Re: [BUG] act_ife: sleeping functions called in atomic context

From: Cong Wang
Date: Thu Jun 16 2016 - 17:44:13 EST

On Thu, Jun 16, 2016 at 1:50 PM, Alexey Khoroshilov
<khoroshilov@xxxxxxxxx> 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.

> -> 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?