Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752387Ab0DLPji (ORCPT ); Mon, 12 Apr 2010 11:39:38 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:59686 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751999Ab0DLPjh convert rfc822-to-8bit (ORCPT ); Mon, 12 Apr 2010 11:39:37 -0400 Date: Mon, 12 Apr 2010 08:38:42 -0700 From: Stephen Hemminger To: Eric Dumazet Cc: Cong Wang , Jay Vosburgh , Neil Horman , netdev@vger.kernel.org, Matt Mackall , bridge@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Miller , Jeff Moyer , Andy Gospodarek , bonding-devel@lists.sourceforge.net Subject: Re: [Bonding-devel] [v3 Patch 2/3] bridge: make bridge support netpoll Message-ID: <20100412083842.26d71bda@nehalam> In-Reply-To: <1271068737.16881.18.camel@edumazet-laptop> References: <20100408062234.4499.17042.sendpatchset@localhost.localdomain> <20100408062246.4499.5670.sendpatchset@localhost.localdomain> <20100408083710.2b61ee44@nehalam> <4BC2F7E2.7020309@redhat.com> <1271068737.16881.18.camel@edumazet-laptop> Organization: Linux Foundation X-Mailer: Claws Mail 3.7.5 (GTK+ 2.18.3; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 42 On Mon, 12 Apr 2010 12:38:57 +0200 Eric Dumazet wrote: > Le lundi 12 avril 2010 à 18:37 +0800, Cong Wang a écrit : > > Stephen Hemminger wrote: > > > There is no protection on dev->priv_flags for SMP access. > > > It would better bit value in dev->state if you are using it as control flag. > > > > > > Then you could use > > > if (unlikely(test_and_clear_bit(__IN_NETPOLL, &skb->dev->state))) > > > netpoll_send_skb(...) > > > > > > > > > > Hmm, I think we can't use ->state here, it is not for this kind of purpose, > > according to its comments. > > > > Also, I find other usages of IFF_XXX flags of ->priv_flags are also using > > &, | to set or clear the flags. So there must be some other things preventing > > the race... > > Yes, its RTNL that protects priv_flags changes, hopefully... > The patch was not protecting priv_flags with RTNL. For example.. @@ -308,7 +312,9 @@ static void netpoll_send_skb(struct netp tries > 0; --tries) { if (__netif_tx_trylock(txq)) { if (!netif_tx_queue_stopped(txq)) { + dev->priv_flags |= IFF_IN_NETPOLL; status = ops->ndo_start_xmit(skb, dev); + dev->priv_flags &= ~IFF_IN_NETPOLL; if (status == NETDEV_TX_OK) txq_trans_update(txq); -- 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/