Hello,
On Thu, May 22, 2014 at 07:01:16PM +0800, Lai Jiangshan wrote:
> While freezing takes place globally, its execution is per-workqueue;
> however, the current implementation makes use of the per-worker_pool
> POOL_FREEZING flag. While it's not broken, the flag makes the code
> more confusing and complicates freeze_workqueues_begin() and
> thaw_workqueues() by requiring them to walk through all pools.
>
> So we remove the POOL_FREEZING and use workqueue_freezing instead.
Misses the part which explains how the middle step is unnecessary. I
used the following text instead.
workqueue: remove the confusing POOL_FREEZING
Currently, the global freezing state is propagated to worker_pools via
POOL_FREEZING and then to each workqueue; however, the middle step -
propagation through worker_pools - can be skipped as long as one or
more max_active adjustments happens for each workqueue after the
update to the global state is visible. The global workqueue freezing
state and the max_active adjustments during workqueue creation and
[un]freezing are serialized with wq_pool_mutex, so it's trivial to
guarantee that max_actives stay in sync with global freezing state.
POOL_FREEZING is unnecessary and makes the code more confusing and
complicates freeze_workqueues_begin() and thaw_workqueues() by
requiring them to walk through all pools.
Remove POOL_FREEZING and use workqueue_freezing directly instead.
Applied to wq/for-3.16.
Thanks.
--
tejun
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