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Commit b1f4ec17 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

workqueue: introduce cpu_singlethread_map 



The code like

	if (is_single_threaded(wq))
		do_something(singlethread_cpu);
	else {
		for_each_cpu_mask(cpu, cpu_populated_map)
			do_something(cpu);
	}

looks very annoying. We can add "static cpumask_t cpu_singlethread_map" and
simplify the code. Lessens .text a bit, and imho makes the code more readable.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dfb4b82e

kernel/workqueue.c

+25 −30
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ static DEFINE_MUTEX(workqueue_mutex); 
static LIST_HEAD(workqueues);



static int singlethread_cpu __read_mostly;

static cpumask_t cpu_singlethread_map __read_mostly;

/* optimization, we could use cpu_possible_map */

static cpumask_t cpu_populated_map __read_mostly;
@@ -78,6 +79,12 @@ static inline int is_single_threaded(struct workqueue_struct *wq) 
	return list_empty(&wq->list);

}



static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)

{

	return is_single_threaded(wq)

		? &cpu_singlethread_map : &cpu_populated_map;

}



/*

 * Set the workqueue on which a work item is to be run

 * - Must *only* be called if the pending flag is set
@@ -393,17 +400,13 @@ static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) 
 */

void fastcall flush_workqueue(struct workqueue_struct *wq)

{

	might_sleep();

	const cpumask_t *cpu_map = wq_cpu_map(wq);

	int cpu



	if (is_single_threaded(wq))

		flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));

	else {

		int cpu;



		for_each_cpu_mask(cpu, cpu_populated_map)

	might_sleep();

	for_each_cpu_mask(cpu, *cpu_map)

		flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));

}

}

EXPORT_SYMBOL_GPL(flush_workqueue);



static void wait_on_work(struct cpu_workqueue_struct *cwq,
@@ -439,7 +442,9 @@ static void wait_on_work(struct cpu_workqueue_struct *cwq, 
 */

void flush_work(struct workqueue_struct *wq, struct work_struct *work)

{

	const cpumask_t *cpu_map = wq_cpu_map(wq);

	struct cpu_workqueue_struct *cwq;

	int cpu;



	might_sleep();
@@ -457,15 +462,9 @@ void flush_work(struct workqueue_struct *wq, struct work_struct *work) 
	work_release(work);

	spin_unlock_irq(&cwq->lock);



	if (is_single_threaded(wq))

		wait_on_work(per_cpu_ptr(wq->cpu_wq, singlethread_cpu), work);

	else {

		int cpu;



		for_each_cpu_mask(cpu, cpu_populated_map)

	for_each_cpu_mask(cpu, *cpu_map)

		wait_on_work(per_cpu_ptr(wq->cpu_wq, cpu), work);

}

}

EXPORT_SYMBOL_GPL(flush_work);
@@ -757,23 +756,18 @@ static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) 
 */

void destroy_workqueue(struct workqueue_struct *wq)

{

	const cpumask_t *cpu_map = wq_cpu_map(wq);

	struct cpu_workqueue_struct *cwq;



	if (is_single_threaded(wq)) {

		cwq = per_cpu_ptr(wq->cpu_wq, singlethread_cpu);

		cleanup_workqueue_thread(cwq, singlethread_cpu);

	} else {

	int cpu;



	mutex_lock(&workqueue_mutex);

	list_del(&wq->list);

	mutex_unlock(&workqueue_mutex);



		for_each_cpu_mask(cpu, cpu_populated_map) {

	for_each_cpu_mask(cpu, *cpu_map) {

		cwq = per_cpu_ptr(wq->cpu_wq, cpu);

		cleanup_workqueue_thread(cwq, cpu);

	}

	}



	free_percpu(wq->cpu_wq);

	kfree(wq);
@@ -831,6 +825,7 @@ void init_workqueues(void) 
{

	cpu_populated_map = cpu_online_map;

	singlethread_cpu = first_cpu(cpu_possible_map);

	cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);

	hotcpu_notifier(workqueue_cpu_callback, 0);

	keventd_wq = create_workqueue("events");

	BUG_ON(!keventd_wq);