perf: Fix incorrect copy_from_user() usage

perf events: repair incorrect use of copy_from_user

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

Signed-off-by: John Blackwood<john.blackwood@ccur.com>
Signed-off-by: Joe Korty <joe.korty@ccur.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100928220311.GA18145@tsunami.ccur.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 3 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index db5b56064687..b98bed3d8182 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2202,15 +2202,13 @@ static void perf_event_for_each(struct perf_event *event,
 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)