Messages in this thread | | | Date | Mon, 11 May 2015 08:23:42 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH 1/5] workqueue: wq_pool_mutex protects the attrs-installation |
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On Mon, May 11, 2015 at 05:35:48PM +0800, Lai Jiangshan wrote: > @@ -127,6 +127,12 @@ enum { > * > * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. > * > + * PW: wq_pool_mutex and wq->mutex protected for writes. Any one of them > + * protected for reads.
Either for reads.
> + * > + * PWR: wq_pool_mutex and wq->mutex protected for writes. Any one of them > + * or sched-RCU for reads.
Ditto.
> + * > * WQ: wq->mutex protected. > * > * WR: wq->mutex protected for writes. Sched-RCU protected for reads. ... > @@ -553,7 +565,7 @@ static int worker_pool_assign_id(struct worker_pool *pool) > * @wq: the target workqueue > * @node: the node ID > * > - * This must be called either with pwq_lock held or sched RCU read locked. > + * This must be called either with wq_pool_mutex held or sched RCU read locked.
The comment was outdated before too but the updated one isn't correct either.
> * If the pwq needs to be used beyond the locking in effect, the caller is > * responsible for guaranteeing that the pwq stays online. > * > @@ -562,7 +574,7 @@ static int worker_pool_assign_id(struct worker_pool *pool) > static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, > int node) > { > - assert_rcu_or_wq_mutex(wq); > + assert_rcu_or_wq_mutex_or_pool_mutex(wq); > return rcu_dereference_raw(wq->numa_pwq_tbl[node]); > } > ... > @@ -3644,10 +3657,9 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, > * pwqs accordingly. > */ > get_online_cpus(); > - > mutex_lock(&wq_pool_mutex); > + > ctx = apply_wqattrs_prepare(wq, attrs); > - mutex_unlock(&wq_pool_mutex); > > /* the ctx has been prepared successfully, let's commit it */ > if (ctx) { > @@ -3655,10 +3667,11 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, > ret = 0; > } > > - put_online_cpus(); > - > apply_wqattrs_cleanup(ctx);
Why are we protecting cleanup?
> + mutex_unlock(&wq_pool_mutex); > + put_online_cpus(); > + > return ret; > } >
Thanks.
-- tejun
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