Re: ieee80211_scan_completed() calling config() and possible deadlock

[Kalle Valo <kalle.valo@iki.fi>]

Michael Buesch <mb@bu3sch.de> writes:

>> I'm just wondering what's the right way(tm) to handle this. I see
>> two options:
>> 
>> 1. Consider the (possible) deadlock as a feature, document it and
>> let the drivers handle it. This is relatively easy.
>> 
>> 2. Handle this in mac80211 (eg. schedule a workqueue) and drivers
>> don't need to care. This might complicate mac80211 implementation a
>> bit, but easier for the drivers.
>> 
>> I myself cannot decide which one is better. What do people think?
>> 
>
> I think drivers should not be able to call ieee80211_scan_completed()
> directly. Instead they should call a function which schedules
> ieee80211_scan_completed() on a workqueue.

Yes, that was my option two.

> In general I consider it broken behavior, if a function called by
> the driver can recurse into the driver. We had that behavior in
> ieee80211-softmac and it was one of the main reasons it sucked so
> much.

Ok, this is a very strong argument in favor of option 2.

> The wq schedule code is trivial to implement in mac80211 and it's also
> OK to do so. The function is not required to execute synchronously.

I'm leaning on option two then. Thanks for the feedback!

-- 
Kalle Valo