Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756414Ab2HNO4s (ORCPT ); Tue, 14 Aug 2012 10:56:48 -0400 Received: from webmail.solarflare.com ([12.187.104.25]:60776 "EHLO ocex02.SolarFlarecom.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756357Ab2HNO4p (ORCPT ); Tue, 14 Aug 2012 10:56:45 -0400 Message-ID: <1344956195.824.206.camel@deadeye.wl.decadent.org.uk> Subject: Re: [PATCH 3/5] net/mlx4_en: Call netif_carrier_off() after register_netdev() From: Ben Hutchings To: CC: , , , , , , , , Date: Tue, 14 Aug 2012 15:56:35 +0100 In-Reply-To: References: <1344940135-17079-1-git-send-email-shchepetkov@ispras.ru> <1344940135-17079-4-git-send-email-shchepetkov@ispras.ru> Organization: Solarflare Communications Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.3-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [88.96.1.126] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1517 Lines: 42 On Tue, 2012-08-14 at 12:36 +0000, Sathya.Perla@Emulex.Com wrote: > >-----Original Message----- > >From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org] On > >Behalf Of Ilya Shchepetkov > > > >For carrier detection to work properly when binding the driver with a > >cable unplugged, netif_carrier_off() should be called after > >register_netdev(), not before. > > > >Calling netif_carrier_off() before register_netdev() was causing the > >network interface to miss a linkwatch pending event leading to an > >inconsistent state if the link is not up when interface is initialized. > > ndo_open() may be called as soon register_netdev() completes... > When netif_carrier_off() is called *after* register_netdev(), isn't there > a possibility of a ndo_open()->netif_carrier_on() call racing this call, causing > incorrect results? Yes, you should use something like: rtnl_lock(); rc = register_netdevice(dev); if (rc) goto out_unlock; netif_carrier_off(dev); rtnl_unlock(); (Why do we even have register_netdev() when it's such an invitation to races?) Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. -- 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/