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

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

On Wed, Jul 29, 2009 at 1:45 PM, Luis R.
Rodriguez<lrodriguez@atheros.com> wrote:
> 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,

Oh ok, sorry about that this requires a patch which I thought I had
sent but it seems I didn't:

at76c50x-usb: remove unneeded flush_workqueue() at usb disconnect

Will send.

  Luis