Emil Goode <emilgoode@xxxxxxxxx> writes: > On Thu, Feb 06, 2014 at 03:28:13PM +0000, David Laight wrote: >> From: Igor Gnatenko >> > On Thu, 2014-02-06 at 13:56 +0100, Emil Goode wrote: >> > > The AX88772B occasionally send rx packets that cross urb boundaries >> > > and the remaining partial packet is sent with no header. >> > > When the buffer with a partial packet is of less number of octets >> > > than the value of hard_header_len the buffer is discarded by the >> > > usbnet module. This is causing dropped packages and error messages >> > > in dmesg. > I will do some more digging in the code, but the test of skb->len > against hard_header_len is done already in the completion callback > function passed to usb_fill_bulk_urb so it seems that buffers of less > than hard_header_len number of octets will be dropped regardless. I am pretty sure you are right about this bug. And the exact same solution is already used by the cx82310_eth minidriver, so I don't see the problem. Your fix is fine IMHO. But you should apply it to all the devices using asix_rx_fixup_common(), not just the ax88772 ones. You could maybe make this a usbnet flag instead and create a generic solution in usbnet, but frankly I believe the number of flags and their meaning have exceeded drivers authors capabilities a long time ago. At least mine, which are quite limited ;-) An example of that problem is another bloody obvious bug I noticed while looking at this driver: The 'struct driver_info ax88178_info' points to asix_rx_fixup_common without setting the FLAG_MULTI_PACKET. This will result in usbnet rx_process() calling usbnet_skb_return() on skbs which are already consumed by the minidriver. Not a big problem, but will give some odd results. But if you allow skbs shorter than ETH_HLEN to slip through then it might go boom, so you should probably fix that as well. Bjørn -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
