[PATCH 4/6] workqueue: protect wq->pwqs and iteration with wq->mutex

From: Lai Jiangshan We're expanding wq->mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. init_and_link_pwq() and pwq_unbound_release_workfn() already grab wq->mutex when adding or removing a

[PATCH 4/6] workqueue: protect wq-pwqs and iteration with wq-mutex

From: Lai Jiangshan la...@cn.fujitsu.com We're expanding wq-mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. init_and_link_pwq() and pwq_unbound_release_workfn() already grab wq-mutex when