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Commit 420c0ddb authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: remove workqueue_struct->pool_wq.single 



workqueue->pool_wq union is used to point either to percpu pwqs
(pool_workqueues) or single unbound pwq.  As the first pwq can be
accessed via workqueue->pwqs list, there's no reason for the single
pointer anymore.

Use list_first_entry(workqueue->pwqs) to access the unbound pwq and
drop workqueue->pool_wq.single pointer and the pool_wq union.  It
simplifies the code and eases implementing multiple unbound pools w/
custom attributes.

This patch doesn't introduce any visible behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
parent d84ff051

kernel/workqueue.c

+12 −14
Original line number Diff line number Diff line
@@ -188,11 +188,7 @@ struct wq_flusher { 
 */

struct workqueue_struct {

	unsigned int		flags;		/* W: WQ_* flags */

	union {

		struct pool_workqueue __percpu		*pcpu;

		struct pool_workqueue			*single;

		unsigned long				v;

	} pool_wq;				/* I: pwq's */

	struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwq's */

	struct list_head	pwqs;		/* I: all pwqs of this wq */

	struct list_head	list;		/* W: list of all workqueues */
@@ -471,9 +467,11 @@ static struct pool_workqueue *get_pwq(int cpu, struct workqueue_struct *wq) 
{

	if (!(wq->flags & WQ_UNBOUND)) {

		if (likely(cpu < nr_cpu_ids))

			return per_cpu_ptr(wq->pool_wq.pcpu, cpu);

	} else if (likely(cpu == WORK_CPU_UNBOUND))

		return wq->pool_wq.single;

			return per_cpu_ptr(wq->cpu_pwqs, cpu);

	} else if (likely(cpu == WORK_CPU_UNBOUND)) {

		return list_first_entry(&wq->pwqs, struct pool_workqueue,

					pwqs_node);

	}

	return NULL;

}
@@ -3085,8 +3083,8 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) 
	int cpu;



	if (!(wq->flags & WQ_UNBOUND)) {

		wq->pool_wq.pcpu = alloc_percpu(struct pool_workqueue);

		if (!wq->pool_wq.pcpu)

		wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);

		if (!wq->cpu_pwqs)

			return -ENOMEM;



		for_each_possible_cpu(cpu) {
@@ -3102,7 +3100,6 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) 
		if (!pwq)

			return -ENOMEM;



		wq->pool_wq.single = pwq;

		pwq->pool = get_std_worker_pool(WORK_CPU_UNBOUND, highpri);

		list_add_tail(&pwq->pwqs_node, &wq->pwqs);

	}
@@ -3113,9 +3110,10 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) 
static void free_pwqs(struct workqueue_struct *wq)

{

	if (!(wq->flags & WQ_UNBOUND))

		free_percpu(wq->pool_wq.pcpu);

	else

		kmem_cache_free(pwq_cache, wq->pool_wq.single);

		free_percpu(wq->cpu_pwqs);

	else if (!list_empty(&wq->pwqs))

		kmem_cache_free(pwq_cache, list_first_entry(&wq->pwqs,

					struct pool_workqueue, pwqs_node));

}



static int wq_clamp_max_active(int max_active, unsigned int flags,