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workqueue: simplify wq_update_unbound_numa() 

wq_update_unbound_numa() is known be called with wq_pool_mutex held.

But wq_update_unbound_numa() requests wq->mutex before reading
wq->unbound_attrs, wq->numa_pwq_tbl[] and wq->dfl_pwq.  But these fields
were changed to be allowed being read with wq_pool_mutex held.  So we
simply remove the mutex_lock(&wq->mutex).

Without the dependence on the the mutex_lock(&wq->mutex), the test
of wq->unbound_attrs->no_numa can also be moved upward.

The old code need a long comment to describe the stableness of
@wq->unbound_attrs which is also guaranteed by wq_pool_mutex now,
so we don't need this such comment.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2015-05-12 20:32:30 +08:00 committed by Tejun Heo
parent 5b95e1af8d
commit f7142ed483
1 changed files with 5 additions and 15 deletions
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20
kernel/workqueue.c
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@ -3708,7 +3708,8 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
lockdep_assert_held(&wq_pool_mutex);
if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) ||
wq->unbound_attrs->no_numa)
return;
/*
@ -3719,10 +3720,6 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
target_attrs = wq_update_unbound_numa_attrs_buf;
cpumask = target_attrs->cpumask;
mutex_lock(&wq->mutex);
if (wq->unbound_attrs->no_numa)
goto out_unlock;
copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
pwq = unbound_pwq_by_node(wq, node);
@ -3734,33 +3731,26 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
*/
if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
goto out_unlock;
return;
} else {
goto use_dfl_pwq;
}
mutex_unlock(&wq->mutex);
/* create a new pwq */
pwq = alloc_unbound_pwq(wq, target_attrs);
if (!pwq) {
pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
wq->name);
mutex_lock(&wq->mutex);
goto use_dfl_pwq;
}
/*
* Install the new pwq. As this function is called only from CPU
* hotplug callbacks and applying a new attrs is wrapped with
* get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
* inbetween.
*/
/* Install the new pwq. */
mutex_lock(&wq->mutex);
old_pwq = numa_pwq_tbl_install(wq, node, pwq);
goto out_unlock;
use_dfl_pwq:
mutex_lock(&wq->mutex);
spin_lock_irq(&wq->dfl_pwq->pool->lock);
get_pwq(wq->dfl_pwq);
spin_unlock_irq(&wq->dfl_pwq->pool->lock);