[PERF EVENTS] fix incorrect copy_from_user usage

[Joe Korty]

perf events: repair incorrect use of copy_from_user

This makes the perf_event_period() return 0 instead of
-EFAULT on success.

Developed-by: John Blackwood <john.blackwood@xxxxxxxx>
Signed-off-by: Joe Korty <joe.korty@xxxxxxxx>

Index: 2.6.36-rc5/kernel/perf_event.c
===================================================================
--- 2.6.36-rc5.orig/kernel/perf_event.c	2010-09-28 17:38:16.000000000 -0400
+++ 2.6.36-rc5/kernel/perf_event.c	2010-09-28 17:48:10.000000000 -0400
@@ -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)
--
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