From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161136AbWHAGMm (ORCPT ); Tue, 1 Aug 2006 02:12:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161142AbWHAGMm (ORCPT ); Tue, 1 Aug 2006 02:12:42 -0400 Received: from dsl027-180-168.sfo1.dsl.speakeasy.net ([216.27.180.168]:6610 "EHLO sunset.davemloft.net") by vger.kernel.org with ESMTP id S1161136AbWHAGMl (ORCPT ); Tue, 1 Aug 2006 02:12:41 -0400 Date: Mon, 31 Jul 2006 23:11:58 -0700 (PDT) Message-Id: <20060731.231158.91311705.davem@davemloft.net> To: dan.j.williams@intel.com Cc: linux-kernel@vger.kernel.org, neilb@suse.de, galak@kernel.crashing.org, christopher.leech@intel.com, alan@lxorguk.ukuu.org.uk Subject: Re: [PATCH rev2 1/4] dmaengine: enable mutliple clients and operations From: David Miller In-Reply-To: <20060728181618.5948.27138.stgit@dwillia2-linux.ch.intel.com> References: <20060728181618.5948.27138.stgit@dwillia2-linux.ch.intel.com> X-Mailer: Mew version 4.2 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Can I ask that the known bugs in the I/O AT DMA code be fixed before we start adding new features to it? Specifically, the lock_cpu_hotplug() call in net_dma_rebalance() is still there and being invoked with a spinlock held. The spinlock is grabbed by the caller, netdev_dma_event() which grabs the net_dma_event_lock spinlock. You cannot invoke lock_cpu_hotplug() while holding a spinlock because lock_cpu_hotplug(), as seen in kernel/cpu.c, takes a semaphore which can sleep. Sleeping while holding a spinlock is not allowed. This is the second time I have tried to make the Intel developers aware of this bug. So please fix this problem. Thanks a lot.