Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758305Ab2FFU0D (ORCPT ); Wed, 6 Jun 2012 16:26:03 -0400 Received: from mail-ee0-f46.google.com ([74.125.83.46]:41575 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752574Ab2FFU0A (ORCPT ); Wed, 6 Jun 2012 16:26:00 -0400 Subject: Re: [PATCH] virtio-net: fix a race on 32bit arches From: Eric Dumazet To: Ben Hutchings Cc: "Michael S. Tsirkin" , Stephen Hemminger , Jason Wang , netdev@vger.kernel.org, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org In-Reply-To: <1339013979.2836.52.camel@bwh-desktop.uk.solarflarecom.com> References: <1338971724.2760.3913.camel@edumazet-glaptop> <1338972341.2760.3944.camel@edumazet-glaptop> <20120606111357.GA15070@redhat.com> <1338988210.2760.4485.camel@edumazet-glaptop> <20120606144941.GA17092@redhat.com> <20120606081432.6b602065@nehalam.linuxnetplumber.net> <20120606185107.GA20503@redhat.com> <1339012441.26966.48.camel@edumazet-glaptop> <20120606195814.GA20677@redhat.com> <1339013289.26966.62.camel@edumazet-glaptop> <1339013979.2836.52.camel@bwh-desktop.uk.solarflarecom.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 06 Jun 2012 22:25:57 +0200 Message-ID: <1339014357.26966.72.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1001 Lines: 28 On Wed, 2012-06-06 at 21:19 +0100, Ben Hutchings wrote: > On Wed, 2012-06-06 at 22:08 +0200, Eric Dumazet wrote: > > On Wed, 2012-06-06 at 22:58 +0300, Michael S. Tsirkin wrote: > > > > > Absolutely, I am talking about virtio here. I'm not kicking > > > u64_stats_sync idea I am just saying that simple locking > > > would work for virtio and might be better as it > > > gives us a way to get counters atomically. > > > > Which lock do you own in the RX path ? > > > > You'll have to add a lock in fast path. This sounds really a bad choice > > to me. > > You have the NAPI 'lock', so when gathering stats you can synchronise > using napi_disable() ;-) Nice, this adds one new bug in network stack. Really guys, can we stop this thread, please ? -- 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/