Re: [PATCH 6/6] cfg80211: move regulatory hints to workqueue

["Luis R. Rodriguez" <lrodriguez@atheros.com>]

On Thu, Feb 12, 2009 at 11:17 PM, Johannes Berg
<johannes@sipsolutions.net> wrote:
> On Thu, 2009-02-12 at 23:14 -0800, Luis R. Rodriguez wrote:
>
>> >>> Yes, but I need to look at the one Reinette posted and fix that one,
>> >>> which will probably require a different solution.
>> >>
>> >> Oh I didn't see that one. How different?
>> >
>> > I see an rtnl lock issue against scanning and the drv mutex. Doesn't
>> > seem to be related to regulatory. So how would that affect a path to
>> > move hints to a workqueue?
>>
>> Oh you mean the rntl_lock() and drv mutex is _still_ an issue?
>
> Well, regardless of regulatory, we now have two paths:
>
> nl80211: cfg80211_mutex  -->  drv->mutex  -->  rtnl
> wext:    rtnl  -->  cfg80211_mutex  -->  drv->mutex
>
> which is clearly not a good plan.
>
> Therefore, I'll probably have to implement solution (1) from what I sent
> you, and invert the locking in nl80211. That would fix your the
> immediate problem with regulatory as well, because that was:
>
> rtnl  --->  (regulatory_hint) --->  cfg80211_mutex  -->  drv->mutex

Yup I see. So as it stands in this patch user reg hint now is:

reg_mutex --> cfg80211_mutex

Driver hint also does the same so it seems your fix on nl80211 would
probably just tap this series on the nl80211_req_set_reg().

I also think using a workqueue would be good here anyway, the only
negative thing I've seen is loading takes a bit longer.

  Luis