From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jussi Kivilinna Subject: Re: [PATCH] net/usb: rtl8150: allocate URB transfer_buffer and setup_packet separately Date: Sat, 10 Aug 2013 10:38:19 +0300 Message-ID: <5205EDEB.3010707@iki.fi> References: <20130807133653.15587.35442.stgit@localhost6.localdomain6> <5203F4D4.8090609@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: netdev@vger.kernel.org, Greg Kroah-Hartman , linux-usb@vger.kernel.org, "David S. Miller" To: Petko Manolov Return-path: Received: from saarni.dnainternet.net ([83.102.40.136]:38398 "EHLO saarni.dnainternet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965460Ab3HJHi1 (ORCPT ); Sat, 10 Aug 2013 03:38:27 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 09.08.2013 21:50, Petko Manolov wrote: > On Thu, 8 Aug 2013, Jussi Kivilinna wrote: > >> On 08.08.2013 18:14, Petko Manolov wrote: >>> On Wed, 7 Aug 2013, Jussi Kivilinna wrote: >>> >>>> rtl8150 allocates URB transfer_buffer and setup_packet as part of same >>>> structure 'struct async_req'. This can cause same cacheline to be >>>> DMA-mapped twice with same URB. This can lead to memory corruption on >>>> some systems. >>> >>> I can see performance impact due to the double mapping. However, memory >>> corruption seems a bit too much for sane cache and DMA controllers. Out >>> of interest - which is the architecture that will potentially corrupt the >>> memory. >> >> rtlwifi driver had similar structure to allocate both setup_packet and >> transfer_buffer in single go (overlapping dma-mapping cachelines) and >> this caused problems on ARM/sunxi. Problems means: memory corruptions at >> random locations, device freezes and lock-ups. > > Broken controllers?.. > At first I thought so too, but I discussed about this at linux-usb, and answer was that driver which uses same (dma/-)cacheline for multiple buffers is buggy.. http://marc.info/?l=linux-usb&m=137130407121137&w=2 (at end) http://marc.info/?l=linux-usb&m=137137080902265&w=2 http://marc.info/?l=linux-usb&m=137242422120782&w=2 -Jussi