diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index db5b560..b98bed3 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2202,15 +2202,13 @@
 static int perf_event_period(struct perf_event *event, u64 __user *arg)
 {
 	struct perf_event_context *ctx = event->ctx;
-	unsigned long size;
 	int ret = 0;
 	u64 value;
 
 	if (!event->attr.sample_period)
 		return -EINVAL;
 
-	size = copy_from_user(&value, arg, sizeof(value));
-	if (size != sizeof(value))
+	if (copy_from_user(&value, arg, sizeof(value)))
 		return -EFAULT;
 
 	if (!value)