From 1e9a51dca19dc1d8807c63cb3bd4413d3f95aaf5 Mon Sep 17 00:00:00 2001 From: Atsushi Nemoto Date: Fri, 26 Jan 2007 00:56:54 -0800 Subject: [PATCH] [PATCH] 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 Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/spi/spi.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 270e6211c2e..6307428d2c9 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -366,7 +366,6 @@ spi_alloc_master(struct device *dev, unsigned size) 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; + struct class_device *cdev; + struct spi_master *master = NULL; + struct spi_master *m; - 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; + 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);