From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758513AbdLRTx2 (ORCPT ); Mon, 18 Dec 2017 14:53:28 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:40172 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753028AbdLRTxY (ORCPT ); Mon, 18 Dec 2017 14:53:24 -0500 Date: Mon, 18 Dec 2017 14:53:22 -0500 (EST) Message-Id: <20171218.145322.67839475851416152.davem@davemloft.net> To: al.kochet@gmail.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, f.fainelli@gmail.com, edumazet@google.com Subject: Re: [PATCH] net: arc_emac: restart stalled EMAC From: David Miller In-Reply-To: <1513336371-21325-1-git-send-email-al.kochet@gmail.com> References: <1513336371-21325-1-git-send-email-al.kochet@gmail.com> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Mon, 18 Dec 2017 11:53:24 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Kochetkov Date: Fri, 15 Dec 2017 14:12:51 +0300 > Under certain conditions EMAC stop reception of incoming packets and > continuously increment R_MISS register instead of saving data into > provided buffer. The commit implement workaround for such situation. > Then the stall detected EMAC will be restarted. > > On device the stall looks like the device lost it's dynamic IP address. > ifconfig shows that interface error counter rapidly increments. > At the same time on the DHCP server we can see continues DHCP-requests > from device. > > In real network stalls happen really rarely. To make them frequent the > broadcast storm[1] should be simulated. For simulation it is necessary > to make following connections: > 1. connect radxarock to 1st port of switch > 2. connect some PC to 2nd port of switch > 3. connect two other free ports together using standard ethernet cable, > in order to make a switching loop. > > After that, is necessary to make a broadcast storm. For example, running on > PC 'ping' to some IP address triggers ARP-request storm. After some > time (~10sec), EMAC on rk3188 will stall. > > Observed and tested on rk3188 radxarock. > > [1] https://en.wikipedia.org/wiki/Broadcast_radiation > > Signed-off-by: Alexander Kochetkov This patch doesn't apply cleanly to any of my trees.