ring-buffer: rb_per_cpu_empty() can return boolean

Makes rb_per_cpu_empty() return bool to improve readability.

No functional change.

Link: http://lkml.kernel.org/r/1443537816-5788-6-git-send-email-bywxiaobai@163.comSigned-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/ring_buffer.c

@@ -3039,7 +3039,7 @@ int ring_buffer_write(struct ring_buffer *buffer,
 }
 EXPORT_SYMBOL_GPL(ring_buffer_write);
 
-static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
+static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
 {
 	struct buffer_page *reader = cpu_buffer->reader_page;
 	struct buffer_page *head = rb_set_head_page(cpu_buffer);
@@ -3047,7 +3047,7 @@ static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
 
 	/* In case of error, head will be NULL */
 	if (unlikely(!head))
-		return 1;
+		return true;
 
 	return reader->read == rb_page_commit(reader) &&
 		(commit == reader ||