On 16-06-16 05:43 PM, Cong Wang wrote:
> On Thu, Jun 16, 2016 at 1:50 PM, Alexey Khoroshilov
> <khoroshilov@ispras.ru> wrote:
>> tcf_ife_init() contains a big chunk of code executed with
>> ife->tcf_lock spinlock held. But that code contains several calls
>> to sleeping functions:
>>    populate_metalist() and use_all_metadata()
>>      -> add_metainfo()
>>        -> find_ife_oplist(metaid)
>>          -> read_lock()
>>          -> try_module_get(o->owner)
>>        -> kzalloc(sizeof(*mi), GFP_KERNEL);
>
> Hmm, we don't need to hold that spinlock when we create a new ife action,
> since we haven't inserted it yet. We do need it when we modify an existing
> one. So I am thinking if we can refactor that code to avoid spinlock
> whenever possible.
>

Does attached (compile tested) patch help?

>>        -> ops->alloc(mi, metaval);
>>        -> module_put(ops->owner);
>>    _tcf_ife_cleanup()
>>      -> module_put()
>>
>> The same problem is actual for tcf_ife_cleanup() as well.
>>
>
> Huh? Both module_put() and kfree() should not sleep, right?
>

I dont think there is any sleeping there ;->

cheers,
jamal