Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965235Ab0BZQAx (ORCPT ); Fri, 26 Feb 2010 11:00:53 -0500 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:60765 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965060Ab0BZQAw (ORCPT ); Fri, 26 Feb 2010 11:00:52 -0500 Subject: Re: USB mass storage and ARM cache coherency From: Catalin Marinas To: Benjamin Herrenschmidt Cc: Alan Stern , Matthew Dharm , linux-usb@vger.kernel.org, Russell King - ARM Linux , "Mankad,Maulik Ojas" , Sergei Shtylyov , Ming Lei , Sebastian Siewior , Oliver Neukum , linux-kernel , "Shilimkar,Santosh" , Pavel Machek , Greg KH , linux-arm-kernel , James Bottomley In-Reply-To: <1267046036.23523.1693.camel@pasglop> References: <1267046036.23523.1693.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Organization: ARM Limited Date: Fri, 26 Feb 2010 16:00:44 +0000 Message-ID: <1267200044.14703.31.camel@e102109-lin.cambridge.arm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 26 Feb 2010 16:00:45.0778 (UTC) FILETIME=[DB1FAB20:01CAB6FC] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1282 Lines: 28 On Wed, 2010-02-24 at 21:13 +0000, Benjamin Herrenschmidt wrote: > On Wed, 2010-02-24 at 11:19 -0500, Alan Stern wrote: > > > It is but I'm not confident the responsibility for doing that cleanup > > > is at the HCD level. That would impact a lot of HCD activities that > > > don't need such flushing since the use of the page is purely in-kernel. > > > > That's right. The HCD merely puts data wherever it's told to. It > > doesn't know whether the destination is in the page cache, in > > userspace, or anywhere else. The same is true for usb-storage. > > I'm surprised that usb-storage has an issue here. It shouldn't afaik, > since it's just a SCSI driver (or not anymore ?) and the BIO or > filesystems handle things there no ? I haven't seen a single call to > flush_dcache_page() in any of drivers/scsi, drivers/ata or drivers/ide > when I looked... The BIO or filesystem code don't call flush_dcache_page() either (well some do like cramfs or jffs but they decompress the data received from the block device). -- Catalin -- 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/