Re: [PATCH 2/2] workqueue: create lockdep dependency in flush_work()

[Tejun Heo]

On Tue, Aug 21, 2018 at 02:03:17PM +0200, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@xxxxxxxxx>
> 
> In flush_work(), we need to create a lockdep dependency so that
> the following scenario is appropriately tagged as a problem:
> 
>   work_function()
>   {
>     mutex_lock(&mutex);
>     ...
>   }
> 
>   other_function()
>   {
>     mutex_lock(&mutex);
>     flush_work(&work); // or cancel_work_sync(&work);
>   }
> 
> This is a problem since the work might be running and be blocked
> on trying to acquire the mutex.
> 
> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>

This makes sense to me.  Did you notice any extra lockdep warnings
with this?

Thanks.

-- 
tejun