tracing/eprobe: Adopt guard() and scoped_guard()

Use guard() or scoped_guard() in eprobe events for critical sections
rather than discrete lock/unlock pairs.

Link: https://lore.kernel.org/all/173289890996.73724.17421347964110362029.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Author: mhiramat

kernel/trace/trace_eprobe.c

@@ -917,10 +917,10 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 		goto error;
 	}
 
-	mutex_lock(&event_mutex);
-	event_call = find_and_get_event(sys_name, sys_event);
-	ep = alloc_event_probe(group, event, event_call, argc - 2);
-	mutex_unlock(&event_mutex);
+	scoped_guard(mutex, &event_mutex) {
+		event_call = find_and_get_event(sys_name, sys_event);
+		ep = alloc_event_probe(group, event, event_call, argc - 2);
+	}
 
 	if (IS_ERR(ep)) {
 		ret = PTR_ERR(ep);
@@ -952,23 +952,21 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	if (ret < 0)
 		goto error;
 	init_trace_eprobe_call(ep);
-	mutex_lock(&event_mutex);
-	ret = trace_probe_register_event_call(&ep->tp);
-	if (ret) {
-		if (ret == -EEXIST) {
-			trace_probe_log_set_index(0);
-			trace_probe_log_err(0, EVENT_EXIST);
+	scoped_guard(mutex, &event_mutex) {
+		ret = trace_probe_register_event_call(&ep->tp);
+		if (ret) {
+			if (ret == -EEXIST) {
+				trace_probe_log_set_index(0);
+				trace_probe_log_err(0, EVENT_EXIST);
+			}
+			goto error;
+		}
+		ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
+		if (ret < 0) {
+			trace_probe_unregister_event_call(&ep->tp);
+			goto error;
 		}
-		mutex_unlock(&event_mutex);
-		goto error;
-	}
-	ret = dyn_event_add(&ep->devent, &ep->tp.event->call);
-	if (ret < 0) {
-		trace_probe_unregister_event_call(&ep->tp);
-		mutex_unlock(&event_mutex);
-		goto error;
 	}
-	mutex_unlock(&event_mutex);
 	return ret;
 parse_error:
 	ret = -EINVAL;