On 2014/11/7 0:55, Tejun Heo wrote:
> Maybe "fix glue dir race condition by not removing them" is a better
> title?
Yes, it's better, thank you!
>
> On Thu, Nov 06, 2014 at 04:16:38PM +0800, Yijing Wang wrote:
>> There is a race condition when removing glue directory.
>> It can be reproduced in following test:
>>
>> path 1: Add first child device
>> device_add()
>> get_device_parent()
>> /*find parent from glue_dirs.list*/
>> list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
>> if (k->parent == parent_kobj) {
>> kobj = kobject_get(k);
>> break;
>> }
>> ....
>> class_dir_create_and_add()
>>
>> path2: Remove last child device under glue dir
>> device_del()
>> cleanup_device_parent()
>> cleanup_glue_dir()
>> kobject_put(glue_dir);
>>
>> If path2 has been called cleanup_glue_dir(), but not
>> call kobject_put(glue_dir), the glue dir is still
>> in parent's kset list. Meanwhile, path1 find the glue
>> dir from the glue_dirs.list. Path2 may release glue dir
>> before path1 call kobject_get(). So kernel will report
>> the warning and bug_on.
>>
>> This fix keep glue dir around once it created suggested
>> by Tejun Heo.
>
> I think you prolly want to explain why this is okay / desired.
> e.g. list how the glue dir is used and how many of them are there and
> explain that there's no real benefit in removing them.
>
Right, I will add the explanation. :)
> ...
>> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
>> Signed-off-by: Weng Meiling <wengmeiling.weng@xxxxxxxxxx>
>> Cc: <stable@xxxxxxxxxxxxxxx> #3.4+
>
> Except for the above nits.
>
> Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Thanks!
>
--
Thanks!
Yijing
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html