ftrace: Use guard for match_records()

The ftrace_lock is held for most of match_records() until the end of the
function. Use guard to make error paths simpler.

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

@@ -4829,15 +4829,13 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
 		mod_g.len = strlen(mod_g.search);
 	}
 
-	mutex_lock(&ftrace_lock);
+	guard(mutex)(&ftrace_lock);
 
 	if (unlikely(ftrace_disabled))
-		goto out_unlock;
+		return 0;
 
-	if (func_g.type == MATCH_INDEX) {
-		found = add_rec_by_index(hash, &func_g, clear_filter);
-		goto out_unlock;
-	}
+	if (func_g.type == MATCH_INDEX)
+		return add_rec_by_index(hash, &func_g, clear_filter);
 
 	do_for_each_ftrace_rec(pg, rec) {
 
@@ -4846,16 +4844,12 @@ match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
 
 		if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
 			ret = enter_record(hash, rec, clear_filter);
-			if (ret < 0) {
-				found = ret;
-				goto out_unlock;
-			}
+			if (ret < 0)
+				return ret;
 			found = 1;
 		}
 		cond_resched();
 	} while_for_each_ftrace_rec();
- out_unlock:
-	mutex_unlock(&ftrace_lock);
 
 	return found;
 }