From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751894AbdIOV0Z (ORCPT ); Fri, 15 Sep 2017 17:26:25 -0400 Received: from shards.monkeyblade.net ([184.105.139.130]:57290 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751705AbdIOV0X (ORCPT ); Fri, 15 Sep 2017 17:26:23 -0400 Date: Fri, 15 Sep 2017 14:26:22 -0700 (PDT) Message-Id: <20170915.142622.1357636170906048191.davem@davemloft.net> To: geert+renesas@glider.be Cc: steve.glendinning@shawell.net, andrew@lunn.ch, f.fainelli@gmail.com, netdev@vger.kernel.org, linux-pm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] net: smsc911x: Quieten netif during suspend From: David Miller In-Reply-To: <1505324525-9998-1-git-send-email-geert+renesas@glider.be> References: <1505324525-9998-1-git-send-email-geert+renesas@glider.be> X-Mailer: Mew version 6.7 on Emacs 25.2 / 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]); Fri, 15 Sep 2017 14:26:23 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Geert Uytterhoeven Date: Wed, 13 Sep 2017 19:42:05 +0200 > If the network interface is kept running during suspend, the net core > may call net_device_ops.ndo_start_xmit() while the Ethernet device is > still suspended, which may lead to a system crash. > > E.g. on sh73a0/kzm9g and r8a73a4/ape6evm, the external Ethernet chip is > driven by a PM controlled clock. If the Ethernet registers are accessed > while the clock is not running, the system will crash with an imprecise > external abort. > > As this is a race condition with a small time window, it is not so easy > to trigger at will. Using pm_test may increase your chances: > > # echo 0 > /sys/module/printk/parameters/console_suspend > # echo platform > /sys/power/pm_test > # echo mem > /sys/power/state > > To fix this, make sure the network interface is quietened during > suspend. > > Signed-off-by: Geert Uytterhoeven Applied.