Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932152Ab2FFUTp (ORCPT ); Wed, 6 Jun 2012 16:19:45 -0400 Received: from webmail.solarflare.com ([12.187.104.25]:31392 "EHLO ocex02.SolarFlarecom.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757520Ab2FFUTo (ORCPT ); Wed, 6 Jun 2012 16:19:44 -0400 Message-ID: <1339013979.2836.52.camel@bwh-desktop.uk.solarflarecom.com> Subject: Re: [PATCH] virtio-net: fix a race on 32bit arches From: Ben Hutchings To: Eric Dumazet CC: "Michael S. Tsirkin" , Stephen Hemminger , Jason Wang , , , , Date: Wed, 6 Jun 2012 21:19:39 +0100 In-Reply-To: <1339013289.26966.62.camel@edumazet-glaptop> 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> Organization: Solarflare Communications Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-1.fc16) Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-Originating-IP: [10.17.20.137] X-TM-AS-Product-Ver: SMEX-10.0.0.1412-6.800.1017-18950.005 X-TM-AS-Result: No--15.276600-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1009 Lines: 28 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() ;-) 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/