Messages in this thread | | | Date | Thu, 16 May 2013 12:48:43 +0800 | From | Chen Gang <> | Subject | Re: [PATCH] kernel/workqueue.c: need call device_remove_file() when failure occurs after called device_create_file() |
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On 05/16/2013 12:16 PM, Chen Gang wrote: > On 05/16/2013 11:33 AM, Chen Gang wrote: >> On 05/16/2013 05:22 AM, Tejun Heo wrote: >>> On Wed, May 15, 2013 at 02:13:14PM +0800, Chen Gang wrote: >>>> >>>> In workqueue_sysfs_register(), when failure occurs after called >>>> device_create_file(), need call device_remove_file() to release the >>>> related resources, then call device_unregister(). >>>> >>>> Or it will cause issue. >>>> >>>> For individual 'device_attributs' (just like our case), need call >>>> device_remove_file() explictly and then call device_unregister(), >>>> please reference drivers/base/*.c (e.g node.c or cpu.c). >>> >>> Hmm... isn't this already taken care of by __sysfs_remove_dir() which >>> device_unregister() calls? That function removes all non-directory >>> files under the directory being removed. >>> >>
__sysfs_remove_dir() remove all related things, but not deref the count.
For __sysfs_remove_dir() -> ... sysfs_addrm_start() ... while() { ... sysfs_remove_one() (not deref the related file) } sysfs_addrm_finish() (will deref current dir)
For device_remove_file() -> sysfs_remove_file() -> sysfs_hash_and_remove() -> ... sysfs_addrm_start() ... sysfs_remove_one() (not deref the current file) sysfs_addrm_finish() (will deref current file)
So if not call device_remove_file() firstly, the all files under the directory are removed, but the related resources are not released which will cause resource leak.
Thanks.
>> It just like what you said: >> device_unregister() -> >> kobject_del() -> >> sysfs_remove_dir() -> >> __sysfs_remove_dir() -> >> sysfs_remove_one() >> But: >> device_remove_file() -> >> sysfs_remove_file() -> >> ... >> sysfs_attr_ns() -> >> ops->namespace() (such as device_namespace() in workqueue.c) >> ... >> sysfs_hash_and_remove() -> >> sysfs_remove_one(). >> >> So if not call device_remove_file() explicitly, the device_namespace() >> may be not called. >> > > It seems, if not call ops->namespace(), it still is OK. To get a result, > it still has much details to continue to read. > > But all together, reference the related code of another subsystems, we > really need device_remove_file() before call device_unregister(). > > >> >> Even in device_unregister(), it still call device_remove_file() to >> release the related attributes firstly, then call kobject_del(). >> >> >> >> Thanks. >> > >
-- Chen Gang
Asianux Corporation
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