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/* litmus/sync.c - Support for synchronous and asynchronous task system releases.
*
*
*/
#include <asm/atomic.h>
#include <asm/uaccess.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <litmus/litmus.h>
#include <litmus/sched_plugin.h>
#include <litmus/jobs.h>
#include <litmus/sched_trace.h>
#include <litmus/budget.h>
struct ts_release_wait {
struct list_head list;
struct completion completion;
lt_t ts_release_time;
};
#define DECLARE_TS_RELEASE_WAIT(symb) \
struct ts_release_wait symb = \
{ \
LIST_HEAD_INIT(symb.list), \
COMPLETION_INITIALIZER_ONSTACK(symb.completion), \
0 \
}
static LIST_HEAD(task_release_list);
static DEFINE_MUTEX(task_release_lock);
static long do_wait_for_ts_release(struct timespec *wake)
{
DECLARE_TS_RELEASE_WAIT(wait);
long ret = -ERESTARTSYS;
struct task_struct *t = current;
int is_rt = is_realtime(t);
#if defined(CONFIG_REALTIME_AUX_TASKS) || defined(CONFIG_LITMUS_NVIDIA)
DECLARE_WORKER_VIS_FLAGS(vis_flags);
#endif
if (mutex_lock_interruptible(&task_release_lock))
goto out;
list_add(&wait.list, &task_release_list);
mutex_unlock(&task_release_lock);
if (is_rt) {
#if defined(CONFIG_REALTIME_AUX_TASKS) || defined(CONFIG_LITMUS_NVIDIA)
hide_from_workers(t, &vis_flags);
#endif
bt_flag_set(t, BTF_WAITING_FOR_RELEASE);
mb();
budget_state_machine(t,on_exit); // do this here and not in schedule()?
}
TRACE_TASK(t, "waiting for ts release.\n");
if (is_rt)
BUG_ON(!bt_flag_is_set(t, BTF_WAITING_FOR_RELEASE));
/* We are enqueued, now we wait for someone to wake us up. */
ret = wait_for_completion_interruptible(&wait.completion);
TRACE_TASK(t, "released by ts release!\n");
if (is_rt) {
bt_flag_clear(t, BTF_WAITING_FOR_RELEASE);
#if defined(CONFIG_REALTIME_AUX_TASKS) || defined(CONFIG_LITMUS_NVIDIA)
show_to_workers(t, &vis_flags);
#endif
}
if (!ret) {
if (is_rt) {
lt_t phasedRelease = wait.ts_release_time
+ t->rt_param.task_params.phase;
*wake = ns_to_timespec(phasedRelease);
/* Setting this flag before releasing ensures that this CPU
* will be the next CPU to requeue the task on a ready or
* release queue.
*/
tsk_rt(t)->completed = 1;
tsk_rt(t)->job_params.backlog = 0;
tsk_rt(t)->job_params.is_backlogged_job = 0;
tsk_rt(t)->budget.suspend_timestamp = 0;
bt_flag_clear(t, BTF_BUDGET_EXHAUSTED);
mb();
/* completion succeeded, set up release. subtract off
* period because schedule()->job_completion() will
* advances us to the correct time */
//litmus->release_at(t, phasedRelease - t->rt_param.task_params.period);
setup_release(t, phasedRelease - t->rt_param.task_params.period); // breaks pfair
schedule();
}
else {
*wake = ns_to_timespec(wait.ts_release_time);
}
} else {
/* We were interrupted, must cleanup list. */
mutex_lock(&task_release_lock);
if (!wait.completion.done)
list_del(&wait.list);
mutex_unlock(&task_release_lock);
}
out:
return ret;
}
int count_tasks_waiting_for_release(void)
{
int task_count = 0;
struct list_head *pos;
mutex_lock(&task_release_lock);
list_for_each(pos, &task_release_list) {
task_count++;
}
mutex_unlock(&task_release_lock);
return task_count;
}
static long do_release_ts(lt_t start)
{
long task_count = 0;
struct list_head *pos, *safe;
struct ts_release_wait *wait;
if (mutex_lock_interruptible(&task_release_lock)) {
task_count = -ERESTARTSYS;
goto out;
}
TRACE("<<<<<< synchronous task system release >>>>>>\n");
sched_trace_sys_release(&start);
task_count = 0;
list_for_each_safe(pos, safe, &task_release_list) {
wait = (struct ts_release_wait*)
list_entry(pos, struct ts_release_wait, list);
task_count++;
/* RT tasks can be delayed. Non-RT tasks are released
immediately. */
wait->ts_release_time = start;
complete(&wait->completion);
}
/* clear stale list */
INIT_LIST_HEAD(&task_release_list);
mutex_unlock(&task_release_lock);
out:
return task_count;
}
asmlinkage long sys_wait_for_ts_release(struct timespec __user *__wake)
{
struct timespec wake;
long ret = -EPERM;
ret = do_wait_for_ts_release(&wake);
if (__wake && access_ok(VERIFY_WRITE, __wake, sizeof(struct timespec))) {
__copy_to_user(__wake, &wake, sizeof(wake));
}
return ret;
}
#define ONE_MS 1000000
asmlinkage long sys_release_ts(lt_t __user *__delay)
{
long ret = 0;
lt_t delay = 0;
lt_t start_time;
/* FIXME: check capabilities... */
if (__delay)
ret = copy_from_user(&delay, __delay, sizeof(delay));
if (ret == 0) {
/* round up to next larger integral millisecond */
// start_time = ((litmus_clock() / ONE_MS) + 1) * ONE_MS;
start_time = litmus_clock();
/* Note: Non-rt tasks that participate in a sync release cannot be
delayed. They will be released immediately. */
ret = do_release_ts(start_time + delay);
}
return ret;
}
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