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workqueue: introduce numa_pwq_tbl_install()

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Factor out pool_workqueue linking and installation into numa_pwq_tbl[]
from apply_workqueue_attrs() into numa_pwq_tbl_install().  link_pwq()
is made safe to call multiple times.  numa_pwq_tbl_install() links the
pwq, installs it into numa_pwq_tbl[] at the specified node and returns
the old entry.

@last_pwq is removed from link_pwq() as the return value of the new
function can be used instead.

This is to prepare for NUMA affinity support for unbound workqueues.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This commit is contained in:
Tejun Heo 2013-04-01 11:23:35 -07:00
commit 1befcf3073
1 changed files with 26 additions and 9 deletions
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35
kernel/workqueue.c
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@ -3639,24 +3639,26 @@ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
pwq->flush_color = -1;
pwq->refcnt = 1;
INIT_LIST_HEAD(&pwq->delayed_works);
INIT_LIST_HEAD(&pwq->pwqs_node);
INIT_LIST_HEAD(&pwq->mayday_node);
INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
}
/* sync @pwq with the current state of its associated wq and link it */
static void link_pwq(struct pool_workqueue *pwq,
struct pool_workqueue **p_last_pwq)
static void link_pwq(struct pool_workqueue *pwq)
{
struct workqueue_struct *wq = pwq->wq;
lockdep_assert_held(&wq->mutex);
/* may be called multiple times, ignore if already linked */
if (!list_empty(&pwq->pwqs_node))
return;
/*
* Set the matching work_color. This is synchronized with
* wq->mutex to avoid confusing flush_workqueue().
*/
if (p_last_pwq)
*p_last_pwq = first_pwq(wq);
pwq->work_color = wq->work_color;
/* sync max_active to the current setting */
@ -3689,6 +3691,23 @@ static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
return pwq;
}
/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
int node,
struct pool_workqueue *pwq)
{
struct pool_workqueue *old_pwq;
lockdep_assert_held(&wq->mutex);
/* link_pwq() can handle duplicate calls */
link_pwq(pwq);
old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
return old_pwq;
}
/**
* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
* @wq: the target workqueue
@ -3707,7 +3726,7 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
const struct workqueue_attrs *attrs)
{
struct workqueue_attrs *new_attrs;
struct pool_workqueue *pwq, *last_pwq;
struct pool_workqueue *pwq, *last_pwq = NULL;
int node, ret;
/* only unbound workqueues can change attributes */
@ -3734,11 +3753,9 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
mutex_lock(&wq->mutex);
link_pwq(pwq, &last_pwq);
copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
for_each_node(node)
rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
last_pwq = numa_pwq_tbl_install(wq, node, pwq);
mutex_unlock(&wq->mutex);
@ -3778,7 +3795,7 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq)
init_pwq(pwq, wq, &cpu_pools[highpri]);
mutex_lock(&wq->mutex);
link_pwq(pwq, NULL);
link_pwq(pwq);
mutex_unlock(&wq->mutex);
}
return 0;