arch/powerpc/platforms/cell/spufs/sched.c - kernel/msm-4.9 - Gitiles

 /* sched.c - SPU scheduler.
  *
  * Copyright (C) IBM 2005
  * Author: Mark Nutter <mnutter@us.ibm.com>
  *
  * 2006-03-31	NUMA domains added.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

 #undef DEBUG

 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/completion.h>
 #include <linux/vmalloc.h>
 #include <linux/smp.h>
 #include <linux/smp_lock.h>
 #include <linux/stddef.h>
 #include <linux/unistd.h>
 #include <linux/numa.h>
 #include <linux/mutex.h>
 #include <linux/notifier.h>

 #include <asm/io.h>
 #include <asm/mmu_context.h>
 #include <asm/spu.h>
 #include <asm/spu_csa.h>
 #include <asm/spu_priv1.h>
 #include "spufs.h"

 #define SPU_TIMESLICE	(HZ)

 struct spu_prio_array {
 	DECLARE_BITMAP(bitmap, MAX_PRIO);
 	struct list_head runq[MAX_PRIO];
 	spinlock_t runq_lock;
 	struct list_head active_list[MAX_NUMNODES];
 	struct mutex active_mutex[MAX_NUMNODES];
 };

 static struct spu_prio_array *spu_prio;
 static struct workqueue_struct *spu_sched_wq;

 static inline int node_allowed(int node)
 {
 	cpumask_t mask;

 	if (!nr_cpus_node(node))
 		return 0;
 	mask = node_to_cpumask(node);
 	if (!cpus_intersects(mask, current->cpus_allowed))
 		return 0;
 	return 1;
 }

 void spu_start_tick(struct spu_context *ctx)
 {
 	if (ctx->policy == SCHED_RR)
 		queue_delayed_work(spu_sched_wq, &ctx->sched_work, SPU_TIMESLICE);
 }

 void spu_stop_tick(struct spu_context *ctx)
 {
 	if (ctx->policy == SCHED_RR)
 		cancel_delayed_work(&ctx->sched_work);
 }

 void spu_sched_tick(struct work_struct *work)
 {
 	struct spu_context *ctx =
 		container_of(work, struct spu_context, sched_work.work);
 	struct spu *spu;
 	int rearm = 1;

 	mutex_lock(&ctx->state_mutex);
 	spu = ctx->spu;
 	if (spu) {
 		int best = sched_find_first_bit(spu_prio->bitmap);
 		if (best <= ctx->prio) {
 			spu_deactivate(ctx);
 			rearm = 0;
 		}
 	}
 	mutex_unlock(&ctx->state_mutex);

 	if (rearm)
 		spu_start_tick(ctx);
 }

 /**
  * spu_add_to_active_list - add spu to active list
  * @spu:	spu to add to the active list
  */
 static void spu_add_to_active_list(struct spu *spu)
 {
 	mutex_lock(&spu_prio->active_mutex[spu->node]);
 	list_add_tail(&spu->list, &spu_prio->active_list[spu->node]);
 	mutex_unlock(&spu_prio->active_mutex[spu->node]);
 }

 /**
  * spu_remove_from_active_list - remove spu from active list
  * @spu:       spu to remove from the active list
  */
 static void spu_remove_from_active_list(struct spu *spu)
 {
 	int node = spu->node;

 	mutex_lock(&spu_prio->active_mutex[node]);
 	list_del_init(&spu->list);
 	mutex_unlock(&spu_prio->active_mutex[node]);
 }

 static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);

 static void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
 {
 	blocking_notifier_call_chain(&spu_switch_notifier,
 			    ctx ? ctx->object_id : 0, spu);
 }

 int spu_switch_event_register(struct notifier_block * n)
 {
 	return blocking_notifier_chain_register(&spu_switch_notifier, n);
 }

 int spu_switch_event_unregister(struct notifier_block * n)
 {
 	return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
 }

 /**
  * spu_bind_context - bind spu context to physical spu
  * @spu:	physical spu to bind to
  * @ctx:	context to bind
  */
 static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
 {
 	pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
 		 spu->number, spu->node);
 	spu->ctx = ctx;
 	spu->flags = 0;
 	ctx->spu = spu;
 	ctx->ops = &spu_hw_ops;
 	spu->pid = current->pid;
 	spu_associate_mm(spu, ctx->owner);
 	spu->ibox_callback = spufs_ibox_callback;
 	spu->wbox_callback = spufs_wbox_callback;
 	spu->stop_callback = spufs_stop_callback;
 	spu->mfc_callback = spufs_mfc_callback;
 	spu->dma_callback = spufs_dma_callback;
 	mb();
 	spu_unmap_mappings(ctx);
 	spu_restore(&ctx->csa, spu);
 	spu->timestamp = jiffies;
 	spu_cpu_affinity_set(spu, raw_smp_processor_id());
 	spu_switch_notify(spu, ctx);
 	spu_add_to_active_list(spu);
 	ctx->state = SPU_STATE_RUNNABLE;
 }

 /**
  * spu_unbind_context - unbind spu context from physical spu
  * @spu:	physical spu to unbind from
  * @ctx:	context to unbind
  */
 static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
 {
 	pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
 		 spu->pid, spu->number, spu->node);

 	spu_remove_from_active_list(spu);
 	spu_switch_notify(spu, NULL);
 	spu_unmap_mappings(ctx);
 	spu_save(&ctx->csa, spu);
 	spu->timestamp = jiffies;
 	ctx->state = SPU_STATE_SAVED;
 	spu->ibox_callback = NULL;
 	spu->wbox_callback = NULL;
 	spu->stop_callback = NULL;
 	spu->mfc_callback = NULL;
 	spu->dma_callback = NULL;
 	spu_associate_mm(spu, NULL);
 	spu->pid = 0;
 	ctx->ops = &spu_backing_ops;
 	ctx->spu = NULL;
 	spu->flags = 0;
 	spu->ctx = NULL;
 }

 /**
  * spu_add_to_rq - add a context to the runqueue
  * @ctx:       context to add
  */
 static void spu_add_to_rq(struct spu_context *ctx)
 {
 	spin_lock(&spu_prio->runq_lock);
 	list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
 	set_bit(ctx->prio, spu_prio->bitmap);
 	spin_unlock(&spu_prio->runq_lock);
 }

 /**
  * spu_del_from_rq - remove a context from the runqueue
  * @ctx:       context to remove
  */
 static void spu_del_from_rq(struct spu_context *ctx)
 {
 	spin_lock(&spu_prio->runq_lock);
 	list_del_init(&ctx->rq);
 	if (list_empty(&spu_prio->runq[ctx->prio]))
 		clear_bit(ctx->prio, spu_prio->bitmap);
 	spin_unlock(&spu_prio->runq_lock);
 }

 /**
  * spu_grab_context - remove one context from the runqueue
  * @prio:      priority of the context to be removed
  *
  * This function removes one context from the runqueue for priority @prio.
  * If there is more than one context with the given priority the first
  * task on the runqueue will be taken.
  *
  * Returns the spu_context it just removed.
  *
  * Must be called with spu_prio->runq_lock held.
  */
 static struct spu_context *spu_grab_context(int prio)
 {
 	struct list_head *rq = &spu_prio->runq[prio];

 	if (list_empty(rq))
 		return NULL;
 	return list_entry(rq->next, struct spu_context, rq);
 }

 static void spu_prio_wait(struct spu_context *ctx)
 {
 	DEFINE_WAIT(wait);

 	prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
 	if (!signal_pending(current)) {
 		mutex_unlock(&ctx->state_mutex);
 		schedule();
 		mutex_lock(&ctx->state_mutex);
 	}
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&ctx->stop_wq, &wait);
 }

 /**
  * spu_reschedule - try to find a runnable context for a spu
  * @spu:       spu available
  *
  * This function is called whenever a spu becomes idle.  It looks for the
  * most suitable runnable spu context and schedules it for execution.
  */
 static void spu_reschedule(struct spu *spu)
 {
 	int best;

 	spu_free(spu);

 	spin_lock(&spu_prio->runq_lock);
 	best = sched_find_first_bit(spu_prio->bitmap);
 	if (best < MAX_PRIO) {
 		struct spu_context *ctx = spu_grab_context(best);
 		if (ctx)
 			wake_up(&ctx->stop_wq);
 	}
 	spin_unlock(&spu_prio->runq_lock);
 }

 static struct spu *spu_get_idle(struct spu_context *ctx)
 {
 	struct spu *spu = NULL;
 	int node = cpu_to_node(raw_smp_processor_id());
 	int n;

 	for (n = 0; n < MAX_NUMNODES; n++, node++) {
 		node = (node < MAX_NUMNODES) ? node : 0;
 		if (!node_allowed(node))
 			continue;
 		spu = spu_alloc_node(node);
 		if (spu)
 			break;
 	}
 	return spu;
 }

 /**
  * find_victim - find a lower priority context to preempt
  * @ctx:	canidate context for running
  *
  * Returns the freed physical spu to run the new context on.
  */
 static struct spu *find_victim(struct spu_context *ctx)
 {
 	struct spu_context *victim = NULL;
 	struct spu *spu;
 	int node, n;

 	/*
 	 * Look for a possible preemption candidate on the local node first.
 	 * If there is no candidate look at the other nodes.  This isn't
 	 * exactly fair, but so far the whole spu schedule tries to keep
 	 * a strong node affinity.  We might want to fine-tune this in
 	 * the future.
 	 */
  restart:
 	node = cpu_to_node(raw_smp_processor_id());
 	for (n = 0; n < MAX_NUMNODES; n++, node++) {
 		node = (node < MAX_NUMNODES) ? node : 0;
 		if (!node_allowed(node))
 			continue;

 		mutex_lock(&spu_prio->active_mutex[node]);
 		list_for_each_entry(spu, &spu_prio->active_list[node], list) {
 			struct spu_context *tmp = spu->ctx;

 			if (tmp->rt_priority < ctx->rt_priority &&
 			    (!victim || tmp->rt_priority < victim->rt_priority))
 				victim = spu->ctx;
 		}
 		mutex_unlock(&spu_prio->active_mutex[node]);

 		if (victim) {
 			/*
 			 * This nests ctx->state_mutex, but we always lock
 			 * higher priority contexts before lower priority
 			 * ones, so this is safe until we introduce
 			 * priority inheritance schemes.
 			 */
 			if (!mutex_trylock(&victim->state_mutex)) {
 				victim = NULL;
 				goto restart;
 			}

 			spu = victim->spu;
 			if (!spu) {
 				/*
 				 * This race can happen because we've dropped
 				 * the active list mutex.  No a problem, just
 				 * restart the search.
 				 */
 				mutex_unlock(&victim->state_mutex);
 				victim = NULL;
 				goto restart;
 			}
 			spu_unbind_context(spu, victim);
 			mutex_unlock(&victim->state_mutex);
 			return spu;
 		}
 	}

 	return NULL;
 }

 /**
  * spu_activate - find a free spu for a context and execute it
  * @ctx:	spu context to schedule
  * @flags:	flags (currently ignored)
  *
  * Tries to find a free spu to run @ctx.  If no free spu is availble
  * add the context to the runqueue so it gets woken up once an spu
  * is available.
  */
 int spu_activate(struct spu_context *ctx, unsigned long flags)
 {

 	if (ctx->spu)
 		return 0;

 	do {
 		struct spu *spu;

 		spu = spu_get_idle(ctx);
 		/*
 		 * If this is a realtime thread we try to get it running by
 		 * preempting a lower priority thread.
 		 */
 		if (!spu && ctx->rt_priority)
 			spu = find_victim(ctx);
 		if (spu) {
 			spu_bind_context(spu, ctx);
 			return 0;
 		}

 		spu_add_to_rq(ctx);
 		spu_prio_wait(ctx);
 		spu_del_from_rq(ctx);
 	} while (!signal_pending(current));

 	return -ERESTARTSYS;
 }

 /**
  * spu_deactivate - unbind a context from it's physical spu
  * @ctx:	spu context to unbind
  *
  * Unbind @ctx from the physical spu it is running on and schedule
  * the highest priority context to run on the freed physical spu.
  */
 void spu_deactivate(struct spu_context *ctx)
 {
 	struct spu *spu = ctx->spu;

 	if (spu) {
 		spu_unbind_context(spu, ctx);
 		spu_reschedule(spu);
 	}
 }

 /**
  * spu_yield -  yield a physical spu if others are waiting
  * @ctx:	spu context to yield
  *
  * Check if there is a higher priority context waiting and if yes
  * unbind @ctx from the physical spu and schedule the highest
  * priority context to run on the freed physical spu instead.
  */
 void spu_yield(struct spu_context *ctx)
 {
 	struct spu *spu;
 	int need_yield = 0;

 	if (mutex_trylock(&ctx->state_mutex)) {
 		if ((spu = ctx->spu) != NULL) {
 			int best = sched_find_first_bit(spu_prio->bitmap);
 			if (best < MAX_PRIO) {
 				pr_debug("%s: yielding SPU %d NODE %d\n",
 					 __FUNCTION__, spu->number, spu->node);
 				spu_deactivate(ctx);
 				need_yield = 1;
 			}
 		}
 		mutex_unlock(&ctx->state_mutex);
 	}
 	if (unlikely(need_yield))
 		yield();
 }

 int __init spu_sched_init(void)
 {
 	int i;

 	spu_sched_wq = create_singlethread_workqueue("spusched");
 	if (!spu_sched_wq)
 		return 1;

 	spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
 	if (!spu_prio) {
 		printk(KERN_WARNING "%s: Unable to allocate priority queue.\n",
 		       __FUNCTION__);
 		       destroy_workqueue(spu_sched_wq);
 		return 1;
 	}
 	for (i = 0; i < MAX_PRIO; i++) {
 		INIT_LIST_HEAD(&spu_prio->runq[i]);
 		__clear_bit(i, spu_prio->bitmap);
 	}
 	__set_bit(MAX_PRIO, spu_prio->bitmap);
 	for (i = 0; i < MAX_NUMNODES; i++) {
 		mutex_init(&spu_prio->active_mutex[i]);
 		INIT_LIST_HEAD(&spu_prio->active_list[i]);
 	}
 	spin_lock_init(&spu_prio->runq_lock);
 	return 0;
 }

 void __exit spu_sched_exit(void)
 {
 	struct spu *spu, *tmp;
 	int node;

 	for (node = 0; node < MAX_NUMNODES; node++) {
 		mutex_lock(&spu_prio->active_mutex[node]);
 		list_for_each_entry_safe(spu, tmp, &spu_prio->active_list[node],
 					 list) {
 			list_del_init(&spu->list);
 			spu_free(spu);
 		}
 		mutex_unlock(&spu_prio->active_mutex[node]);
 	}
 	kfree(spu_prio);
 	destroy_workqueue(spu_sched_wq);
 }
	/* sched.c - SPU scheduler.
	*
	* Copyright (C) IBM 2005
	* Author: Mark Nutter <mnutter@us.ibm.com>
	*
	* 2006-03-31 NUMA domains added.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2, or (at your option)
	* any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	#undef DEBUG

	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/sched.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/completion.h>
	#include <linux/vmalloc.h>
	#include <linux/smp.h>
	#include <linux/smp_lock.h>
	#include <linux/stddef.h>
	#include <linux/unistd.h>
	#include <linux/numa.h>
	#include <linux/mutex.h>
	#include <linux/notifier.h>

	#include <asm/io.h>
	#include <asm/mmu_context.h>
	#include <asm/spu.h>
	#include <asm/spu_csa.h>
	#include <asm/spu_priv1.h>
	#include "spufs.h"

	#define SPU_TIMESLICE (HZ)

	struct spu_prio_array {
	DECLARE_BITMAP(bitmap, MAX_PRIO);
	struct list_head runq[MAX_PRIO];
	spinlock_t runq_lock;
	struct list_head active_list[MAX_NUMNODES];
	struct mutex active_mutex[MAX_NUMNODES];
	};

	static struct spu_prio_array *spu_prio;
	static struct workqueue_struct *spu_sched_wq;

	static inline int node_allowed(int node)
	{
	cpumask_t mask;

	if (!nr_cpus_node(node))
	return 0;
	mask = node_to_cpumask(node);
	if (!cpus_intersects(mask, current->cpus_allowed))
	return 0;
	return 1;
	}

	void spu_start_tick(struct spu_context *ctx)
	{
	if (ctx->policy == SCHED_RR)
	queue_delayed_work(spu_sched_wq, &ctx->sched_work, SPU_TIMESLICE);
	}

	void spu_stop_tick(struct spu_context *ctx)
	{
	if (ctx->policy == SCHED_RR)
	cancel_delayed_work(&ctx->sched_work);
	}

	void spu_sched_tick(struct work_struct *work)
	{
	struct spu_context *ctx =
	container_of(work, struct spu_context, sched_work.work);
	struct spu *spu;
	int rearm = 1;

	mutex_lock(&ctx->state_mutex);
	spu = ctx->spu;
	if (spu) {
	int best = sched_find_first_bit(spu_prio->bitmap);
	if (best <= ctx->prio) {
	spu_deactivate(ctx);
	rearm = 0;
	}
	}
	mutex_unlock(&ctx->state_mutex);

	if (rearm)
	spu_start_tick(ctx);
	}

	/**
	* spu_add_to_active_list - add spu to active list
	* @spu: spu to add to the active list
	*/
	static void spu_add_to_active_list(struct spu *spu)
	{
	mutex_lock(&spu_prio->active_mutex[spu->node]);
	list_add_tail(&spu->list, &spu_prio->active_list[spu->node]);
	mutex_unlock(&spu_prio->active_mutex[spu->node]);
	}

	/**
	* spu_remove_from_active_list - remove spu from active list
	* @spu: spu to remove from the active list
	*/
	static void spu_remove_from_active_list(struct spu *spu)
	{
	int node = spu->node;

	mutex_lock(&spu_prio->active_mutex[node]);
	list_del_init(&spu->list);
	mutex_unlock(&spu_prio->active_mutex[node]);
	}

	static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);

	static void spu_switch_notify(struct spu spu, struct spu_context ctx)
	{
	blocking_notifier_call_chain(&spu_switch_notifier,
	ctx ? ctx->object_id : 0, spu);
	}

	int spu_switch_event_register(struct notifier_block * n)
	{
	return blocking_notifier_chain_register(&spu_switch_notifier, n);
	}

	int spu_switch_event_unregister(struct notifier_block * n)
	{
	return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
	}

	/**
	* spu_bind_context - bind spu context to physical spu
	* @spu: physical spu to bind to
	* @ctx: context to bind
	*/
	static void spu_bind_context(struct spu spu, struct spu_context ctx)
	{
	pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
	spu->number, spu->node);
	spu->ctx = ctx;
	spu->flags = 0;
	ctx->spu = spu;
	ctx->ops = &spu_hw_ops;
	spu->pid = current->pid;
	spu_associate_mm(spu, ctx->owner);
	spu->ibox_callback = spufs_ibox_callback;
	spu->wbox_callback = spufs_wbox_callback;
	spu->stop_callback = spufs_stop_callback;
	spu->mfc_callback = spufs_mfc_callback;
	spu->dma_callback = spufs_dma_callback;
	mb();
	spu_unmap_mappings(ctx);
	spu_restore(&ctx->csa, spu);
	spu->timestamp = jiffies;
	spu_cpu_affinity_set(spu, raw_smp_processor_id());
	spu_switch_notify(spu, ctx);
	spu_add_to_active_list(spu);
	ctx->state = SPU_STATE_RUNNABLE;
	}

	/**
	* spu_unbind_context - unbind spu context from physical spu
	* @spu: physical spu to unbind from
	* @ctx: context to unbind
	*/
	static void spu_unbind_context(struct spu spu, struct spu_context ctx)
	{
	pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
	spu->pid, spu->number, spu->node);

	spu_remove_from_active_list(spu);
	spu_switch_notify(spu, NULL);
	spu_unmap_mappings(ctx);
	spu_save(&ctx->csa, spu);
	spu->timestamp = jiffies;
	ctx->state = SPU_STATE_SAVED;
	spu->ibox_callback = NULL;
	spu->wbox_callback = NULL;
	spu->stop_callback = NULL;
	spu->mfc_callback = NULL;
	spu->dma_callback = NULL;
	spu_associate_mm(spu, NULL);
	spu->pid = 0;
	ctx->ops = &spu_backing_ops;
	ctx->spu = NULL;
	spu->flags = 0;
	spu->ctx = NULL;
	}

	/**
	* spu_add_to_rq - add a context to the runqueue
	* @ctx: context to add
	*/
	static void spu_add_to_rq(struct spu_context *ctx)
	{
	spin_lock(&spu_prio->runq_lock);
	list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
	set_bit(ctx->prio, spu_prio->bitmap);
	spin_unlock(&spu_prio->runq_lock);
	}

	/**
	* spu_del_from_rq - remove a context from the runqueue
	* @ctx: context to remove
	*/
	static void spu_del_from_rq(struct spu_context *ctx)
	{
	spin_lock(&spu_prio->runq_lock);
	list_del_init(&ctx->rq);
	if (list_empty(&spu_prio->runq[ctx->prio]))
	clear_bit(ctx->prio, spu_prio->bitmap);
	spin_unlock(&spu_prio->runq_lock);
	}

	/**
	* spu_grab_context - remove one context from the runqueue
	* @prio: priority of the context to be removed
	*
	* This function removes one context from the runqueue for priority @prio.
	* If there is more than one context with the given priority the first
	* task on the runqueue will be taken.
	*
	* Returns the spu_context it just removed.
	*
	* Must be called with spu_prio->runq_lock held.
	*/
	static struct spu_context *spu_grab_context(int prio)
	{
	struct list_head *rq = &spu_prio->runq[prio];

	if (list_empty(rq))
	return NULL;
	return list_entry(rq->next, struct spu_context, rq);
	}

	static void spu_prio_wait(struct spu_context *ctx)
	{
	DEFINE_WAIT(wait);

	prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
	if (!signal_pending(current)) {
	mutex_unlock(&ctx->state_mutex);
	schedule();
	mutex_lock(&ctx->state_mutex);
	}
	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&ctx->stop_wq, &wait);
	}

	/**
	* spu_reschedule - try to find a runnable context for a spu
	* @spu: spu available
	*
	* This function is called whenever a spu becomes idle. It looks for the
	* most suitable runnable spu context and schedules it for execution.
	*/
	static void spu_reschedule(struct spu *spu)
	{
	int best;

	spu_free(spu);

	spin_lock(&spu_prio->runq_lock);
	best = sched_find_first_bit(spu_prio->bitmap);
	if (best < MAX_PRIO) {
	struct spu_context *ctx = spu_grab_context(best);
	if (ctx)
	wake_up(&ctx->stop_wq);
	}
	spin_unlock(&spu_prio->runq_lock);
	}

	static struct spu spu_get_idle(struct spu_context ctx)
	{
	struct spu *spu = NULL;
	int node = cpu_to_node(raw_smp_processor_id());
	int n;

	for (n = 0; n < MAX_NUMNODES; n++, node++) {
	node = (node < MAX_NUMNODES) ? node : 0;
	if (!node_allowed(node))
	continue;
	spu = spu_alloc_node(node);
	if (spu)
	break;
	}
	return spu;
	}

	/**
	* find_victim - find a lower priority context to preempt
	* @ctx: canidate context for running
	*
	* Returns the freed physical spu to run the new context on.
	*/
	static struct spu find_victim(struct spu_context ctx)
	{
	struct spu_context *victim = NULL;
	struct spu *spu;
	int node, n;

	/*
	* Look for a possible preemption candidate on the local node first.
	* If there is no candidate look at the other nodes. This isn't
	* exactly fair, but so far the whole spu schedule tries to keep
	* a strong node affinity. We might want to fine-tune this in
	* the future.
	*/
	restart:
	node = cpu_to_node(raw_smp_processor_id());
	for (n = 0; n < MAX_NUMNODES; n++, node++) {
	node = (node < MAX_NUMNODES) ? node : 0;
	if (!node_allowed(node))
	continue;

	mutex_lock(&spu_prio->active_mutex[node]);
	list_for_each_entry(spu, &spu_prio->active_list[node], list) {
	struct spu_context *tmp = spu->ctx;

	if (tmp->rt_priority < ctx->rt_priority &&
	(!victim \|\| tmp->rt_priority < victim->rt_priority))
	victim = spu->ctx;
	}
	mutex_unlock(&spu_prio->active_mutex[node]);

	if (victim) {
	/*
	* This nests ctx->state_mutex, but we always lock
	* higher priority contexts before lower priority
	* ones, so this is safe until we introduce
	* priority inheritance schemes.
	*/
	if (!mutex_trylock(&victim->state_mutex)) {
	victim = NULL;
	goto restart;
	}

	spu = victim->spu;
	if (!spu) {
	/*
	* This race can happen because we've dropped
	* the active list mutex. No a problem, just
	* restart the search.
	*/
	mutex_unlock(&victim->state_mutex);
	victim = NULL;
	goto restart;
	}
	spu_unbind_context(spu, victim);
	mutex_unlock(&victim->state_mutex);
	return spu;
	}
	}

	return NULL;
	}

	/**
	* spu_activate - find a free spu for a context and execute it
	* @ctx: spu context to schedule
	* @flags: flags (currently ignored)
	*
	* Tries to find a free spu to run @ctx. If no free spu is availble
	* add the context to the runqueue so it gets woken up once an spu
	* is available.
	*/
	int spu_activate(struct spu_context *ctx, unsigned long flags)
	{

	if (ctx->spu)
	return 0;

	do {
	struct spu *spu;

	spu = spu_get_idle(ctx);
	/*
	* If this is a realtime thread we try to get it running by
	* preempting a lower priority thread.
	*/
	if (!spu && ctx->rt_priority)
	spu = find_victim(ctx);
	if (spu) {
	spu_bind_context(spu, ctx);
	return 0;
	}

	spu_add_to_rq(ctx);
	spu_prio_wait(ctx);
	spu_del_from_rq(ctx);
	} while (!signal_pending(current));

	return -ERESTARTSYS;
	}

	/**
	* spu_deactivate - unbind a context from it's physical spu
	* @ctx: spu context to unbind
	*
	* Unbind @ctx from the physical spu it is running on and schedule
	* the highest priority context to run on the freed physical spu.
	*/
	void spu_deactivate(struct spu_context *ctx)
	{
	struct spu *spu = ctx->spu;

	if (spu) {
	spu_unbind_context(spu, ctx);
	spu_reschedule(spu);
	}
	}

	/**
	* spu_yield - yield a physical spu if others are waiting
	* @ctx: spu context to yield
	*
	* Check if there is a higher priority context waiting and if yes
	* unbind @ctx from the physical spu and schedule the highest
	* priority context to run on the freed physical spu instead.
	*/
	void spu_yield(struct spu_context *ctx)
	{
	struct spu *spu;
	int need_yield = 0;

	if (mutex_trylock(&ctx->state_mutex)) {
	if ((spu = ctx->spu) != NULL) {
	int best = sched_find_first_bit(spu_prio->bitmap);
	if (best < MAX_PRIO) {
	pr_debug("%s: yielding SPU %d NODE %d\n",
	__FUNCTION__, spu->number, spu->node);
	spu_deactivate(ctx);
	need_yield = 1;
	}
	}
	mutex_unlock(&ctx->state_mutex);
	}
	if (unlikely(need_yield))
	yield();
	}

	int __init spu_sched_init(void)
	{
	int i;

	spu_sched_wq = create_singlethread_workqueue("spusched");
	if (!spu_sched_wq)
	return 1;

	spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
	if (!spu_prio) {
	printk(KERN_WARNING "%s: Unable to allocate priority queue.\n",
	__FUNCTION__);
	destroy_workqueue(spu_sched_wq);
	return 1;
	}
	for (i = 0; i < MAX_PRIO; i++) {
	INIT_LIST_HEAD(&spu_prio->runq[i]);
	__clear_bit(i, spu_prio->bitmap);
	}
	__set_bit(MAX_PRIO, spu_prio->bitmap);
	for (i = 0; i < MAX_NUMNODES; i++) {
	mutex_init(&spu_prio->active_mutex[i]);
	INIT_LIST_HEAD(&spu_prio->active_list[i]);
	}
	spin_lock_init(&spu_prio->runq_lock);
	return 0;
	}

	void __exit spu_sched_exit(void)
	{
	struct spu spu, tmp;
	int node;

	for (node = 0; node < MAX_NUMNODES; node++) {
	mutex_lock(&spu_prio->active_mutex[node]);
	list_for_each_entry_safe(spu, tmp, &spu_prio->active_list[node],
	list) {
	list_del_init(&spu->list);
	spu_free(spu);
	}
	mutex_unlock(&spu_prio->active_mutex[node]);
	}
	kfree(spu_prio);
	destroy_workqueue(spu_sched_wq);
	}