From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757355Ab0DOHfJ (ORCPT ); Thu, 15 Apr 2010 03:35:09 -0400 Received: from buzzloop.caiaq.de ([212.112.241.133]:50990 "EHLO buzzloop.caiaq.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752056Ab0DOHfH (ORCPT ); Thu, 15 Apr 2010 03:35:07 -0400 Date: Thu, 15 Apr 2010 09:35:01 +0200 From: Daniel Mack To: Pedro Ribeiro Cc: Alan Stern , linux-usb@vger.kernel.org, Andi Kleen , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Greg KH , alsa-devel@alsa-project.org Subject: Re: USB transfer_buffer allocations on 64bit systems Message-ID: <20100415073501.GY30807@buzzloop.caiaq.de> References: <20100414163637.GV30807@buzzloop.caiaq.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 14, 2010 at 06:21:05PM +0100, Pedro Ribeiro wrote: > On 14 April 2010 17:36, Daniel Mack wrote: > > No worries - I agree. But unfortunately, I'm out of ideas now, and my > > initial thoughts about what might cause the trouble were abviously not > > able to explain the issue. Does anyone see further steps of tracking > > this issue down? > > > > Thanks, > > Daniel > > > > Well if this is a dirty / dangerous hack, what about your first patch? > I've been testing it for days and has given me no problems. [For those who haven't followed all the discussions - this patch used usb_buffer_alloc() instead of kmalloc() in the audio USB driver] No, Alan is right. As long as we don't know what's going on, it shouldn't be fixed that way. There might be an update to all USB drivers to use a special allocation function in order to avoid DMA bounce buffers for non-64-bit aware host controllers, but that's certainly a second step. First, the bug that you see needs attention, and the longer you can reproduce it, the better :) Daniel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Mack Subject: Re: USB transfer_buffer allocations on 64bit systems Date: Thu, 15 Apr 2010 09:35:01 +0200 Message-ID: <20100415073501.GY30807@buzzloop.caiaq.de> References: <20100414163637.GV30807@buzzloop.caiaq.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from buzzloop.caiaq.de (buzzloop.caiaq.de [212.112.241.133]) by alsa0.perex.cz (Postfix) with ESMTP id 1B36E24152 for ; Thu, 15 Apr 2010 09:35:06 +0200 (CEST) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Pedro Ribeiro Cc: alsa-devel@alsa-project.org, Greg KH , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Andi Kleen , Alan Stern , akpm@linux-foundation.org List-Id: alsa-devel@alsa-project.org On Wed, Apr 14, 2010 at 06:21:05PM +0100, Pedro Ribeiro wrote: > On 14 April 2010 17:36, Daniel Mack wrote: > > No worries - I agree. But unfortunately, I'm out of ideas now, and my > > initial thoughts about what might cause the trouble were abviously not > > able to explain the issue. Does anyone see further steps of tracking > > this issue down? > > > > Thanks, > > Daniel > > > > Well if this is a dirty / dangerous hack, what about your first patch? > I've been testing it for days and has given me no problems. [For those who haven't followed all the discussions - this patch used usb_buffer_alloc() instead of kmalloc() in the audio USB driver] No, Alan is right. As long as we don't know what's going on, it shouldn't be fixed that way. There might be an update to all USB drivers to use a special allocation function in order to avoid DMA bounce buffers for non-64-bit aware host controllers, but that's certainly a second step. First, the bug that you see needs attention, and the longer you can reproduce it, the better :) Daniel