Re: [PATCH 2/3] workqueue: extend wq_pool_mutex to also protect pwq-installation

From: Tejun Heo
Date: Mon Oct 27 2014 - 09:20:57 EST


Hello, Lai.

On Wed, Oct 08, 2014 at 11:53:32AM +0800, Lai Jiangshan wrote:
> Athough pwq-installation without wq_pool_mutex held is not bug,
> but it is not good design, it is better to make the pwq-allocation and installation
> are in the (same) wq_pool_mutex.

WHY? Why is that not a good design and why is extending the locking a
better thing to do? Can you elaborate the reasoning here?

> And since the pwq-allocation and installation are in the same wq_pool_mutex,
> get_online_cpus() will not be needed for this reason, and it will be remove
> in later patch.

So, if this enables further cleanup, it's fine, but please just stick
to those reasons. You do this a lot. You wanna do A because of B but
the changelog often doesn't mention that at all and just goes "This is
bad so change this to be better" without any proper reasoning. If you
want to do A to achieve B later, just say so.

Thanks.

--
tejun
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