Re: [PATCH v2] wireless: Allow registering more than one beacon listener.

[Felix Fietkau <nbd@openwrt.org>]

On 2012-10-29 5:26 PM, Johannes Berg wrote:
> On Mon, 2012-10-29 at 09:17 -0700, Ben Greear wrote:
> 
>> >> +	spin_lock_bh(&rdev->beacon_registrations_lock);
>> > ...
>> >> +	spin_unlock_bh(&rdev->beacon_registrations_lock);
>> >
>> > I have a feeling this is incorrect, this is called with BHs disabled, so
>> > if we disable/enable BHs here we end up with BHs enabled even if the
>> > caller wanted them disabled, no?
>> >
>> > So I suppose unless we need to be able to call this from hard interrupt
>> > in some driver (unlikely) we should add a change like this:
>> 
>> I get confused with the various types of spin-locks,
>> and I just copied this code from the mgt frames logic.
> 
> Uh, that looks like a bug there as well then?
As far as I know, local_bh_enable/local_bh_disable (which are used by
spin_lock_bh) are re-entrant. Using them from a BH-disabled context is
safe. All I can find with a few simple google searches confirms this.

- Felix