/*
* Routine: wait_queue_unlink_locked
* Purpose:
* Undo the linkage between a wait queue and a set.
*/
static void
wait_queue_unlink_locked(
wait_queue_t wq,
wait_queue_set_t wq_set,
wait_queue_link_t wql)
{
assert(wait_queue_held(wq));
assert(wait_queue_held(&wq_set->wqs_wait_queue));
wql->wql_queue = WAIT_QUEUE_NULL;
queue_remove(&wq->wq_queue, wql, wait_queue_link_t, wql_links);
wql->wql_setqueue = WAIT_QUEUE_SET_NULL;
queue_remove(&wq_set->wqs_setlinks, wql, wait_queue_link_t, wql_setlinks);
if (wql_is_preposted(wql)) {
queue_t ppq = &wq_set->wqs_preposts;
queue_remove(ppq, wql, wait_queue_link_t, wql_preposts);
}
wql->wql_type = WAIT_QUEUE_UNLINKED;
WAIT_QUEUE_CHECK(wq);
WAIT_QUEUE_SET_CHECK(wq_set);
}
kern_return_t
wait_queue_sub_clearrefs(
wait_queue_set_t wq_set)
{
wait_queue_link_t wql;
queue_t q;
spl_t s;
if (!wait_queue_is_set(wq_set))
return KERN_INVALID_ARGUMENT;
s = splsched();
wqs_lock(wq_set);
q = &wq_set->wqs_preposts;
while (!queue_empty(q)) {
queue_remove_first(q, wql, wait_queue_link_t, wql_preposts);
assert(!wql_is_preposted(wql));
}
wqs_unlock(wq_set);
splx(s);
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 ||
wq_element->wqe_type == WAIT_QUEUE_LINK_NOALLOC) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_set_t set_queue = wql->wql_setqueue;
/*
* We have to check the set wait queue. If it is marked
* as pre-post, and it is the "generic event" then mark
* it pre-posted now (if not already).
*/
wqs_lock(set_queue);
if (event == NO_EVENT64 && set_queue->wqs_prepost && !wql_is_preposted(wql)) {
queue_t ppq = &set_queue->wqs_preposts;
queue_enter(ppq, wql, wait_queue_link_t, wql_preposts);
}
if (! wait_queue_empty(&set_queue->wqs_wait_queue))
_wait_queue_select64_all(&set_queue->wqs_wait_queue, event, wake_queue);
wqs_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((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: _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/LIFO.
*/
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;
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 ||
wq_element->wqe_type == WAIT_QUEUE_LINK_NOALLOC) {
wait_queue_link_t wql = (wait_queue_link_t)wq_element;
wait_queue_set_t set_queue = wql->wql_setqueue;
/*
* We have to check the set wait queue. If the set
* supports pre-posting, it isn't already preposted,
* and we didn't find a thread in the set, then mark it.
*
* If we later find a thread, there may be a spurious
* pre-post here on this set. The wait side has to check
* for that either pre- or post-wait.
*/
wqs_lock(set_queue);
if (! wait_queue_empty(&set_queue->wqs_wait_queue)) {
t = _wait_queue_select64_one(&set_queue->wqs_wait_queue, event);
}
if (t != THREAD_NULL) {
wqs_unlock(set_queue);
return t;
}
if (event == NO_EVENT64 && set_queue->wqs_prepost && !wql_is_preposted(wql)) {
queue_t ppq = &set_queue->wqs_preposts;
queue_enter(ppq, wql, wait_queue_link_t, wql_preposts);
}
wqs_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.
*/
t = (thread_t)wq_element;
if (t->wait_event == event) {
thread_lock(t);
remqueue((queue_entry_t) t);
t->wait_queue = WAIT_QUEUE_NULL;
t->wait_event = NO_EVENT64;
t->at_safe_point = FALSE;
return t; /* still locked */
}
t = THREAD_NULL;
}
wq_element = wqe_next;
}
return THREAD_NULL;
}
wait_result_t
ipc_mqueue_receive_on_thread(
ipc_mqueue_t mqueue,
mach_msg_option_t option,
mach_msg_size_t max_size,
mach_msg_timeout_t rcv_timeout,
int interruptible,
thread_t thread)
{
ipc_kmsg_queue_t kmsgs;
wait_result_t wresult;
uint64_t deadline;
spl_t s;
s = splsched();
imq_lock(mqueue);
if (imq_is_set(mqueue)) {
queue_t q;
q = &mqueue->imq_preposts;
/*
* If we are waiting on a portset mqueue, we need to see if
* any of the member ports have work for us. Ports that
* have (or recently had) messages will be linked in the
* prepost queue for the portset. By holding the portset's
* mqueue lock during the search, we tie up any attempts by
* mqueue_deliver or portset membership changes that may
* cross our path.
*/
search_set:
while(!queue_empty(q)) {
wait_queue_link_t wql;
ipc_mqueue_t port_mq;
queue_remove_first(q, wql, wait_queue_link_t, wql_preposts);
assert(!wql_is_preposted(wql));
/*
* This is a lock order violation, so we have to do it
* "softly," putting the link back on the prepost list
* if it fails (at the tail is fine since the order of
* handling messages from different sources in a set is
* not guaranteed and we'd like to skip to the next source
* if one is available).
*/
port_mq = (ipc_mqueue_t)wql->wql_queue;
if (!imq_lock_try(port_mq)) {
queue_enter(q, wql, wait_queue_link_t, wql_preposts);
imq_unlock(mqueue);
splx(s);
mutex_pause(0);
s = splsched();
imq_lock(mqueue);
goto search_set; /* start again at beginning - SMP */
}
/*
* If there are no messages on this queue, just skip it
* (we already removed the link from the set's prepost queue).
*/
kmsgs = &port_mq->imq_messages;
if (ipc_kmsg_queue_first(kmsgs) == IKM_NULL) {
imq_unlock(port_mq);
continue;
}
/*
* There are messages, so reinsert the link back
* at the tail of the preposted queue (for fairness)
* while we still have the portset mqueue locked.
*/
queue_enter(q, wql, wait_queue_link_t, wql_preposts);
imq_unlock(mqueue);
/*
* Continue on to handling the message with just
* the port mqueue locked.
*/
ipc_mqueue_select_on_thread(port_mq, option, max_size, thread);
imq_unlock(port_mq);
splx(s);
return THREAD_NOT_WAITING;
}
} else {
/*
* Receive on a single port. Just try to get the messages.
*/
kmsgs = &mqueue->imq_messages;
if (ipc_kmsg_queue_first(kmsgs) != IKM_NULL) {
ipc_mqueue_select_on_thread(mqueue, option, max_size, thread);
imq_unlock(mqueue);
splx(s);
return THREAD_NOT_WAITING;
}
}
/*
* Looks like we'll have to block. The mqueue we will
* block on (whether the set's or the local port's) is
* still locked.
*/
if (option & MACH_RCV_TIMEOUT) {
if (rcv_timeout == 0) {
imq_unlock(mqueue);
splx(s);
thread->ith_state = MACH_RCV_TIMED_OUT;
return THREAD_NOT_WAITING;
}
}
thread_lock(thread);
thread->ith_state = MACH_RCV_IN_PROGRESS;
thread->ith_option = option;
thread->ith_msize = max_size;
if (option & MACH_RCV_TIMEOUT)
clock_interval_to_deadline(rcv_timeout, 1000*NSEC_PER_USEC, &deadline);
else
deadline = 0;
wresult = wait_queue_assert_wait64_locked(&mqueue->imq_wait_queue,
IPC_MQUEUE_RECEIVE,
interruptible,
TIMEOUT_URGENCY_USER_NORMAL,
deadline, 0,
thread);
/* preposts should be detected above, not here */
if (wresult == THREAD_AWAKENED)
panic("ipc_mqueue_receive_on_thread: sleep walking");
thread_unlock(thread);
imq_unlock(mqueue);
splx(s);
return wresult;
}
