From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver Date: Fri, 13 Jul 2007 09:02:21 -0400 Message-ID: <1184331741.3402.13.camel@localhost.localdomain> References: <20070704132212.726923000@pademelon.sonytel.be> <20070704132346.591348000@pademelon.sonytel.be> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from hancock.steeleye.com ([71.30.118.248]:56561 "EHLO hancock.sc.steeleye.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758003AbXGMNCX (ORCPT ); Fri, 13 Jul 2007 09:02:23 -0400 In-Reply-To: <20070704132346.591348000@pademelon.sonytel.be> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Geert Uytterhoeven Cc: Paul Mackerras , Jens Axboe , Alessandro Rubini , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Geoff Levand On Wed, 2007-07-04 at 15:22 +0200, Geert Uytterhoeven wrote: > + kaddr = kmap_atomic(sgpnt->page, KM_USER0); > + if (!kaddr) > + return -1; > + len = sgpnt->length; > + if ((req_len + len) > buflen) { > + active = 0; > + len = buflen - req_len; > + } > + memcpy(kaddr + sgpnt->offset, buf + req_len, > len); > + kunmap_atomic(kaddr, KM_USER0); This isn't a SCSI objection, but this sequence appears several times in this driver. It's wrong for a non-PIPT architecture (and I believe the PS3 is VIPT) because you copy into the kernel alias for the page, which dirties the line in the cache of that alias (the user alias cache line was already invalidated). However, unless you flush the kernel alias to main memory, the user could read stale data. The way this is supposed to be done is to do a flush_kernel_dcache_page(kaddr) before doing the kunmap. Otherwise it looks OK from the SCSI point of view. James