linux-kernel - Re: [PATCH 03/10] workqueue: async worker destruction

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Date:	Mon, 5 May 2014 10:31:28 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/10] workqueue: async worker destruction

On Sun, Apr 27, 2014 at 12:08:58PM +0800, Lai Jiangshan wrote:
> worker destruction includes these parts of code:
> 	adjust pool's stats
> 	remove the worker from idle list
> 	unbind the worker from the pool
> 	kthread_stop() to wait for the worker's task exit
> 	free the worker struct
> 
> We can find out that there is no essential thing to do after
> kthread_stop(). Which means destroy_worker() doesn't need
> to wait for the worker's task exit. So we can remove kthread_stop()
> and free the worker struct in the worker exiting path.
> 
> But put_unbound_pool() still needs to sync the all the workers'
> destruction before to destroy the pool. Otherwise the workers
> may access to the invalid pool when they are exiting.
> 
> So we also move the code of "unbind the worker" to the exiting
> path and let put_unbound_pool() to sync with this code via
> a wait_queue_head_t workers_unbound.
> 
> The code of "unbind the worker" is wrapped in a function "worker_unbind_pool()"
> 
> Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
> ---
>  kernel/workqueue.c |   44 ++++++++++++++++++++++++++++----------------
>  1 files changed, 28 insertions(+), 16 deletions(-)

Is this any simpler?  Does this enable larger simplification down the
road?

Thanks.

-- 
tejun
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