No behaviour change.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/char/mem.c

@@ -131,6 +131,7 @@ static ssize_t read_mem(struct file * file, char __user * buf,
 			size_t count, loff_t *ppos)
 {
 	unsigned long p = *ppos;
+	unsigned long ret;
 	ssize_t read, sz;
 	char *ptr;
 
@@ -169,12 +170,10 @@ static ssize_t read_mem(struct file * file, char __user * buf,
 		if (!ptr)
 			return -EFAULT;
 
-		if (copy_to_user(buf, ptr, sz)) {
-			unxlate_dev_mem_ptr(p, ptr);
-			return -EFAULT;
-		}
-
+		ret = copy_to_user(buf, ptr, sz);
 		unxlate_dev_mem_ptr(p, ptr);
+		if (ret)
+			return -EFAULT;
 
 		buf += sz;
 		p += sz;
@@ -232,16 +231,14 @@ static ssize_t write_mem(struct file * file, const char __user * buf,
 		}
 
 		copied = copy_from_user(ptr, buf, sz);
+		unxlate_dev_mem_ptr(p, ptr);
 		if (copied) {
 			written += sz - copied;
-			unxlate_dev_mem_ptr(p, ptr);
 			if (written)
 				break;
 			return -EFAULT;
 		}
 
-		unxlate_dev_mem_ptr(p, ptr);
-
 		buf += sz;
 		p += sz;
 		count -= sz;