drm/msm: return -EFAULT instead of bytes remaining

copy_to/from_user returns the number of bytes remaining to be copied but
we want to return -EFAULT.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/msm_perf.c b/drivers/gpu/drm/msm/msm_perf.c
index 830857c..17fe4e53 100644
--- a/drivers/gpu/drm/msm/msm_perf.c
+++ b/drivers/gpu/drm/msm/msm_perf.c
@@ -132,7 +132,7 @@
 		size_t sz, loff_t *ppos)
 {
 	struct msm_perf_state *perf = file->private_data;
-	int n = 0, ret;
+	int n = 0, ret = 0;
 
 	mutex_lock(&perf->read_lock);
 
@@ -143,9 +143,10 @@
 	}
 
 	n = min((int)sz, perf->buftot - perf->bufpos);
-	ret = copy_to_user(buf, &perf->buf[perf->bufpos], n);
-	if (ret)
+	if (copy_to_user(buf, &perf->buf[perf->bufpos], n)) {
+		ret = -EFAULT;
 		goto out;
+	}
 
 	perf->bufpos += n;
 	*ppos += n;