Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752048AbXBRUaR (ORCPT ); Sun, 18 Feb 2007 15:30:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752051AbXBRUaQ (ORCPT ); Sun, 18 Feb 2007 15:30:16 -0500 Received: from smtp-100-sunday.nerim.net ([62.4.16.100]:4098 "EHLO kraid.nerim.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752048AbXBRUaP (ORCPT ); Sun, 18 Feb 2007 15:30:15 -0500 Date: Sun, 18 Feb 2007 21:30:20 +0100 From: Jean Delvare To: Greg Kroah-Hartman Cc: LKML , Dmitry Torokhov Subject: [PATCH] platform: reorder platform_device_del Message-Id: <20070218213020.5618eb98.khali@linux-fr.org> X-Mailer: Sylpheed version 2.2.10 (GTK+ 2.8.20; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2668 Lines: 65 In platform_device_del(), we currently delete the device resources first, then we delete the device itself. This causes a (minor) bug to occur when one unregisters a platform device before unregistering its platform driver, and the driver is requesting (in .probe()) and releasing (in .remove()) a resource of the device. The device resources are already gone by the time the driver gets the chance to release the resources it had been requesting, causing an error like: Trying to free nonexistent resource <0000000000000295-0000000000000296> If the platform driver is unregistered first, the problem doesn't occur, as the driver will have the opportunity to release the resources it had requested before the device resources themselves are released. It's a bit odd that unregistering the driver first or the device first doesn't lead to the same result. So I believe that we should delete the device first in platform_device_del(). I've searched the git history and found that it used to be the case before 2.6.8, but was changed here: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commitdiff;h=96ef7b3689936ee1e64b711511342026a8ce459c > 2004/07/14 16:09:44-07:00 dtor_core > [PATCH] Driver core: Fix OOPS in device_platform_unregister > > Driver core: platform_device_unregister should release resources first > and only then call device_unregister, otherwise if there > are no more references to the device it will be freed and > the fucntion will try to access freed memory. However we now have an explicit call to put_device() at the end of platform_device_unregister() so I guess the original problem no longer exists and it is safe to revert that change. Signed-off-by: Jean Delvare --- drivers/base/platform.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) --- linux-2.6.20.orig/drivers/base/platform.c 2007-02-04 19:44:54.000000000 +0100 +++ linux-2.6.20/drivers/base/platform.c 2007-02-18 19:38:09.000000000 +0100 @@ -299,13 +299,13 @@ void platform_device_del(struct platform int i; if (pdev) { + device_del(&pdev->dev); + for (i = 0; i < pdev->num_resources; i++) { struct resource *r = &pdev->resource[i]; if (r->flags & (IORESOURCE_MEM|IORESOURCE_IO)) release_resource(r); } - - device_del(&pdev->dev); } } EXPORT_SYMBOL_GPL(platform_device_del); -- Jean Delvare - 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/