From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [Bug 49151] New: NULL pointer dereference in pata_acpi Date: Sat, 3 Nov 2012 16:30:41 +0000 Message-ID: <20121103163041.6663201d@pyramind.ukuu.org.uk> References: <20121020120047.GC17563@liondog.tnic> <50841CFC.2030802@talktalk.net> <20121021165756.GA20642@liondog.tnic> <50856AA8.1000607@talktalk.net> <20121022202734.GA16169@liondog.tnic> <20121023110549.06f9c2e8@pyramind.ukuu.org.uk> <20121023101751.GA24656@liondog.tnic> <5087B4CA.1030502@talktalk.net> <20121024115746.3d41fce7@pyramind.ukuu.org.uk> <20121103042635.GA21829@liondog.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:37628 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756141Ab2KCQZw (ORCPT ); Sat, 3 Nov 2012 12:25:52 -0400 In-Reply-To: <20121103042635.GA21829@liondog.tnic> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Borislav Petkov Cc: phillip.wood@dunelm.org.uk, phillip.wood@talktalk.net, "Anton V. Boyarshinov" , bugzilla-daemon@bugzilla.kernel.org, linux-ide@vger.kernel.org, Jeff Garzik On Sat, 3 Nov 2012 05:26:35 +0100 Borislav Petkov wrote: > On Wed, Oct 24, 2012 at 11:57:46AM +0100, Alan Cox wrote: > > Which is an ATA layer bug - adev->dma_mode should never be called > > without a DMA mode in normal use. > > Ok, it looks like this would take a while to fix. > > Alan, what is your suggestion for a proper fix, uncomment XFER_PIO_SLOW > and drop to it with a big warning that ACPI is giving botched No. The proper fix is to find out how it got called with no DMA mode set. There is no reason ACPI can't return pure PIO answers. If it does however then the DMA mode setting call should not be made by the core libata code. Lots of our ATA driver code relies upon that so if it's actually what is happening that is what needs fixing. Alan