/*! Up or "V" operation on a semaphore. Increments SEMA's value
and wakes up one thread of those waiting for SEMA, if any.
This function may be called from an interrupt handler. */
void sema_up(struct semaphore *sema) {
enum intr_level old_level;
ASSERT(sema != NULL);
old_level = intr_disable();
sema->value++;
if (!list_empty(&sema->waiters)) {
struct list_elem *e = list_begin(&sema->waiters);
struct thread *wake_thread = list_entry(e, struct thread, elem);
int max_priority = compute_priority(wake_thread);
for (e = list_next(e); e != list_end(&sema->waiters);
e = list_next(e)) {
struct thread *t = list_entry(e, struct thread, elem);
int priority = compute_priority(t);
if (priority > max_priority) {
max_priority = priority;
wake_thread = t;
}
}
list_remove(&wake_thread->elem);
thread_unblock(wake_thread);
if (max_priority >= thread_get_priority()) {
thread_yield();
}
}
intr_set_level(old_level);
}
void
heap_increase_priority(heap_t *heap,
heap_item_t* item,
double new_priority,
double (*compute_priority)(heap_item_t*),
void (*set_priority)(heap_item_t*,double)) {
// assumes that priority and node mass are one and the same
double new_mass;
if (new_priority < compute_priority(item)) {
fprintf(stderr,"New priority is smaller than current priority.\n");
return;
}
new_mass = new_priority - item->node_mass;
set_priority(item,new_priority);
item->node_mass = new_priority;
item->subtree_mass += new_mass;
while (item->index > 0 && compute_priority(heap_parent(heap, item)) < compute_priority(item)) {
heap_parent(heap,item)->subtree_mass += new_mass;
heap_exchange(heap, item, heap_parent(heap, item));
item = heap_parent(heap, item);
}
while (item->index > 0) {
heap_parent(heap,item)->subtree_mass += new_mass;
item = heap_parent(heap, item);
}
}
/*
* thread_depress_abort:
*
* Prematurely abort priority depression if there is one.
*/
kern_return_t
thread_depress_abort(thread_t thread)
{
spl_t s;
if (thread == THREAD_NULL)
return(KERN_INVALID_ARGUMENT);
s = splsched();
thread_lock(thread);
/*
* Only restore priority if thread is depressed.
*/
if (thread->depress_priority >= 0) {
reset_timeout_check(&thread->depress_timer);
thread->priority = thread->depress_priority;
thread->depress_priority = -1;
compute_priority(thread, FALSE);
}
thread_unlock(thread);
(void) splx(s);
return(KERN_SUCCESS);
}
/*! Acquires LOCK, sleeping until it becomes available if
necessary. The lock must not already be held by the current
thread.
This function may sleep, so it must not be called within an
interrupt handler. This function may be called with
interrupts disabled, but interrupts will be turned back on if
we need to sleep. */
void lock_acquire(struct lock *lock) {
ASSERT(lock != NULL);
ASSERT(!intr_context());
ASSERT(!lock_held_by_current_thread(lock));
struct thread *cur = thread_current();
if (compute_priority(cur) > lock->donated_priority) {
lock_donate_priority(lock, compute_priority(cur));
}
cur->lock_waiting = lock;
sema_down(&lock->semaphore);
cur->lock_waiting = NULL;
lock->holder = cur;
/* TODO: recompute lock donation priority */
list_push_back(&cur->lock_list, &lock->elem);
}
/*
* Routine: lck_mtx_unlock_wakeup
*
* Invoked on unlock when there is contention.
*
* Called with the interlock locked.
*/
void
lck_mtx_unlock_wakeup (
lck_mtx_t *lck,
thread_t holder)
{
thread_t thread = current_thread();
lck_mtx_t *mutex;
if (lck->lck_mtx_tag != LCK_MTX_TAG_INDIRECT)
mutex = lck;
else
mutex = &lck->lck_mtx_ptr->lck_mtx;
KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_LOCKS, LCK_MTX_UNLCK_WAKEUP_CODE) | DBG_FUNC_START, (int)lck, (int)holder, 0, 0, 0);
if (thread != holder)
panic("lck_mtx_unlock_wakeup: mutex %p holder %p\n", mutex, holder);
if (thread->promotions > 0) {
spl_t s = splsched();
thread_lock(thread);
if ( --thread->promotions == 0 &&
(thread->sched_mode & TH_MODE_PROMOTED) ) {
thread->sched_mode &= ~TH_MODE_PROMOTED;
if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
KERNEL_DEBUG_CONSTANT(
MACHDBG_CODE(DBG_MACH_SCHED,MACH_DEMOTE) | DBG_FUNC_NONE,
thread->sched_pri, DEPRESSPRI, 0, (int)lck, 0);
set_sched_pri(thread, DEPRESSPRI);
}
else {
if (thread->priority < thread->sched_pri) {
KERNEL_DEBUG_CONSTANT(
MACHDBG_CODE(DBG_MACH_SCHED,MACH_DEMOTE) |
DBG_FUNC_NONE,
thread->sched_pri, thread->priority,
0, (int)lck, 0);
}
compute_priority(thread, FALSE);
}
}
thread_unlock(thread);
splx(s);
}
assert(mutex->lck_mtx_waiters > 0);
thread_wakeup_one((event_t)(((unsigned int*)lck)+(sizeof(lck_mtx_t)-1)/sizeof(unsigned int)));
KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_LOCKS, LCK_MTX_UNLCK_WAKEUP_CODE) | DBG_FUNC_END, 0, 0, 0, 0, 0);
}
/*
* thread_depress_timeout:
*
* Timeout routine for priority depression.
*/
void
thread_depress_timeout(thread_t thread)
{
spl_t s;
s = splsched();
thread_lock(thread);
/*
* If we lose a race with thread_depress_abort,
* then depress_priority might be -1.
*/
if (thread->depress_priority >= 0) {
thread->priority = thread->depress_priority;
thread->depress_priority = -1;
compute_priority(thread, FALSE);
}
thread_unlock(thread);
(void) splx(s);
}
/*
* Create a new thread.
* Doesn't start the thread running.
*/
static kern_return_t
thread_create_internal(
task_t parent_task,
integer_t priority,
thread_continue_t continuation,
thread_t *out_thread)
{
thread_t new_thread;
static thread_t first_thread;
/*
* Allocate a thread and initialize static fields
*/
if (first_thread == NULL)
new_thread = first_thread = current_thread();
else
new_thread = (thread_t)zalloc(thread_zone);
if (new_thread == NULL)
return (KERN_RESOURCE_SHORTAGE);
if (new_thread != first_thread)
*new_thread = thread_template;
#ifdef MACH_BSD
{
new_thread->uthread = uthread_alloc(parent_task, new_thread);
if (new_thread->uthread == NULL) {
zfree(thread_zone, new_thread);
return (KERN_RESOURCE_SHORTAGE);
}
}
#endif /* MACH_BSD */
if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
{
void *ut = new_thread->uthread;
new_thread->uthread = NULL;
/* cred free may not be necessary */
uthread_cleanup(parent_task, ut, parent_task->bsd_info);
uthread_cred_free(ut);
uthread_zone_free(ut);
}
#endif /* MACH_BSD */
zfree(thread_zone, new_thread);
return (KERN_FAILURE);
}
new_thread->task = parent_task;
thread_lock_init(new_thread);
wake_lock_init(new_thread);
mutex_init(&new_thread->mutex, 0);
ipc_thread_init(new_thread);
queue_init(&new_thread->held_ulocks);
new_thread->continuation = continuation;
mutex_lock(&tasks_threads_lock);
task_lock(parent_task);
if ( !parent_task->active ||
(parent_task->thread_count >= THREAD_MAX &&
parent_task != kernel_task)) {
task_unlock(parent_task);
mutex_unlock(&tasks_threads_lock);
#ifdef MACH_BSD
{
void *ut = new_thread->uthread;
new_thread->uthread = NULL;
uthread_cleanup(parent_task, ut, parent_task->bsd_info);
/* cred free may not be necessary */
uthread_cred_free(ut);
uthread_zone_free(ut);
}
#endif /* MACH_BSD */
ipc_thread_disable(new_thread);
ipc_thread_terminate(new_thread);
machine_thread_destroy(new_thread);
zfree(thread_zone, new_thread);
return (KERN_FAILURE);
}
task_reference_internal(parent_task);
/* Cache the task's map */
new_thread->map = parent_task->map;
/* Chain the thread onto the task's list */
queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
parent_task->thread_count++;
/* So terminating threads don't need to take the task lock to decrement */
hw_atomic_add(&parent_task->active_thread_count, 1);
queue_enter(&threads, new_thread, thread_t, threads);
threads_count++;
timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);
/* Set the thread's scheduling parameters */
if (parent_task != kernel_task)
new_thread->sched_mode |= TH_MODE_TIMESHARE;
new_thread->max_priority = parent_task->max_priority;
new_thread->task_priority = parent_task->priority;
new_thread->priority = (priority < 0)? parent_task->priority: priority;
if (new_thread->priority > new_thread->max_priority)
new_thread->priority = new_thread->max_priority;
new_thread->importance =
new_thread->priority - new_thread->task_priority;
new_thread->sched_stamp = sched_tick;
new_thread->pri_shift = sched_pri_shift;
compute_priority(new_thread, FALSE);
new_thread->active = TRUE;
*out_thread = new_thread;
{
long dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;
kdbg_trace_data(parent_task->bsd_info, &dbg_arg2);
KERNEL_DEBUG_CONSTANT(
TRACEDBG_CODE(DBG_TRACE_DATA, 1) | DBG_FUNC_NONE,
(vm_address_t)new_thread, dbg_arg2, 0, 0, 0);
kdbg_trace_string(parent_task->bsd_info,
&dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);
KERNEL_DEBUG_CONSTANT(
TRACEDBG_CODE(DBG_TRACE_STRING, 1) | DBG_FUNC_NONE,
dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
}
DTRACE_PROC1(lwp__create, thread_t, *out_thread);
return (KERN_SUCCESS);
}
/*
* Create a new thread.
* Doesn't start the thread running.
*/
static kern_return_t
thread_create_internal(
task_t parent_task,
integer_t priority,
thread_continue_t continuation,
int options,
#define TH_OPTION_NONE 0x00
#define TH_OPTION_NOCRED 0x01
#define TH_OPTION_NOSUSP 0x02
thread_t *out_thread)
{
thread_t new_thread;
static thread_t first_thread;
/*
* Allocate a thread and initialize static fields
*/
if (first_thread == THREAD_NULL)
new_thread = first_thread = current_thread();
else
new_thread = (thread_t)zalloc(thread_zone);
if (new_thread == THREAD_NULL)
return (KERN_RESOURCE_SHORTAGE);
if (new_thread != first_thread)
*new_thread = thread_template;
#ifdef MACH_BSD
new_thread->uthread = uthread_alloc(parent_task, new_thread, (options & TH_OPTION_NOCRED) != 0);
if (new_thread->uthread == NULL) {
zfree(thread_zone, new_thread);
return (KERN_RESOURCE_SHORTAGE);
}
#endif /* MACH_BSD */
if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
void *ut = new_thread->uthread;
new_thread->uthread = NULL;
/* cred free may not be necessary */
uthread_cleanup(parent_task, ut, parent_task->bsd_info);
uthread_cred_free(ut);
uthread_zone_free(ut);
#endif /* MACH_BSD */
zfree(thread_zone, new_thread);
return (KERN_FAILURE);
}
new_thread->task = parent_task;
thread_lock_init(new_thread);
wake_lock_init(new_thread);
lck_mtx_init(&new_thread->mutex, &thread_lck_grp, &thread_lck_attr);
ipc_thread_init(new_thread);
queue_init(&new_thread->held_ulocks);
new_thread->continuation = continuation;
lck_mtx_lock(&tasks_threads_lock);
task_lock(parent_task);
if ( !parent_task->active || parent_task->halting ||
((options & TH_OPTION_NOSUSP) != 0 &&
parent_task->suspend_count > 0) ||
(parent_task->thread_count >= task_threadmax &&
parent_task != kernel_task) ) {
task_unlock(parent_task);
lck_mtx_unlock(&tasks_threads_lock);
#ifdef MACH_BSD
{
void *ut = new_thread->uthread;
new_thread->uthread = NULL;
uthread_cleanup(parent_task, ut, parent_task->bsd_info);
/* cred free may not be necessary */
uthread_cred_free(ut);
uthread_zone_free(ut);
}
#endif /* MACH_BSD */
ipc_thread_disable(new_thread);
ipc_thread_terminate(new_thread);
lck_mtx_destroy(&new_thread->mutex, &thread_lck_grp);
machine_thread_destroy(new_thread);
zfree(thread_zone, new_thread);
return (KERN_FAILURE);
}
/* New threads inherit any default state on the task */
machine_thread_inherit_taskwide(new_thread, parent_task);
task_reference_internal(parent_task);
/* Cache the task's map */
new_thread->map = parent_task->map;
/* Chain the thread onto the task's list */
queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
parent_task->thread_count++;
/* So terminating threads don't need to take the task lock to decrement */
hw_atomic_add(&parent_task->active_thread_count, 1);
/* Protected by the tasks_threads_lock */
new_thread->thread_id = ++thread_unique_id;
queue_enter(&threads, new_thread, thread_t, threads);
threads_count++;
timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);
#if CONFIG_COUNTERS
/*
* If parent task has any reservations, they need to be propagated to this
* thread.
*/
new_thread->t_chud = (TASK_PMC_FLAG == (parent_task->t_chud & TASK_PMC_FLAG)) ?
THREAD_PMC_FLAG : 0U;
#endif
/* Set the thread's scheduling parameters */
if (parent_task != kernel_task)
new_thread->sched_mode |= TH_MODE_TIMESHARE;
new_thread->max_priority = parent_task->max_priority;
new_thread->task_priority = parent_task->priority;
new_thread->priority = (priority < 0)? parent_task->priority: priority;
if (new_thread->priority > new_thread->max_priority)
new_thread->priority = new_thread->max_priority;
new_thread->importance =
new_thread->priority - new_thread->task_priority;
new_thread->sched_stamp = sched_tick;
new_thread->pri_shift = sched_pri_shift;
compute_priority(new_thread, FALSE);
new_thread->active = TRUE;
*out_thread = new_thread;
{
long dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;
kdbg_trace_data(parent_task->bsd_info, &dbg_arg2);
KERNEL_DEBUG_CONSTANT(
TRACEDBG_CODE(DBG_TRACE_DATA, 1) | DBG_FUNC_NONE,
(vm_address_t)(uintptr_t)thread_tid(new_thread), dbg_arg2, 0, 0, 0);
kdbg_trace_string(parent_task->bsd_info,
&dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);
KERNEL_DEBUG_CONSTANT(
TRACEDBG_CODE(DBG_TRACE_STRING, 1) | DBG_FUNC_NONE,
dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
}
DTRACE_PROC1(lwp__create, thread_t, *out_thread);
return (KERN_SUCCESS);
}
