Re: [PATCH RFC] workqueue: remove in_workqueue_context()

[Tejun Heo <tj@kernel.org>]

On 09/23/2010 07:10 PM, Paul E. McKenney wrote:
> On Thu, Sep 23, 2010 at 02:35:07PM +0200, Tejun Heo wrote:
>> Commit a25909a4 (lockdep: Add an in_workqueue_context() lockdep-based
>> test function) added in_workqueue_context() but there hasn't been any
>> in-kernel user and the lockdep annotation in workqueue is scheduled to
>> change.  Remove the unused function.
>>
>> Signed-off-by: Tejun Heo <tj@kernel.org>
>> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>> ---
>> Paul, I was looking through lockdep annotations to see how they can be
>> improved and noticed that in_workqueue_context() isn't used by anyone
>> and it seems like there hasn't been any in-kernel user either.  Can
>> this be removed or do you expect to use it somewhere?
> 
> I added it for the drivers/vhost changes.  They were using a
> variant of RCU where executing in workqueue context acted as an RCU
> read-side critical section and where flushing workqueues acted as
> an RCU grace period.  The in_workqueue_context() was then passed to
> rcu_dereference_check() to verify correct usage.
> 
> But you are right, I don't see it being used any more, though I do still
> see the big block comment documenting this in drivers/vhost/vhost.h.
> 
> Michael, what are Tejun and I missing here?

Ping.  Shall I go forward with this patch?

Thanks.

-- 
tejun