From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758915AbXGQITV (ORCPT ); Tue, 17 Jul 2007 04:19:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752476AbXGQITA (ORCPT ); Tue, 17 Jul 2007 04:19:00 -0400 Received: from agminet01.oracle.com ([141.146.126.228]:29282 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752987AbXGQIS7 (ORCPT ); Tue, 17 Jul 2007 04:18:59 -0400 From: Olaf Kirch Organization: Oracle To: Linus Torvalds Subject: Re: [patch] revert: [NET]: Fix races in net_rx_action vs netpoll Date: Tue, 17 Jul 2007 10:16:25 +0200 User-Agent: KMail/1.9.1 Cc: David Miller , mingo@elte.hu, linux-kernel@vger.kernel.org References: <20070716091236.GA10718@elte.hu> <20070716.042640.18306462.davem@davemloft.net> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707171016.27358.olaf.kirch@oracle.com> X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 16 July 2007 23:40, Linus Torvalds wrote: > - The change seems to always set the LIST_FROZEN bit when calling > ->poll(), and at least on e1000, the NAPI poll() routine ends up doing > that netif_rx_complete(), so we're *guaranteed* to always take the > early exit and not do anything. That is only in the poll_napi case, where netpoll tries to push pending frames. The default caller for dev->poll() is net_rx_action. We only ever get into this particular code branch in poll_napi when the RX_SCHED bit is already set, ie someone put the device on the NAPI poll_list and raised the softirq. poll_napi is just doing manually what net_rx_action would do anyway once the softirq is serviced. > - The early return from netif_rx_complete() ends up meaning that an > edge-triggered interrupt isn't handled properly, and will this never > happen again, since it never goes away. Sorry, I may be sitting on my brain this morning, but I don't understand how skipping netif_rx_complete would affect ACKing of interrupts. Olaf -- Olaf Kirch | --- o --- Nous sommes du soleil we love when we play okir@lst.de | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax