Messages in this thread Patch in this message | | | Date | Mon, 22 Jan 2007 11:25:09 +0900 (JST) | Subject | Re: [PATCH 2.6.20-rc5] SPI: alternative fix for spi_busnum_to_master | From | Atsushi Nemoto <> |
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On Thu, 18 Jan 2007 20:28:49 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote: > 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.
Here is a revised version. The children list of spi_master_class contains only spi_master class so we can just compare bus_num member instead of class_id string.
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 <anemo@mba.ocn.ne.jp> --- diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 270e621..88c945b 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 +465,22 @@ 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; + + down(&spi_master_class.sem); + list_for_each_entry(cdev, &spi_master_class.children, node) { + cdev = class_device_get(cdev); + if (!cdev) + continue; + master = container_of(cdev, struct spi_master, cdev); + if (master->bus_num == bus_num) + break; + master = NULL; + class_device_put(cdev); + } + up(&spi_master_class.sem); + return master; } EXPORT_SYMBOL_GPL(spi_busnum_to_master); - 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/
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