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/*
* kernel/rt_domain.c
*
* LITMUS real-time infrastructure. This file contains the
* functions that manipulate RT domains. RT domains are an abstraction
* of a ready queue and a release queue.
*/
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <litmus/litmus.h>
#include <litmus/sched_plugin.h>
#include <litmus/sched_trace.h>
#include <litmus/rt_domain.h>
static int dummy_resched(rt_domain_t *rt)
{
return 0;
}
static int dummy_order(struct list_head* a, struct list_head* b)
{
return 0;
}
int release_order(struct list_head* a, struct list_head* b)
{
return earlier_release(
list_entry(a, struct task_struct, rt_list),
list_entry(b, struct task_struct, rt_list));
}
void rt_domain_init(rt_domain_t *rt,
check_resched_needed_t f,
list_cmp_t order)
{
BUG_ON(!rt);
if (!f)
f = dummy_resched;
if (!order)
order = dummy_order;
INIT_LIST_HEAD(&rt->ready_queue);
INIT_LIST_HEAD(&rt->release_queue);
rt->ready_lock = RW_LOCK_UNLOCKED;
rt->release_lock = SPIN_LOCK_UNLOCKED;
rt->check_resched = f;
rt->order = order;
}
/* add_ready - add a real-time task to the rt ready queue. It must be runnable.
* @new: the newly released task
*/
void __add_ready(rt_domain_t* rt, struct task_struct *new)
{
TRACE("rt: adding %s/%d (%llu, %llu) to ready queue at %llu\n",
new->comm, new->pid, get_exec_cost(new), get_rt_period(new),
sched_clock());
if (!list_insert(&new->rt_list, &rt->ready_queue, rt->order))
rt->check_resched(rt);
}
struct task_struct* __take_ready(rt_domain_t* rt)
{
struct task_struct *t = __peek_ready(rt);
/* kick it out of the ready list */
if (t)
list_del(&t->rt_list);
return t;
}
struct task_struct* __peek_ready(rt_domain_t* rt)
{
if (!list_empty(&rt->ready_queue))
return next_ready(rt);
else
return NULL;
}
/* add_release - add a real-time task to the rt release queue.
* @task: the sleeping task
*/
void __add_release(rt_domain_t* rt, struct task_struct *task)
{
TRACE("rt: adding %s/%d (%llu, %llu) rel=%llu to release queue\n",
task->comm, task->pid, get_exec_cost(task), get_rt_period(task),
get_release(task));
list_insert(&task->rt_list, &rt->release_queue, release_order);
}
void __release_pending(rt_domain_t* rt)
{
struct list_head *pos, *save;
struct task_struct *queued;
lt_t now = sched_clock();
list_for_each_safe(pos, save, &rt->release_queue) {
queued = list_entry(pos, struct task_struct, rt_list);
if (likely(is_released(queued, now))) {
/* this one is ready to go*/
list_del(pos);
set_rt_flags(queued, RT_F_RUNNING);
sched_trace_job_release(queued);
/* now it can be picked up */
barrier();
add_ready(rt, queued);
}
else
/* the release queue is ordered */
break;
}
}
void try_release_pending(rt_domain_t* rt)
{
unsigned long flags;
if (spin_trylock_irqsave(&rt->release_lock, flags)) {
__release_pending(rt);
spin_unlock_irqrestore(&rt->release_lock, flags);
}
}
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