Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757277Ab0BXQTd (ORCPT ); Wed, 24 Feb 2010 11:19:33 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:52351 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757263Ab0BXQTb (ORCPT ); Wed, 24 Feb 2010 11:19:31 -0500 Date: Wed, 24 Feb 2010 11:19:28 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Benjamin Herrenschmidt cc: Catalin Marinas , Matthew Dharm , , 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 Subject: Re: USB mass storage and ARM cache coherency In-Reply-To: <1266979632.23523.1668.camel@pasglop> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 957 Lines: 21 On Wed, 24 Feb 2010, Benjamin Herrenschmidt wrote: > > The PIO HCD drivers, however, don't call flush_dcache_page(). Is it possible > > that the HCD could transfer data into a page cache page already mapped > > in user space? My understanding is that the scenario above is possible. > > 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. Alan Stern -- 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/