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Commit fa14ff4a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Convert to struct llist 



Use the generic llist primitives.

We had a private lockless list implementation in the scheduler in the wake-list
code, now that we have a generic llist implementation that provides all required
operations, switch to it.

This patch is not expected to change any behavior.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1315836353.26517.42.camel@twins


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 924f8f5a

include/linux/sched.h

+2 −1
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ struct sched_param { 
#include <linux/task_io_accounting.h>

#include <linux/latencytop.h>

#include <linux/cred.h>

#include <linux/llist.h>



#include <asm/processor.h>
@@ -1225,7 +1226,7 @@ struct task_struct { 
	unsigned int ptrace;



#ifdef CONFIG_SMP

	struct task_struct *wake_entry;

	struct llist_node wake_entry;

	int on_cpu;

#endif

	int on_rq;

kernel/sched.c

+10 −38
Original line number Diff line number Diff line
@@ -702,7 +702,7 @@ struct rq { 
#endif



#ifdef CONFIG_SMP

	struct task_struct *wake_list;

	struct llist_head wake_list;

#endif

};
@@ -2698,42 +2698,26 @@ static int ttwu_remote(struct task_struct *p, int wake_flags) 
}



#ifdef CONFIG_SMP

static void sched_ttwu_do_pending(struct task_struct *list)

static void sched_ttwu_pending(void)

{

	struct rq *rq = this_rq();

	struct llist_node *llist = llist_del_all(&rq->wake_list);

	struct task_struct *p;



	raw_spin_lock(&rq->lock);



	while (list) {

		struct task_struct *p = list;

		list = list->wake_entry;

	while (llist) {

		p = llist_entry(llist, struct task_struct, wake_entry);

		llist = llist_next(llist);

		ttwu_do_activate(rq, p, 0);

	}



	raw_spin_unlock(&rq->lock);

}



#ifdef CONFIG_HOTPLUG_CPU



static void sched_ttwu_pending(void)

{

	struct rq *rq = this_rq();

	struct task_struct *list = xchg(&rq->wake_list, NULL);



	if (!list)

		return;



	sched_ttwu_do_pending(list);

}



#endif /* CONFIG_HOTPLUG_CPU */



void scheduler_ipi(void)

{

	struct rq *rq = this_rq();

	struct task_struct *list = xchg(&rq->wake_list, NULL);



	if (!list)

	if (llist_empty(&this_rq()->wake_list))

		return;



	/*
@@ -2750,25 +2734,13 @@ void scheduler_ipi(void) 
	 * somewhat pessimize the simple resched case.

	 */

	irq_enter();

	sched_ttwu_do_pending(list);

	sched_ttwu_pending();

	irq_exit();

}



static void ttwu_queue_remote(struct task_struct *p, int cpu)

{

	struct rq *rq = cpu_rq(cpu);

	struct task_struct *next = rq->wake_list;



	for (;;) {

		struct task_struct *old = next;



		p->wake_entry = next;

		next = cmpxchg(&rq->wake_list, old, p);

		if (next == old)

			break;

	}



	if (!next)

	if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))

		smp_send_reschedule(cpu);

}