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#include <linux/slab.h>
#include <linux/sched.h>
#include <litmus/litmus.h>
#include <litmus/trace.h>
#include <litmus/event_group.h>
/*
* Return event_queue slot for the given time.
*/
static unsigned int time2slot(lt_t time)
{
return (unsigned int) time2quanta(time, FLOOR) % EVENT_QUEUE_SLOTS;
}
/*
* Executes events from an event_list in priority order.
* Events can requeue themselves when they are called.
*/
static enum hrtimer_restart on_timer(struct hrtimer *timer)
{
unsigned long flags;
struct event_list *el;
struct rt_event *e;
struct list_head *pos, *safe, list;
el = container_of(timer, struct event_list, timer);
raw_spin_lock_irqsave(&el->group->queue_lock, flags);
list_del_init(&el->list);
raw_spin_unlock_irqrestore(&el->group->queue_lock, flags);
/* Empty event list so this event can be requeued */
list_replace_init(&el->events, &list);
/* Fire events */
list_for_each_safe(pos, safe, &list) {
e = list_entry(pos, struct rt_event, list);
TRACE("Dequeueing event with prio %d\n", e->prio);
list_del_init(pos);
e->fire(e->data);
}
return HRTIMER_NORESTART;
}
/*
* Insert event in event-list, respecting priority order.
*/
void insert_event(struct event_list *el, struct rt_event *e)
{
struct list_head *pos;
struct rt_event *queued;
list_for_each_prev(pos, &el->events) {
queued = list_entry(pos, struct rt_event, list);
if (e->prio < queued->prio) {
__list_add(&e->list, pos, pos->next);
return;
}
}
list_add(&e->list, &el->events);
}
/*
* Return event_list for the given event and time. If no event_list
* is being used yet and use_event_heap is 1, will create the list
* and return it. Otherwise it will return NULL.
*/
static struct event_list *get_event_list(struct event_group *group,
struct rt_event *e,
lt_t fire,
int use_event_heap)
{
struct list_head* pos;
struct event_list *el = NULL, *tmp;
unsigned int slot = time2slot(fire);
/* initialize pos for the case that the list is empty */
pos = group->event_queue[slot].next;
list_for_each(pos, &group->event_queue[slot]) {
tmp = list_entry(pos, struct event_list, list);
if (lt_after_eq(fire, tmp->fire_time) &&
lt_before(tmp->fire_time, fire)) {
/* perfect match -- this happens on hyperperiod
* boundaries
*/
el = tmp;
break;
} else if (lt_before(fire, tmp->fire_time)) {
/* we need to insert a new node since rh is
* already in the future
*/
break;
}
}
if (!el && use_event_heap) {
/* use pre-allocated release heap */
tmp = e->event_list;
tmp->fire_time = fire;
tmp->group = group;
/* add to queue */
list_add(&tmp->list, pos->prev);
el = tmp;
}
return el;
}
/*
* Prepare a release heap for a new set of events.
*/
static void reinit_event_list(struct rt_event *e)
{
struct event_list *el = e->event_list;
BUG_ON(hrtimer_cancel(&el->timer));
INIT_LIST_HEAD(&el->events);
atomic_set(&el->info.state, HRTIMER_START_ON_INACTIVE);
}
/**
* add_event() - Add timer to event group.
*/
void add_event(struct event_group *group, struct rt_event *e, lt_t fire)
{
struct event_list *el;
TRACE("Adding event with prio %d @ %llu\n", event->prio, fire);
raw_spin_lock(&group->queue_lock);
el = get_event_list(group, e, fire, 0);
if (!el) {
/* Use our own, but drop lock first */
raw_spin_unlock(&group->queue_lock);
reinit_event_list(e);
raw_spin_lock(&group->queue_lock);
el = get_event_list(group, e, fire, 1);
}
/* Add event to sorted list */
insert_event(el, e);
raw_spin_unlock(&group->queue_lock);
/* Arm timer if we are the owner */
if (el == e->event_list) {
TRACE("Arming timer for %llu\n", fire);
if (group->cpu == smp_processor_id()) {
__hrtimer_start_range_ns(&el->timer,
ns_to_ktime(el->fire_time),
0, HRTIMER_MODE_ABS_PINNED, 0);
} else {
hrtimer_start_on(group->cpu, &el->info,
&el->timer, ns_to_ktime(el->fire_time),
HRTIMER_MODE_ABS_PINNED);
}
} else {
TRACE("Not my timer @%llu", fire);
}
}
/**
* cancel_event() - Remove event from the group.
*/
void cancel_event(struct event_group *group, struct rt_event *e)
{
raw_spin_lock(&group->queue_lock);
list_del_init(&e->list);
raw_spin_unlock(&group->queue_lock);
}
/**
* init_event_group() - Prepare group for events.
*/
void init_event_group(struct event_group *group, lt_t res, int cpu)
{
int i;
group->res = res;
group->cpu = cpu;
for (i = 0; i < EVENT_QUEUE_SLOTS; i++) {
INIT_LIST_HEAD(&group->event_queue[i]);
}
raw_spin_lock_init(&group->queue_lock);
}
struct kmem_cache *event_list_cache;
struct event_list * event_list_alloc(int gfp_flags)
{
struct event_list *el = kmem_cache_alloc(event_list_cache, gfp_flags);
if (el) {
hrtimer_init(&el->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
INIT_LIST_HEAD(&el->list);
el->timer.function = on_timer;
}
return el;
}
void event_list_free(struct event_list *el)
{
hrtimer_cancel(&el->timer);
kmem_cache_free(event_list_cache, el);
}
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