/*
* Routine: wait_queue_assert_wait64
* Purpose:
* Insert the current thread into the supplied wait queue
* waiting for a particular event to be posted to that queue.
* Conditions:
* nothing of interest locked.
*/
wait_result_t
wait_queue_assert_wait64(
wait_queue_t wq,
event64_t event,
wait_interrupt_t interruptible)
{
spl_t s;
wait_result_t ret;
thread_t cur_thread = current_thread();
/* If it is an invalid wait queue, you cant wait on it */
if (!wait_queue_is_valid(wq)) {
thread_t thread = current_thread();
return (thread->wait_result = THREAD_RESTART);
}
s = splsched();
wait_queue_lock(wq);
thread_lock(cur_thread);
ret = wait_queue_assert_wait64_locked(wq, event, interruptible, cur_thread);
thread_unlock(cur_thread);
wait_queue_unlock(wq);
splx(s);
return(ret);
}
/*
* Routine: wait_queue_assert_wait
* Purpose:
* Insert the current thread into the supplied wait queue
* waiting for a particular event to be posted to that queue.
*
* Conditions:
* nothing of interest locked.
*/
wait_result_t
wait_queue_assert_wait(
wait_queue_t wq,
event_t event,
wait_interrupt_t interruptible,
uint64_t deadline)
{
spl_t s;
wait_result_t ret;
thread_t thread = current_thread();
/* If it is an invalid wait queue, you can't wait on it */
if (!wait_queue_is_valid(wq))
return (thread->wait_result = THREAD_RESTART);
s = splsched();
wait_queue_lock(wq);
thread_lock(thread);
ret = wait_queue_assert_wait64_locked(wq, CAST_DOWN(event64_t,event),
interruptible, deadline, thread);
thread_unlock(thread);
wait_queue_unlock(wq);
splx(s);
return(ret);
}
/*
* Routine: wait_queue_wakeup64_thread
* Purpose:
* Wakeup the particular thread that was specified if and only
* it was in this wait queue (or one of it's set's queues)
* and waiting on the specified event.
*
* This is much safer than just removing the thread from
* whatever wait queue it happens to be on. For instance, it
* may have already been awoken from the wait you intended to
* interrupt and waited on something else (like another
* semaphore).
* Conditions:
* nothing of interest locked
* we need to assume spl needs to be raised
* Returns:
* KERN_SUCCESS - the thread was found waiting and awakened
* KERN_NOT_WAITING - the thread was not waiting here
*/
kern_return_t
wait_queue_wakeup64_thread(
wait_queue_t wq,
event64_t event,
thread_t thread,
wait_result_t result)
{
kern_return_t res;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
res = _wait_queue_select64_thread(wq, event, thread);
wait_queue_unlock(wq);
if (res == KERN_SUCCESS) {
res = thread_go(thread, result);
assert(res == KERN_SUCCESS);
thread_unlock(thread);
splx(s);
return res;
}
splx(s);
return KERN_NOT_WAITING;
}
/*
* Routine: _wait_queue_select64_one
* Purpose:
* Select the best thread off a wait queue that meet the
* supplied criteria.
* Conditions:
* at splsched
* wait queue locked
* possibly recursive
* Returns:
* a locked thread - if one found
* Note:
* This is where the sync policy of the wait queue comes
* into effect. For now, we just assume FIFO.
*/
static thread_t
_wait_queue_select64_one(
wait_queue_t wq,
event64_t event)
{
wait_queue_element_t wq_element;
wait_queue_element_t wqe_next;
thread_t t = THREAD_NULL;
queue_t q;
assert(wq->wq_fifo);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wqe_next = (wait_queue_element_t)
queue_next((queue_t) wq_element);
/*
* We may have to recurse if this is a compound wait queue.
*/
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_t set_queue;
/*
* We have to check the set wait queue.
*/
set_queue = (wait_queue_t)wql->wql_setqueue;
wait_queue_lock(set_queue);
if (! wait_queue_empty(set_queue)) {
t = _wait_queue_select64_one(set_queue, event);
}
wait_queue_unlock(set_queue);
if (t != THREAD_NULL)
return t;
} else {
/*
* Otherwise, its a thread. If it is waiting on
* the event we are posting to this queue, pull
* it off the queue and stick it in out wake_queue.
*/
thread_t t = (thread_t)wq_element;
if (t->wait_event == event) {
thread_lock(t);
remqueue(q, (queue_entry_t) t);
t->wait_queue = WAIT_QUEUE_NULL;
t->wait_event = NO_EVENT64;
t->at_safe_point = FALSE;
return t; /* still locked */
}
}
wq_element = wqe_next;
}
return THREAD_NULL;
}
/*
* Routine: wait_queue_wakeup_all
* Purpose:
* Wakeup some number of threads that are in the specified
* wait queue and waiting on the specified event.
* Conditions:
* Nothing locked
* Returns:
* KERN_SUCCESS - Threads were woken up
* KERN_NOT_WAITING - No threads were waiting <wq,event> pair
*/
kern_return_t
wait_queue_wakeup_all(
wait_queue_t wq,
event_t event,
wait_result_t result)
{
kern_return_t ret;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
// if(!wq->wq_interlock.lock_data) { /* (BRINGUP */
// panic("wait_queue_wakeup_all: we did not get the lock on %p\n", wq); /* (BRINGUP) */
// }
ret = wait_queue_wakeup64_all_locked(
wq, CAST_DOWN(event64_t,event),
result, TRUE);
/* lock released */
splx(s);
return ret;
}
/*
* Routine: wait_queue_wakeup_one
* Purpose:
* Wakeup the most appropriate thread that is in the specified
* wait queue for the specified event.
* Conditions:
* Nothing locked
* Returns:
* KERN_SUCCESS - Thread was woken up
* KERN_NOT_WAITING - No thread was waiting <wq,event> pair
*/
kern_return_t
wait_queue_wakeup_one(
wait_queue_t wq,
event_t event,
wait_result_t result)
{
thread_t thread;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
thread = _wait_queue_select64_one(wq, (event64_t)((uint32_t)event));
wait_queue_unlock(wq);
if (thread) {
kern_return_t res;
res = thread_go_locked(thread, result);
assert(res == KERN_SUCCESS);
thread_unlock(thread);
splx(s);
return res;
}
splx(s);
return KERN_NOT_WAITING;
}
/*
* Routine: wait_queue_link_internal
* Purpose:
* Insert a set wait queue into a wait queue. This
* requires us to link the two together using a wait_queue_link
* structure that was provided.
* Conditions:
* The wait queue being inserted must be inited as a set queue
* The wait_queue_link structure must already be properly typed
*/
static
kern_return_t
wait_queue_link_internal(
wait_queue_t wq,
wait_queue_set_t wq_set,
wait_queue_link_t wql)
{
wait_queue_element_t wq_element;
queue_t q;
spl_t s;
if (!wait_queue_is_valid(wq) || !wait_queue_is_set(wq_set))
return KERN_INVALID_ARGUMENT;
/*
* There are probably fewer threads and sets associated with
* the wait queue than there are wait queues associated with
* the set. So let's validate it that way.
*/
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
if ((wq_element->wqe_type == WAIT_QUEUE_LINK ||
wq_element->wqe_type == WAIT_QUEUE_LINK_NOALLOC) &&
((wait_queue_link_t)wq_element)->wql_setqueue == wq_set) {
wait_queue_unlock(wq);
splx(s);
return KERN_ALREADY_IN_SET;
}
wq_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
}
/*
* Not already a member, so we can add it.
*/
wqs_lock(wq_set);
WAIT_QUEUE_SET_CHECK(wq_set);
assert(wql->wql_type == WAIT_QUEUE_LINK ||
wql->wql_type == WAIT_QUEUE_LINK_NOALLOC);
wql->wql_queue = wq;
wql_clear_prepost(wql);
queue_enter(&wq->wq_queue, wql, wait_queue_link_t, wql_links);
wql->wql_setqueue = wq_set;
queue_enter(&wq_set->wqs_setlinks, wql, wait_queue_link_t, wql_setlinks);
wqs_unlock(wq_set);
wait_queue_unlock(wq);
splx(s);
return KERN_SUCCESS;
}
kern_return_t
wait_queue_unlink_all(
wait_queue_t wq)
{
wait_queue_element_t wq_element;
wait_queue_element_t wq_next_element;
wait_queue_set_t wq_set;
wait_queue_link_t wql;
queue_head_t links_queue_head;
queue_t links = &links_queue_head;
queue_t q;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
queue_init(links);
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
boolean_t alloced;
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wq_next_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
alloced = (wq_element->wqe_type == WAIT_QUEUE_LINK);
if (alloced || wq_element->wqe_type == WAIT_QUEUE_LINK_NOALLOC) {
wql = (wait_queue_link_t)wq_element;
wq_set = wql->wql_setqueue;
wqs_lock(wq_set);
wait_queue_unlink_locked(wq, wq_set, wql);
wqs_unlock(wq_set);
if (alloced)
enqueue(links, &wql->wql_links);
}
wq_element = wq_next_element;
}
wait_queue_unlock(wq);
splx(s);
while(!queue_empty(links)) {
wql = (wait_queue_link_t) dequeue(links);
zfree(_wait_queue_link_zone, wql);
}
return(KERN_SUCCESS);
}
/*
* Routine: wait_queue_select64_thread
* Purpose:
* Look for a thread and remove it from the queues, if
* (and only if) the thread is waiting on the supplied
* <wait_queue, event> pair.
* Conditions:
* at splsched
* wait queue locked
* possibly recursive
* Returns:
* KERN_NOT_WAITING: Thread is not waiting here.
* KERN_SUCCESS: It was, and is now removed (returned locked)
*/
static kern_return_t
_wait_queue_select64_thread(
wait_queue_t wq,
event64_t event,
thread_t thread)
{
wait_queue_element_t wq_element;
wait_queue_element_t wqe_next;
kern_return_t res = KERN_NOT_WAITING;
queue_t q = &wq->wq_queue;
thread_lock(thread);
if ((thread->wait_queue == wq) && (thread->wait_event == event)) {
remqueue(q, (queue_entry_t) thread);
thread->at_safe_point = FALSE;
thread->wait_event = NO_EVENT64;
thread->wait_queue = WAIT_QUEUE_NULL;
/* thread still locked */
return KERN_SUCCESS;
}
thread_unlock(thread);
/*
* The wait_queue associated with the thread may be one of this
* wait queue's sets. Go see. If so, removing it from
* there is like removing it from here.
*/
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wqe_next = (wait_queue_element_t)
queue_next((queue_t) wq_element);
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_t set_queue;
set_queue = (wait_queue_t)wql->wql_setqueue;
wait_queue_lock(set_queue);
if (! wait_queue_empty(set_queue)) {
res = _wait_queue_select64_thread(set_queue,
event,
thread);
}
wait_queue_unlock(set_queue);
if (res == KERN_SUCCESS)
return KERN_SUCCESS;
}
wq_element = wqe_next;
}
return res;
}
kern_return_t
wait_queue_unlink_all(
wait_queue_t wq)
{
wait_queue_element_t wq_element;
wait_queue_element_t wq_next_element;
wait_queue_set_t wq_set;
wait_queue_link_t wql;
queue_head_t links_queue_head;
queue_t links = &links_queue_head;
queue_t q;
spl_t s;
if (!wait_queue_is_queue(wq)) {
return KERN_INVALID_ARGUMENT;
}
queue_init(links);
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wq_next_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wql = (wait_queue_link_t)wq_element;
wq_set = wql->wql_setqueue;
wqs_lock(wq_set);
wait_queue_unlink_locked(wq, wq_set, wql);
wqs_unlock(wq_set);
enqueue(links, &wql->wql_links);
}
wq_element = wq_next_element;
}
wait_queue_unlock(wq);
splx(s);
while(!queue_empty(links)) {
wql = (wait_queue_link_t) dequeue(links);
kfree((vm_offset_t) wql, sizeof(struct wait_queue_link));
}
return(KERN_SUCCESS);
}
/*
* Routine: wait_queue_unlink
* Purpose:
* Remove the linkage between a wait queue and a set,
* freeing the linkage structure.
* Conditions:
* The wait queue being must be a member set queue
*/
kern_return_t
wait_queue_unlink(
wait_queue_t wq,
wait_queue_set_t wq_set)
{
wait_queue_element_t wq_element;
wait_queue_link_t wql;
queue_t q;
spl_t s;
if (!wait_queue_is_valid(wq) || !wait_queue_is_set(wq_set)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
if (wq_element->wqe_type == WAIT_QUEUE_LINK ||
wq_element->wqe_type == WAIT_QUEUE_LINK_NOALLOC) {
wql = (wait_queue_link_t)wq_element;
if (wql->wql_setqueue == wq_set) {
boolean_t alloced;
alloced = (wql->wql_type == WAIT_QUEUE_LINK);
wqs_lock(wq_set);
wait_queue_unlink_locked(wq, wq_set, wql);
wqs_unlock(wq_set);
wait_queue_unlock(wq);
splx(s);
if (alloced)
zfree(_wait_queue_link_zone, wql);
return KERN_SUCCESS;
}
}
wq_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
}
wait_queue_unlock(wq);
splx(s);
return KERN_NOT_IN_SET;
}
/*
* Routine: wait_queue_member
* Purpose:
* Indicate if this set queue is a member of the queue
* Conditions:
* The set queue is just that, a set queue
*/
boolean_t
wait_queue_member(
wait_queue_t wq,
wait_queue_set_t wq_set)
{
boolean_t ret;
spl_t s;
if (!wait_queue_is_set(wq_set))
return FALSE;
s = splsched();
wait_queue_lock(wq);
ret = wait_queue_member_locked(wq, wq_set);
wait_queue_unlock(wq);
splx(s);
return ret;
}
/*
* Routine: wait_queue_wakeup64_all
* Purpose:
* Wakeup some number of threads that are in the specified
* wait queue and waiting on the specified event.
* Conditions:
* Nothing locked
* Returns:
* KERN_SUCCESS - Threads were woken up
* KERN_NOT_WAITING - No threads were waiting <wq,event> pair
*/
kern_return_t
wait_queue_wakeup64_all(
wait_queue_t wq,
event64_t event,
wait_result_t result)
{
kern_return_t ret;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
ret = wait_queue_wakeup64_all_locked(wq, event, result, TRUE);
/* lock released */
splx(s);
return ret;
}
/*
* Routine: wait_queue_wakeup_one
* Purpose:
* Wakeup the most appropriate thread that is in the specified
* wait queue for the specified event.
* Conditions:
* Nothing locked
* Returns:
* KERN_SUCCESS - Thread was woken up
* KERN_NOT_WAITING - No thread was waiting <wq,event> pair
*/
kern_return_t
wait_queue_wakeup_one(
wait_queue_t wq,
event_t event,
wait_result_t result,
int priority)
{
thread_t thread;
spl_t s;
if (!wait_queue_is_valid(wq)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
thread = _wait_queue_select64_one(wq, CAST_DOWN(event64_t,event));
wait_queue_unlock(wq);
if (thread) {
kern_return_t res;
if (thread->sched_pri < priority) {
if (priority <= MAXPRI) {
set_sched_pri(thread, priority);
thread->was_promoted_on_wakeup = 1;
thread->sched_flags |= TH_SFLAG_PROMOTED;
}
}
res = thread_go(thread, result);
assert(res == KERN_SUCCESS);
thread_unlock(thread);
splx(s);
return res;
}
splx(s);
return KERN_NOT_WAITING;
}
/*
* Routine: wait_queue_unlink
* Purpose:
* Remove the linkage between a wait queue and a set,
* freeing the linkage structure.
* Conditions:
* The wait queue being must be a member set queue
*/
kern_return_t
wait_queue_unlink(
wait_queue_t wq,
wait_queue_set_t wq_set)
{
wait_queue_element_t wq_element;
wait_queue_link_t wql;
queue_t q;
spl_t s;
if (!wait_queue_is_queue(wq) || !wait_queue_is_set(wq_set)) {
return KERN_INVALID_ARGUMENT;
}
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wql = (wait_queue_link_t)wq_element;
if (wql->wql_setqueue == wq_set) {
wqs_lock(wq_set);
wait_queue_unlink_locked(wq, wq_set, wql);
wqs_unlock(wq_set);
wait_queue_unlock(wq);
splx(s);
kfree((vm_offset_t)wql, sizeof(struct wait_queue_link));
return KERN_SUCCESS;
}
}
wq_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
}
wait_queue_unlock(wq);
splx(s);
return KERN_NOT_IN_SET;
}
/*
* Routine: wait_queue_unlink_one
* Purpose:
* Find and unlink one set wait queue
* Conditions:
* Nothing of interest locked.
*/
void
wait_queue_unlink_one(
wait_queue_t wq,
wait_queue_set_t *wq_setp)
{
wait_queue_element_t wq_element;
queue_t q;
spl_t s;
s = splsched();
wait_queue_lock(wq);
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_set_t wq_set = wql->wql_setqueue;
wqs_lock(wq_set);
wait_queue_unlink_locked(wq, wq_set, wql);
wqs_unlock(wq_set);
wait_queue_unlock(wq);
splx(s);
kfree((vm_offset_t)wql,sizeof(struct wait_queue_link));
*wq_setp = wq_set;
return;
}
wq_element = (wait_queue_element_t)
queue_next((queue_t) wq_element);
}
wait_queue_unlock(wq);
splx(s);
*wq_setp = WAIT_QUEUE_SET_NULL;
}
/*
* Routine: wait_queue_peek64_locked
* Purpose:
* Select the best thread from a wait queue that meet the
* supplied criteria, but leave it on the queue it was
* found on. The thread, and the actual wait_queue the
* thread was found on are identified.
* Conditions:
* at splsched
* wait queue locked
* possibly recursive
* Returns:
* a locked thread - if one found
* a locked waitq - the one the thread was found on
* Note:
* Both the waitq the thread was actually found on, and
* the supplied wait queue, are locked after this.
*/
__private_extern__ void
wait_queue_peek64_locked(
wait_queue_t wq,
event64_t event,
thread_t *tp,
wait_queue_t *wqp)
{
wait_queue_element_t wq_element;
wait_queue_element_t wqe_next;
thread_t t;
queue_t q;
assert(wq->wq_fifo);
*tp = THREAD_NULL;
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wqe_next = (wait_queue_element_t)
queue_next((queue_t) wq_element);
/*
* We may have to recurse if this is a compound wait queue.
*/
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_t set_queue;
/*
* We have to check the set wait queue.
*/
set_queue = (wait_queue_t)wql->wql_setqueue;
wait_queue_lock(set_queue);
if (! wait_queue_empty(set_queue)) {
wait_queue_peek64_locked(set_queue, event, tp, wqp);
}
if (*tp != THREAD_NULL) {
if (*wqp != set_queue)
wait_queue_unlock(set_queue);
return; /* thread and its waitq locked */
}
wait_queue_unlock(set_queue);
} else {
/*
* Otherwise, its a thread. If it is waiting on
* the event we are posting to this queue, return
* it locked, but leave it on the queue.
*/
thread_t t = (thread_t)wq_element;
if (t->wait_event == event) {
thread_lock(t);
*tp = t;
*wqp = wq;
return;
}
}
wq_element = wqe_next;
}
}
/*
* ROUTINE: ulock_release_internal [internal]
*
* Releases the ulock.
* If any threads are blocked waiting for the ulock, one is woken-up.
*
*/
kern_return_t
ulock_release_internal (ulock_t ulock, thread_t thread)
{
lock_set_t lock_set;
if ((lock_set = ulock->lock_set) == LOCK_SET_NULL)
return KERN_INVALID_ARGUMENT;
lock_set_lock(lock_set);
if (!lock_set->active) {
lock_set_unlock(lock_set);
return KERN_LOCK_SET_DESTROYED;
}
ulock_lock(ulock);
lock_set_unlock(lock_set);
if (ulock->holder != thread) {
ulock_unlock(ulock);
return KERN_INVALID_RIGHT;
}
/*
* If we have a hint that threads might be waiting,
* try to transfer the lock ownership to a waiting thread
* and wake it up.
*/
if (ulock->blocked) {
wait_queue_t wq = &ulock->wait_queue;
thread_t wqthread;
spl_t s;
s = splsched();
wait_queue_lock(wq);
wqthread = wait_queue_wakeup64_identity_locked(wq,
LOCK_SET_EVENT,
THREAD_AWAKENED,
TRUE);
/* wait_queue now unlocked, thread locked */
if (wqthread != THREAD_NULL) {
thread_unlock(wqthread);
splx(s);
/*
* Transfer ulock ownership
* from the current thread to the acquisition thread.
*/
ulock_ownership_clear(ulock);
ulock_ownership_set(ulock, wqthread);
ulock_unlock(ulock);
return KERN_SUCCESS;
} else {
ulock->blocked = FALSE;
splx(s);
}
}
/*
* Disown ulock
*/
ulock_ownership_clear(ulock);
ulock_unlock(ulock);
return KERN_SUCCESS;
}
/*
* Routine: _wait_queue_select64_all
* Purpose:
* Select all threads off a wait queue that meet the
* supplied criteria.
* Conditions:
* at splsched
* wait queue locked
* wake_queue initialized and ready for insertion
* possibly recursive
* Returns:
* a queue of locked threads
*/
static void
_wait_queue_select64_all(
wait_queue_t wq,
event64_t event,
queue_t wake_queue)
{
wait_queue_element_t wq_element;
wait_queue_element_t wqe_next;
queue_t q;
q = &wq->wq_queue;
wq_element = (wait_queue_element_t) queue_first(q);
while (!queue_end(q, (queue_entry_t)wq_element)) {
WAIT_QUEUE_ELEMENT_CHECK(wq, wq_element);
wqe_next = (wait_queue_element_t)
queue_next((queue_t) wq_element);
/*
* We may have to recurse if this is a compound wait queue.
*/
if (wq_element->wqe_type == WAIT_QUEUE_LINK) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_t set_queue;
/*
* We have to check the set wait queue.
*/
set_queue = (wait_queue_t)wql->wql_setqueue;
wait_queue_lock(set_queue);
if (set_queue->wq_isprepost) {
wait_queue_set_t wqs = (wait_queue_set_t)set_queue;
/*
* Preposting is only for sets and wait queue
* is the first element of set
*/
wqs->wqs_refcount++;
}
if (! wait_queue_empty(set_queue))
_wait_queue_select64_all(set_queue, event, wake_queue);
wait_queue_unlock(set_queue);
} else {
/*
* Otherwise, its a thread. If it is waiting on
* the event we are posting to this queue, pull
* it off the queue and stick it in out wake_queue.
*/
thread_t t = (thread_t)wq_element;
if (t->wait_event == event) {
thread_lock(t);
remqueue(q, (queue_entry_t) t);
enqueue (wake_queue, (queue_entry_t) t);
t->wait_queue = WAIT_QUEUE_NULL;
t->wait_event = NO_EVENT64;
t->at_safe_point = FALSE;
/* returned locked */
}
}
wq_element = wqe_next;
}
}
/*
* ROUTINE: ulock_release_internal [internal]
*
* Releases the ulock.
* If any threads are blocked waiting for the ulock, one is woken-up.
*
*/
kern_return_t
ulock_release_internal (ulock_t ulock, thread_t thread)
{
lock_set_t lock_set;
if ((lock_set = ulock->lock_set) == LOCK_SET_NULL)
return KERN_INVALID_ARGUMENT;
lock_set_lock(lock_set);
if (!lock_set->active) {
lock_set_unlock(lock_set);
return KERN_LOCK_SET_DESTROYED;
}
ulock_lock(ulock);
lock_set_unlock(lock_set);
if (ulock->holder != thread) {
ulock_unlock(ulock);
return KERN_INVALID_RIGHT;
}
/*
* If we have a hint that threads might be waiting,
* try to transfer the lock ownership to a waiting thread
* and wake it up.
*/
if (ulock->blocked) {
wait_queue_t wq = &ulock->wait_queue;
thread_t wqthread;
spl_t s;
s = splsched();
wait_queue_lock(wq);
wqthread = wait_queue_wakeup64_identity_locked(wq,
LOCK_SET_EVENT,
THREAD_AWAKENED,
TRUE);
/* wait_queue now unlocked, thread locked */
if (wqthread != THREAD_NULL) {
/*
* JMM - These ownership transfer macros have a
* locking/race problem. To keep the thread from
* changing states on us (nullifying the ownership
* assignment) we need to keep the thread locked
* during the assignment. But we can't because the
* macros take an activation lock, which is a mutex.
* Since this code was already broken before I got
* here, I will leave it for now.
*/
thread_unlock(wqthread);
splx(s);
/*
* Transfer ulock ownership
* from the current thread to the acquisition thread.
*/
ulock_ownership_clear(ulock);
ulock_ownership_set(ulock, wqthread);
ulock_unlock(ulock);
return KERN_SUCCESS;
} else {
ulock->blocked = FALSE;
splx(s);
}
}
/*
* Disown ulock
*/
ulock_ownership_clear(ulock);
ulock_unlock(ulock);
return KERN_SUCCESS;
}
kern_return_t
lock_handoff (lock_set_t lock_set, int lock_id)
{
ulock_t ulock;
int wait_result;
if (lock_set == LOCK_SET_NULL)
return KERN_INVALID_ARGUMENT;
if (lock_id < 0 || lock_id >= lock_set->n_ulocks)
return KERN_INVALID_ARGUMENT;
retry:
lock_set_lock(lock_set);
if (!lock_set->active) {
lock_set_unlock(lock_set);
return KERN_LOCK_SET_DESTROYED;
}
ulock = (ulock_t) &lock_set->ulock_list[lock_id];
ulock_lock(ulock);
lock_set_unlock(lock_set);
if (ulock->holder != current_thread()) {
ulock_unlock(ulock);
return KERN_INVALID_RIGHT;
}
/*
* If the accepting thread (the receiver) is already waiting
* to accept the lock from the handoff thread (the sender),
* then perform the hand-off now.
*/
if (ulock->accept_wait) {
wait_queue_t wq = &ulock->wait_queue;
thread_t thread;
spl_t s;
/*
* See who the lucky devil is, if he is still there waiting.
*/
s = splsched();
wait_queue_lock(wq);
thread = wait_queue_wakeup64_identity_locked(
wq,
LOCK_SET_HANDOFF,
THREAD_AWAKENED,
TRUE);
/* wait queue unlocked, thread locked */
/*
* Transfer lock ownership
*/
if (thread != THREAD_NULL) {
/*
* The thread we are transferring to will try
* to take the lock on the ulock, and therefore
* will wait for us complete the handoff even
* through we set the thread running.
*/
thread_unlock(thread);
splx(s);
ulock_ownership_clear(ulock);
ulock_ownership_set(ulock, thread);
ulock->accept_wait = FALSE;
ulock_unlock(ulock);
return KERN_SUCCESS;
} else {
/*
* OOPS. The accepting thread must have been aborted.
* and is racing back to clear the flag that says is
* waiting for an accept. He will clear it when we
* release the lock, so just fall thru and wait for
* the next accept thread (that's the way it is
* specified).
*/
splx(s);
}
}
/*
* Indicate that there is a hand-off thread waiting, and then wait
* for an accepting thread.
*/
ulock->ho_wait = TRUE;
wait_result = wait_queue_assert_wait64(&ulock->wait_queue,
LOCK_SET_HANDOFF,
THREAD_ABORTSAFE, 0);
ulock_unlock(ulock);
if (wait_result == THREAD_WAITING)
wait_result = thread_block(THREAD_CONTINUE_NULL);
/*
* If the thread was woken-up via some action other than
* lock_handoff_accept or lock_set_destroy (i.e. thread_terminate),
* then we need to clear the ulock's handoff state.
*/
switch (wait_result) {
case THREAD_AWAKENED:
/*
* we take the ulock lock to syncronize with the
* thread that is accepting ownership.
*/
ulock_lock(ulock);
assert(ulock->holder != current_thread());
ulock_unlock(ulock);
return KERN_SUCCESS;
case THREAD_INTERRUPTED:
ulock_lock(ulock);
assert(ulock->holder == current_thread());
ulock->ho_wait = FALSE;
ulock_unlock(ulock);
return KERN_ABORTED;
case THREAD_RESTART:
goto retry;
}
panic("lock_handoff");
return KERN_FAILURE;
}
