From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932983AbXAWQHp (ORCPT ); Tue, 23 Jan 2007 11:07:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933013AbXAWQHp (ORCPT ); Tue, 23 Jan 2007 11:07:45 -0500 Received: from mba.ocn.ne.jp ([210.190.142.172]:64697 "EHLO smtp.mba.ocn.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932983AbXAWQHo (ORCPT ); Tue, 23 Jan 2007 11:07:44 -0500 Date: Wed, 24 Jan 2007 01:07:41 +0900 (JST) Message-Id: <20070124.010741.130240814.anemo@mba.ocn.ne.jp> To: david-b@pacbell.net Cc: linux-kernel@vger.kernel.org, hcegtvedt@atmel.com, akpm@osdl.org Subject: Re: [PATCH 2.6.20-rc5] SPI: alternative fix for spi_busnum_to_master From: Atsushi Nemoto In-Reply-To: <200701230742.15531.david-b@pacbell.net> References: <200701221412.02452.david-b@pacbell.net> <20070123.101011.25910575.nemoto@toshiba-tops.co.jp> <200701230742.15531.david-b@pacbell.net> X-Fingerprint: 6ACA 1623 39BD 9A94 9B1A B746 CA77 FE94 2874 D52F X-Pgp-Public-Key: http://wwwkeys.pgp.net/pks/lookup?op=get&search=0x2874D52F X-Mailer: Mew version 3.3 on Emacs 21.4 / Mule 5.0 (SAKAKI) 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 On Tue, 23 Jan 2007 07:42:15 -0800, David Brownell wrote: > > Indeed the check can be omitted. Should I send a new patch just > > moving class_device_get() into "if (master->bus_num == bus_num)" > > block? > > Yes, please. OK, here is. This patch uses spi_master_get() instead of class_device_get(). Subject: SPI: alternative fix for spi_busnum_to_master If a SPI master device exists, udev (udevtrigger) causes kernel crash, due to wrong kobj pointer in kobject_uevent_env(). This problem was not in 2.6.19. The backtrace (on MIPS) was: [<8024db6c>] kobject_uevent_env+0x54c/0x5e8 [<802a8264>] store_uevent+0x1c/0x3c (in drivers/class.c) [<801cb14c>] subsys_attr_store+0x2c/0x50 [<801cb80c>] flush_write_buffer+0x38/0x5c [<801cb900>] sysfs_write_file+0xd0/0x190 [<80181444>] vfs_write+0xc4/0x1a0 [<80181cdc>] sys_write+0x54/0xa0 [<8010dae4>] stack_done+0x20/0x3c flush_write_buffer() passes kobject of spi_master_class.subsys to subsys_addr_store(), then subsys_addr_store() passes a pointer to a struct subsystem to store_uevent() which expects a pointer to a struct class_device. The problem seems subsys_attr_store() called instead of class_device_attr_store(). This mismatch was caused by commit 3bd0f6943520e459659d10f3282285e43d3990f1, which overrides kset of master class. This made spi_master_class.subsys.kset.ktype NULL so subsys_sysfs_ops is used instead of class_dev_sysfs_ops. The commit was to fix spi_busnum_to_master(). Here is a patch fixes this function in other way, just searching children list of class_device. Signed-off-by: Atsushi Nemoto --- diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 270e621..6307428 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -366,7 +366,6 @@ spi_alloc_master(struct device *dev, uns class_device_initialize(&master->cdev); master->cdev.class = &spi_master_class; - kobj_set_kset_s(&master->cdev, spi_master_class.subsys); master->cdev.dev = get_device(dev); spi_master_set_devdata(master, &master[1]); @@ -466,14 +465,20 @@ EXPORT_SYMBOL_GPL(spi_unregister_master) */ struct spi_master *spi_busnum_to_master(u16 bus_num) { - char name[9]; - struct kobject *bus; - - snprintf(name, sizeof name, "spi%u", bus_num); - bus = kset_find_obj(&spi_master_class.subsys.kset, name); - if (bus) - return container_of(bus, struct spi_master, cdev.kobj); - return NULL; + struct class_device *cdev; + struct spi_master *master = NULL; + struct spi_master *m; + + down(&spi_master_class.sem); + list_for_each_entry(cdev, &spi_master_class.children, node) { + m = container_of(cdev, struct spi_master, cdev); + if (m->bus_num == bus_num) { + master = spi_master_get(m); + break; + } + } + up(&spi_master_class.sem); + return master; } EXPORT_SYMBOL_GPL(spi_busnum_to_master);