From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] net: fix race in process_backlog Date: Wed, 3 Oct 2007 15:05:19 -0700 Message-ID: <20071003150519.1fd206a8@freepuppy.rosehill> References: <1191426293.5599.27.camel@lappy> <20071003.145807.111205634.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jdike@addtoit.com To: David Miller Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:47162 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754130AbXJCWFc (ORCPT ); Wed, 3 Oct 2007 18:05:32 -0400 In-Reply-To: <20071003.145807.111205634.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 03 Oct 2007 14:58:07 -0700 (PDT) David Miller wrote: > From: Peter Zijlstra > Date: Wed, 03 Oct 2007 17:44:53 +0200 > > > Index: linux-2.6/net/core/dev.c > > =================================================================== > > --- linux-2.6.orig/net/core/dev.c > > +++ linux-2.6/net/core/dev.c > > @@ -2095,11 +2095,11 @@ static int process_backlog(struct napi_s > > > > local_irq_disable(); > > skb = __skb_dequeue(&queue->input_pkt_queue); > > - local_irq_enable(); > > if (!skb) { > > - napi_complete(napi); > > + __napi_complete(napi); > > break; > > } > > + local_irq_enable(); > > What re-enables interrupts in the !skb path? This looks like a better fix. the irq_enable is needed in both cases. --- a/net/core/dev.c 2007-09-27 07:19:10.000000000 -0700 +++ b/net/core/dev.c 2007-10-03 15:03:54.000000000 -0700 @@ -2077,12 +2077,14 @@ static int process_backlog(struct napi_s local_irq_disable(); skb = __skb_dequeue(&queue->input_pkt_queue); - local_irq_enable(); if (!skb) { - napi_complete(napi); + __napi_complete(napi); + local_irq_enable(); break; } + local_irq_enable(); + dev = skb->dev; netif_receive_skb(skb); -- Stephen Hemminger