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Re: [PATCH] gpu: drm: amd: amdkfd: Remove create_workqueue()

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On Fri, May 27, 2016 at 12:15:17AM +0530, Bhaktipriya Shridhar wrote:
> alloc_workqueue replaces deprecated create_workqueue().
> 
> kfd_process_wq is used for delay destruction. A work item embedded in
> kfd_process gets queued to kfd_process_wq and when it executes it
> destroys and frees the containing kfd_process and thus itself.
> 
> This requires a dedicated workqueue because a work item once queued, may
> get freed at any point of time and any external entity cannot
> flush the work item. So, in order to wait for such a work item,
> it needs to be put on a dedicated workqueue.
> 
> kfd_module_exit() calls kfd_process_destroy_wq which ensures that all
> pending work items are finished before the module is removed.
> 
> flush_workqueue is unnecessary since destroy_workqueue() itself calls
> drain_workqueue() which flushes repeatedly till the workqueue becomes empty.
> 
> Hence flush_workqueue has been removed.

create_workqueue(NAME) maps to alloc_workqueue(NAME, WQ_MEM_RECLAIM, 1),
so the change is effectively dropping WQ_MEM_RECLAIM and changing
concurrency value from 1 to WQ_DFL_ACTIVE.  It'd be nice to explain
why these changes are safe and I think they're. It just needs
explanations.

> Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>

Other than that, Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

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[PATCH] gpu: drm: amd: amdkfd: Remove create_workqueue() Bhaktipriya Shridhar <bhaktipriya96@gmail.com> - 2016-05-26 20:50 +0200
  Re: [PATCH] gpu: drm: amd: amdkfd: Remove create_workqueue() Tejun Heo <tj@kernel.org> - 2016-05-26 21:00 +0200

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