copy_to_user() returns number of not copied bytes, not error code.

Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
---
 drivers/usb/misc/adutux.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
index d240de0..801324a 100644
--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -439,7 +439,7 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
 			/* drain secondary buffer */
 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
-			if (i < 0) {
+			if (i) {
 				retval = -EFAULT;
 				goto exit;
 			}
-- 
1.7.0.4