Re: [PATCH 06/12] workqueue: destroy_worker() can only destory idle worker not just created worker

[Tejun Heo <tj@kernel.org>]

On Thu, Sep 27, 2012 at 01:20:37AM +0800, Lai Jiangshan wrote:
> After we reimpletment hotplug code, we will not destroy just newly
> created worker, all created worker will enter idle soon.
> And destroy_worker() is not used to destroy just newly created worker,
> it always destory idle worker, so we need to fix destroy_worker()
> and update the comments.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
>  kernel/workqueue.c |   14 +++++++-------
>  1 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 6c339bf..fe3b1d3 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1756,8 +1756,7 @@ static struct worker *alloc_worker(void)
>   * @pool: pool the new worker will belong to
>   *
>   * Create a new worker which is bound to @pool.  The returned worker
> - * can be started by calling start_worker() or destroyed using
> - * destroy_worker().
> + * can be started by calling start_worker();
>   *
>   * CONTEXT:
>   * Might sleep.  Does GFP_KERNEL allocations.
> @@ -1847,7 +1846,7 @@ static void start_worker(struct worker *worker)
>  }
>  
>  /**
> - * destroy_worker - destroy a workqueue worker
> + * destroy_worker - destroy a idle workqueue worker
>   * @worker: worker to be destroyed
>   *
>   * Destroy @worker and adjust @gcwq stats accordingly.
> @@ -1864,11 +1863,12 @@ static void destroy_worker(struct worker *worker)
>  	/* sanity check frenzy */
>  	BUG_ON(worker->current_work);
>  	BUG_ON(!list_empty(&worker->scheduled));
> +	BUG_ON(!(worker->flags & WORKER_STARTED));
> +	BUG_ON(!(worker->flags & WORKER_IDLE));
> +	BUG_ON(list_empty(&worker->entry));

Let's go for WARN_ON() at least for the new ones.  Or let's convert
all BUG()s to WARN_ON[_ONCE]() beforehand.

Thanks.

-- 
tejun