Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754458Ab0ATUcO (ORCPT ); Wed, 20 Jan 2010 15:32:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754129Ab0ATUcN (ORCPT ); Wed, 20 Jan 2010 15:32:13 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:60793 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752638Ab0ATUcM (ORCPT ); Wed, 20 Jan 2010 15:32:12 -0500 Date: Wed, 20 Jan 2010 12:30:33 -0800 From: Stephen Hemminger To: "Michael Chan" Cc: "Jarek Poplawski" , "David Miller" , "Michael Breuer" , "akpm@linux-foundation.org" , "flyboy@gmail.com" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "Don Fry" , "Francois Romieu" , "Matthew Carlson" Subject: Re: [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync Message-ID: <20100120123033.0746b11e@nehalam> In-Reply-To: <1264018312.9030.76.camel@nseg_linux_HP1.broadcom.com> References: <20100120094103.GA6225@ff.dom.local> <20100120100316.2b5b1b05@nehalam> <1264018312.9030.76.camel@nseg_linux_HP1.broadcom.com> Organization: Linux Foundation X-Mailer: Claws Mail 3.7.2 (GTK+ 2.18.3; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1694 Lines: 38 On Wed, 20 Jan 2010 12:11:52 -0800 "Michael Chan" wrote: > > On Wed, 2010-01-20 at 10:03 -0800, Stephen Hemminger wrote: > > On Wed, 20 Jan 2010 09:41:03 +0000 > > Jarek Poplawski wrote: > > > > Seems like an underlying bug in the DMA api. Maybe it just can't > > > > handle operations on partial mapping. > > > > > > > > Other drivers with same problem: > > > > bnx2, cassini, pcnet32, r8169, rrunner, skge, sungem, tg3, > > > > > > It seems using the same length (even without pci_unmap_len()) is > > > crucial here, but I hope maintainers (added to CC) will take care. > > > > > I'm still unsure how to do dma_sync properly in bnx2. In the current > code, we always dma_sync_for_cpu a small portion of the SKB because the > rx descriptor is at the beginning of the SKB. We get the packet length, > for example, from the rx descriptor. > > If it's a big packet, we'll simply unmap the entire SKB buffer (with the > beginning portion already dma_sync'ed). If the packet is smaller than > what we dma_sync'ed, we'll just copy the data to a new SKB. We'll then > dma_sync_for_device the portion of the original buffer and recycle the > whole buffer back to the device for new packets. > > So, is it correct to just change the dma_sync length to the full length > of the buffer? It doesn't sound right to me. It looks like the size passed to sync_single has to match size of original mapping. -- 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/