Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933969Ab3CSUbl (ORCPT ); Tue, 19 Mar 2013 16:31:41 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:47430 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757343Ab3CSUbi (ORCPT ); Tue, 19 Mar 2013 16:31:38 -0400 Message-ID: <1363725088.3937.387.camel@deadeye.wl.decadent.org.uk> Subject: Re: [ 45/82] USB: EHCI: dont check DMA values in QH overlays From: Ben Hutchings To: Alan Stern Cc: stable@vger.kernel.org, akpm@linux-foundation.org, Joseph Salisbury , Greg Kroah-Hartman , LKML Date: Tue, 19 Mar 2013 20:31:28 +0000 In-Reply-To: References: Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-id3N8bnucTz6dr/VL5AK" X-Mailer: Evolution 3.4.4-2 Mime-Version: 1.0 X-SA-Exim-Connect-IP: 2001:470:1f08:1539:5944:e226:2c7e:1b17 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3590 Lines: 89 --=-id3N8bnucTz6dr/VL5AK Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2013-03-19 at 11:27 -0400, Alan Stern wrote: > On Tue, 19 Mar 2013, Ben Hutchings wrote: >=20 > > On Mon, 2013-03-18 at 04:22 +0000, Ben Hutchings wrote: > > > 3.2-stable review patch. If anyone has any objections, please let me= know. > > >=20 > > > ------------------ > > >=20 > > > From: Alan Stern > > >=20 > > > commit feca7746d5d9e84b105a613b7f3b6ad00d327372 upstream. > > >=20 > > > This patch (as1661) fixes a rather obscure bug in ehci-hcd. In a > > > couple of places, the driver compares the DMA address stored in a QH'= s > > > overlay region with the address of a particular qTD, in order to see > > > whether that qTD is the one currently being processed by the hardware= . > > > (If it is then the status in the QH's overlay region is more > > > up-to-date than the status in the qTD, and if it isn't then the > > > overlay's value needs to be adjusted when the QH is added back to the > > > active schedule.) > > >=20 > > > However, DMA address in the overlay region isn't always valid. It > > > sometimes will contain a stale value, which may happen by coincidence > > > to be equal to a qTD's DMA address. Instead of checking the DMA > > > address, we should check whether the overlay region is active and > > > valid. The patch tests the ACTIVE bit in the overlay, and clears thi= s > > > bit when the overlay becomes invalid (which happens when the > > > currently-executing URB is unlinked). > > >=20 > > > This is the second part of a fix for the regression reported at: > > >=20 > > > https://bugs.launchpad.net/bugs/1088733 > >=20 > > Alan, the first part (commit 6402c796d3b4 aka as1660) didn't apply and = I > > couldn't see how to adapt it for 3.2. Does this second part have any > > value without the first? Or, if you could provide a backport of the > > first part, that would be very much appreciated. >=20 > Without the first part, the second part can actually be dangerous. =20 > Under the circumstances, I think it is best to apply neither. Thanks, I've dropped this. Ben. --=20 Ben Hutchings When you say `I wrote a program that crashed Windows', people just stare ..= . and say `Hey, I got those with the system, *for free*'. - Linus Torvalds --=-id3N8bnucTz6dr/VL5AK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIVAwUAUUjLIOe/yOyVhhEJAQpJzxAAsdKsVMdm5z4ya38m/13ezBoV+LGXj7x/ QK4LSKBx+pD69vEXJ3oVt5jfOM+u7cT+eUEVF73yrS8rsR/ILVQNJGPuc4binJfn PEGw/XryTfVfvBCkxu/nSue7KnfoTt5xwjo/9l7VNP8ekUVMlvrC04Cz0RPVvOOM o5Dv4+3ggocnzsp34sBljzD5xi/Z4RMLjLUQlqvEbty9BI4EP572byo02zd7R8cy qjiiXAVbuUQKAQg4G/US+S+YNiz5cqch7Kux0tFCPDpnSSClOwX/oji11abuqNuw CKATHMnPX6yu1E1Vw6SYFGfw9cPz0ejvq5J1k/I5jQf6rfLfQqhtbUwhNE9Jqk7n Lg94nnodv44MGip5ZXeKmvgbXA1h0naISkYCs8/uVRqZg2NCtaQKuNSmvgrRygR6 NffJS2FVX/9HHJREuLCTZqtMuzBS+pJ+H2pOLolJpZGEnf4rqsCfTUctvAAPxq7Y PfIdwrQcQ3UZDyNh3Y0Lali+hikZv8xvZayqa2yGc+j5emsoLuOqxSlOE0LDO98n 3tG/Gbpnn4WjmVNxV8qBc239J6tme7LftfwjZnlJ/BKMNErEDnuGFQ67gKJNA+bV k71Gl676qYeeWFCqMCFOja9uiGvD2+boxYvBVuvOF6WVLY+R0Qm/PL+k7Yl9Evcy WyB1jTNXNG8= =Yurc -----END PGP SIGNATURE----- --=-id3N8bnucTz6dr/VL5AK-- -- 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/