From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jakob Unterwurzacher Subject: Re: [bug, bisected] pfifo_fast causes packet reordering Date: Thu, 15 Mar 2018 19:08:45 +0100 Message-ID: <3a959e50-8656-5d9c-97b9-227d733948f8@theobroma-systems.com> References: <946dbe16-a2eb-eca8-8069-468859ccc78d@theobroma-systems.com> <95844480-d020-9000-53ef-0da8b965ce6e@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <95844480-d020-9000-53ef-0da8b965ce6e@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: John Fastabend , Dave Taht Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , "linux-can@vger.kernel.org" , Martin Elshuber List-Id: linux-can.vger.kernel.org On 14.03.18 05:03, John Fastabend wrote: > On 03/13/2018 11:35 AM, Dave Taht wrote: >> On Tue, Mar 13, 2018 at 11:24 AM, Jakob Unterwurzacher >> wrote: >>> During stress-testing our "ucan" USB/CAN adapter SocketCAN driver on Linux >>> v4.16-rc4-383-ged58d66f60b3 we observed that a small fraction of packets are >>> delivered out-of-order. >>> > > Is the stress-testing tool available somewhere? What type of packets > are being sent? I have reproduced it using two USB network cards connected to each other. The test tool sends UDP packets containing a counter and listens on the other interface, it is available at https://github.com/jakob-tsd/pfifo_stress/blob/master/pfifo_stress.py Here is what I get: root@rk3399-q7:~# ./pfifo_stress.py [...] expected ctr 0xcdc, received 0xcdd expected ctr 0xcde, received 0xcdc expected ctr 0xcdd, received 0xcde expected ctr 0xe3c, received 0xe3d expected ctr 0xe3e, received 0xe3c expected ctr 0xe3d, received 0xe3e expected ctr 0x1097, received 0x1098 expected ctr 0x1099, received 0x1097 expected ctr 0x1098, received 0x1099 expected ctr 0x17c0, received 0x17c1 expected ctr 0x17c2, received 0x17c0 [...] Best regards, Jakob