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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>
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(void)
{
DECLARE_TS_RELEASE_WAIT(wait);
long ret = -ERESTARTSYS;
if (mutex_lock_interruptible(&task_release_lock))
goto out;
list_add(&wait.list, &task_release_list);
mutex_unlock(&task_release_lock);
/* We are enqueued, now we wait for someone to wake us up. */
ret = wait_for_completion_interruptible(&wait.completion);
if (!ret) {
/* Completion succeeded, setup release. */
litmus->release_at(current, wait.ts_release_time
+ current->rt_param.task_params.phase
- current->rt_param.task_params.period);
/* trigger advance to next job release at the programmed time */
ret = complete_job();
} 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++;
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(void)
{
long ret = -EPERM;
struct task_struct *t = current;
if (is_realtime(t))
ret = do_wait_for_ts_release();
return ret;
}
#define ONE_MS 1000000
asmlinkage long sys_release_ts(lt_t __user *__delay)
{
long ret;
lt_t delay;
lt_t start_time;
/* FIXME: check capabilities... */
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;
ret = do_release_ts(start_time + delay);
}
return ret;
}
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