From: Eric W. Biederman Date: Thu, 8 May 2008 21:41:00 +0000 (-0700) Subject: kobject: Fix kobject_rename and !CONFIG_SYSFS X-Git-Tag: v2.6.28-rc1~284^2~7 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=030c1d2bfcc2187650fb975456ca0b61a5bb77f4;p=linux-2.6-omap-h63xx.git kobject: Fix kobject_rename and !CONFIG_SYSFS When looking at kobject_rename I found two bugs with that exist when sysfs support is disabled in the kernel. kobject_rename does not change the name on the kobject when sysfs support is not compiled in. kobject_rename without locking attempts to check the validity of a rename operation, which the kobject layer simply does not have the infrastructure to do. This patch documents the previously unstated requirement of kobject_rename that is the responsibility of the caller to provide mutual exclusion and to be certain that the new_name for the kobject is valid. This patch modifies sysfs_rename_dir in !CONFIG_SYSFS case to call kobject_set_name to actually change the kobject_name. This patch removes the bogus and misleading check in kobject_rename that attempts to see if a rename is valid. The check is bogus because we do not have the proper locking. The check is misleading because it looks like we can and do perform checking at the kobject level that we don't. Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- diff --git a/Documentation/kobject.txt b/Documentation/kobject.txt index 51a8021ee53..f5d2aad65a6 100644 --- a/Documentation/kobject.txt +++ b/Documentation/kobject.txt @@ -118,6 +118,10 @@ the name of the kobject, call kobject_rename(): int kobject_rename(struct kobject *kobj, const char *new_name); +Note kobject_rename does perform any locking or have a solid notion of +what names are valid so the provide must provide their own sanity checking +and serialization. + There is a function called kobject_set_name() but that is legacy cruft and is being removed. If your code needs to call this function, it is incorrect and needs to be fixed. diff --git a/drivers/base/core.c b/drivers/base/core.c index 9649d1c422a..8c2cc2648f5 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1327,6 +1327,11 @@ EXPORT_SYMBOL_GPL(device_destroy); * device_rename - renames a device * @dev: the pointer to the struct device to be renamed * @new_name: the new name of the device + * + * It is the responsibility of the caller to provide mutual + * exclusion between two different calls of device_rename + * on the same device to ensure that new_name is valid and + * won't conflict with other devices. */ int device_rename(struct device *dev, char *new_name) { diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index b330e289d71..39924a96220 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -20,6 +20,8 @@ struct kobject; struct module; +extern int kobject_set_name(struct kobject *kobj, const char *name, ...) + __attribute__((format(printf, 2, 3))); /* FIXME * The *owner field is no longer used, but leave around * until the tree gets cleaned up fully. @@ -147,7 +149,7 @@ static inline void sysfs_remove_dir(struct kobject *kobj) static inline int sysfs_rename_dir(struct kobject *kobj, const char *new_name) { - return 0; + return kobject_set_name(kobj, "%s", new_name); } static inline int sysfs_move_dir(struct kobject *kobj, diff --git a/lib/kobject.c b/lib/kobject.c index fbf0ae28237..ae6bb900bfb 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -387,6 +387,11 @@ EXPORT_SYMBOL_GPL(kobject_init_and_add); * kobject_rename - change the name of an object * @kobj: object in question. * @new_name: object's new name + * + * It is the responsibility of the caller to provide mutual + * exclusion between two different calls of kobject_rename + * on the same kobject and to ensure that new_name is valid and + * won't conflict with other kobjects. */ int kobject_rename(struct kobject *kobj, const char *new_name) { @@ -401,19 +406,6 @@ int kobject_rename(struct kobject *kobj, const char *new_name) if (!kobj->parent) return -EINVAL; - /* see if this name is already in use */ - if (kobj->kset) { - struct kobject *temp_kobj; - temp_kobj = kset_find_obj(kobj->kset, new_name); - if (temp_kobj) { - printk(KERN_WARNING "kobject '%s' cannot be renamed " - "to '%s' as '%s' is already in existence.\n", - kobject_name(kobj), new_name, new_name); - kobject_put(temp_kobj); - return -EINVAL; - } - } - devpath = kobject_get_path(kobj, GFP_KERNEL); if (!devpath) { error = -ENOMEM;