kerrighed_node_t krg_lock_pid_location(pid_t pid)
{
kerrighed_node_t node = KERRIGHED_NODE_ID_NONE;
struct task_kddm_object *obj;
#ifdef CONFIG_KRG_EPM
struct timespec back_off_time = {
.tv_sec = 0,
.tv_nsec = 1000000 /* 1 ms */
};
#endif
if (!(pid & GLOBAL_PID_MASK))
goto out;
for (;;) {
obj = krg_task_readlock(pid);
if (likely(obj)) {
node = obj->node;
} else {
krg_task_unlock(pid);
break;
}
#ifdef CONFIG_KRG_EPM
if (likely(node != KERRIGHED_NODE_ID_NONE))
break;
/*
* Task is migrating.
* Back off and hope that it will stop migrating.
*/
krg_task_unlock(pid);
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(timespec_to_jiffies(&back_off_time) + 1);
#else
break;
#endif
}
out:
return node;
}
void krg_unlock_pid_location(pid_t pid)
{
krg_task_unlock(pid);
}
static int create_pid_kddm_object(struct pid *pid, int early)
{
int nr = pid_knr(pid);
struct pid_kddm_object *obj;
struct task_kddm_object *task_obj;
obj = _kddm_grab_object(pid_kddm_set, nr);
if (IS_ERR(obj)) {
_kddm_put_object(pid_kddm_set, nr);
return PTR_ERR(obj);
}
BUG_ON(!obj);
task_obj = krg_task_readlock(nr);
spin_lock(&pid_kddm_lock);
BUG_ON(early && pid->kddm_obj);
if (!pid->kddm_obj) {
obj->pid = pid;
obj->active = 1;
if (early)
obj->attach_pending = 1;
BUG_ON(obj->task_obj);
if (task_obj) {
BUG_ON(task_obj->pid_obj);
/*
* These rcu_assign_pointer are not really needed,
* but are cleaner :)
*/
rcu_assign_pointer(obj->task_obj, task_obj);
rcu_assign_pointer(obj->task_obj->pid_obj, obj);
}
pid->kddm_obj = obj;
}
BUG_ON(pid->kddm_obj != obj);
spin_unlock(&pid_kddm_lock);
krg_task_unlock(nr);
_kddm_put_object(pid_kddm_set, nr);
return 0;
}
int __krg_pid_link_task(pid_t nr)
{
struct pid *pid;
struct task_kddm_object *task_obj;
int r = 0;
pid = krg_get_pid(nr);
if (!pid) {
r = -ENOMEM;
goto out;
}
task_obj = krg_task_readlock(nr);
__pid_link_task(pid, task_obj);
krg_task_unlock(nr);
krg_end_get_pid(pid);
krg_put_pid(pid);
out:
return r;
}
void __krg_task_unlock(struct task_struct *task)
{
krg_task_unlock(task_pid_knr(task));
}