernel/trace/ftrace.c

@@ -5288,7 +5288,7 @@ static void release_probe(struct ftrace_func_probe *probe)
 {
 	struct ftrace_probe_ops *probe_ops;
 
-	mutex_lock(&ftrace_lock);
+	guard(mutex)(&ftrace_lock);
 
 	WARN_ON(probe->ref <= 0);
 
@@ -5306,7 +5306,6 @@ static void release_probe(struct ftrace_func_probe *probe)
 		list_del(&probe->list);
 		kfree(probe);
 	}
-	mutex_unlock(&ftrace_lock);
 }
 
 static void acquire_probe_locked(struct ftrace_func_probe *probe)