Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755307AbaBFPAs (ORCPT ); Thu, 6 Feb 2014 10:00:48 -0500 Received: from mail-lb0-f174.google.com ([209.85.217.174]:56229 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752750AbaBFPAo (ORCPT ); Thu, 6 Feb 2014 10:00:44 -0500 Date: Thu, 6 Feb 2014 16:02:26 +0100 From: Emil Goode To: David Laight Cc: "David S. Miller" , Ming Lei , Mark Brown , Jeff Kirsher , Glen Turner , "linux-usb@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] net: asix: fix bad header length bug Message-ID: <20140206150226.GA5251@lianli> References: <1391691384-8486-1-git-send-email-emilgoode@gmail.com> <063D6719AE5E284EB5DD2968C1650D6D0F6B98CA@AcuExch.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F6B98CA@AcuExch.aculab.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello David, Thank's for the review. On Thu, Feb 06, 2014 at 01:37:12PM +0000, David Laight wrote: > From: Emil Goode > > 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. > > > > This can be reproduced by using ping with a packet size > > between 1965-1976. > > I think this can affect other USB ethernet drivers. > Probably most of the ones that explicitly set rx_urb_len. > > The ax88179_178a driver sets massive 20k receive urb. The ax88179_178a has it's own bind function, so I believe it's not affected by this change. > I've seen over 10k of data in a single urb, dunno if it > can actually generate more than 20k - possibly if the usb3 link > is loaded with other traffic. > It would be much more efficient for it to use an aligned 4k urb > and then merge the fragment into skbs. > > Once you've set: > + dev->net->hard_header_len = 0; /* Partial packets have no header */ > try setting the mtu to a multiple of 1k. I tried setting the mtu to 2000 and when using ping with a large enough packet size to fill the urb to rx_urb_size all packages are dropped. > There is a very odd check in usbnet_change_mtu() that tries to stop the > receive urb_length being a multiple of the usb packet size. This is very odd indeed! > > This code looks as though it is hoping that the usb controller will discard > any full length bulk messages after finding a short buffer. > I suspect that might be just wishful thinking! > > David > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/