From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757407Ab2KWCfv (ORCPT ); Thu, 22 Nov 2012 21:35:51 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56818 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755980Ab2KWCfu (ORCPT ); Thu, 22 Nov 2012 21:35:50 -0500 Message-ID: <1353638130.4764.4.camel@deadeye.wl.decadent.org.uk> Subject: Re: [ 02/38] PCI/PM: Fix deadlock when unbinding device if parent in D3cold From: Ben Hutchings To: Greg Kroah-Hartman , Huang Ying Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, alan@lxorguk.ukuu.org.uk, Bjorn Helgaas , "Rafael J. Wysocki" , Zhang Yanmin Date: Fri, 23 Nov 2012 02:35:30 +0000 In-Reply-To: <20121122003904.516735571@linuxfoundation.org> References: <20121122003904.262382971@linuxfoundation.org> <20121122003904.516735571@linuxfoundation.org> Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-aGJAZ5fmvagHD/wvGDid" X-Mailer: Evolution 3.4.4-1 Mime-Version: 1.0 X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 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 --=-aGJAZ5fmvagHD/wvGDid Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2012-11-21 at 16:39 -0800, Greg Kroah-Hartman wrote: > 3.0-stable review patch. If anyone has any objections, please let me kno= w. >=20 > ------------------ >=20 > From: Huang Ying >=20 > commit 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e upstream. >=20 > If a PCI device and its parents are put into D3cold, unbinding the > device will trigger deadlock as follow: >=20 > - driver_unbind > - device_release_driver > - device_lock(dev) <--- previous lock here > - __device_release_driver > - pm_runtime_get_sync > ... > - rpm_resume(dev) > - rpm_resume(dev->parent) > ... > - pci_pm_runtime_resume > ... > - pci_set_power_state > - __pci_start_power_transition > - pci_wakeup_bus(dev->parent->subordinate) > - pci_walk_bus > - device_lock(dev) <--- deadlock here >=20 >=20 > If we do not do device_lock in pci_walk_bus, we can avoid deadlock. > Device_lock in pci_walk_bus is introduced in commit: > d71374dafbba7ec3f67371d3b7e9f6310a588808, corresponding email thread > is: https://lkml.org/lkml/2006/5/26/38. The patch author Zhang Yanmin > said device_lock is added to pci_walk_bus because: >=20 > Some error handling functions call pci_walk_bus. For example, PCIe > aer. Here we lock the device, so the driver wouldn't detach from the > device, as the cb might call driver's callback function. >=20 > So I fixed the deadlock as follows: >=20 > - remove device_lock from pci_walk_bus > - add device_lock into callback if callback will call driver's callback >=20 > I checked pci_walk_bus users one by one, and found only PCIe aer needs > device lock. [...] What about eeh_report_error() in arch/powerpc/platforms/pseries/eeh_driver.c? Also, is the deadlock even possible before this change in Linux 3.6? commit 448bd857d48e69b33ef323739dc6d8ca20d4cda7 Author: Huang Ying Date: Sat Jun 23 10:23:51 2012 +0800 PCI/PM: add PCIe runtime D3cold support Ben. --=20 Ben Hutchings Never attribute to conspiracy what can adequately be explained by stupidity= . --=-aGJAZ5fmvagHD/wvGDid 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) iQIVAwUAUK7g8ue/yOyVhhEJAQqvHg//UL/k6Lk7kSKbAdPo3VrEiOX8FKdKEXXP 2zW1D3GcoN/Y+UdWN36qA9Vwp746CjBeXTDsDAgSAXhxhYuz0Jz9zlU+AAJms+x+ 6IQ+9lLV1+9oiuXlk2nuz6H3GEXMTiUqpB3UWKYB9yAXPmvL4dav3azcPjTgaTkL E0Ofp7zpHe8aOJD0cPHIfLA8Okn2ZB+nFnbcRbUH5Xcgd6kNMwYIICfadBdgdbhy bgnm/avwIxBMeQeZOVGtw0M+F8elBixGjDH8Z6Bq717mnycbiOEt5+Je5B8/giQQ 0y8HV5yQzcMUHFNP1Gxwa8nOG0z91fbhoTCI1D+Uw7PjumRleLsb3eUhbL2Hhmge cJtF7wogWlfcXmwYOUb9XTnfp/lPa4xgDiKDw8klsJao5hWf4pLms2l4YOCiG7IQ YfBvudM6cb0798/QsfRAGjhyrb5G539ICOp8mhLoiCxCXMHZRRNo/yHOoqjSMqeW AjD3509KkgyJdCPpf9mR/VrqHEYXIGRPFwncU/gkTqumtKTIad9+hML3PXT4E4A2 Mamng5yzsNPAjon565x9riqBPKMSWZuRic+sX3LzuUmtoRQs9HKToKTVZkv9OxRV kt6YTQZ943ggc4kP64ZAcoW+c8DZZnWjrDO3++fHbr8Mx16t3Wcj/P3XzANyQXxj CL51l3SDFP8= =9b8P -----END PGP SIGNATURE----- --=-aGJAZ5fmvagHD/wvGDid--