Re: [PATCH v3] mac80211: redefine usage of the mac80211 workqueue

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

On Wed, Jul 29, 2009 at 1:00 PM, John W. Linville<linville@tuxdriver.com> wrote:
> On Mon, Jul 27, 2009 at 03:21:31PM -0700, Luis R. Rodriguez wrote:
>> The mac80211 workqueue exists to enable mac80211 and drivers
>> to queue their own work on a single threaded workqueue. mac80211
>> takes care to flush the workqueue during suspend but we never
>> really had requirements on drivers for how they should use
>> the workqueue in consideration for suspend.
>>
>> We extend mac80211 to document how the mac80211 workqueue should
>> be used, how it should not be used and finally move raw access to
>> the workqueue to mac80211 only. Drivers and mac80211 use helpers
>> to queue work onto the mac80211 workqueue:
>>
>>   * ieee80211_queue_work()
>>   * ieee80211_queue_delayed_work()
>>
>> These helpers will now warn if mac80211 already completed its
>> suspend cycle and someone is trying to queue work. mac80211
>> flushes the mac80211 workqueue prior to suspend a few times,
>> but we haven't taken the care to ensure drivers won't add more
>> work after suspend. To help with this we add a warning when
>> someone tries to add work and mac80211 already completed the
>> suspend cycle.
>>
>> Drivers should ensure they cancel any work or delayed work
>> in the mac80211 stop() callback.
>
> How are they supposed to do that after you've removed workqueue
> from the ieee80211_hw structure?

They do not refer to the mac80211 workqueue for that, they can cancel
work using cancel_work_sync(their_foo_work_struct).

> This breaks the compilation of
> at76c50x-usb.c...

Strange, I thought I tested that, will retest,

  Luis