/*
* Routine: ipc_mqueue_select_on_thread
* Purpose:
* A receiver discovered that there was a message on the queue
* before he had to block. Pick the message off the queue and
* "post" it to thread.
* Conditions:
* mqueue locked.
* thread not locked.
* There is a message.
* Returns:
* MACH_MSG_SUCCESS Actually selected a message for ourselves.
* MACH_RCV_TOO_LARGE May or may not have pull it, but it is large
*/
void
ipc_mqueue_select_on_thread(
ipc_mqueue_t mqueue,
mach_msg_option_t option,
mach_msg_size_t max_size,
thread_t thread)
{
ipc_kmsg_t kmsg;
mach_msg_return_t mr = MACH_MSG_SUCCESS;
mach_msg_size_t rcv_size;
/*
* Do some sanity checking of our ability to receive
* before pulling the message off the queue.
*/
kmsg = ipc_kmsg_queue_first(&mqueue->imq_messages);
assert(kmsg != IKM_NULL);
/*
* If we really can't receive it, but we had the
* MACH_RCV_LARGE option set, then don't take it off
* the queue, instead return the appropriate error
* (and size needed).
*/
rcv_size = ipc_kmsg_copyout_size(kmsg, thread->map);
if (rcv_size + REQUESTED_TRAILER_SIZE(thread_is_64bit(thread), option) > max_size) {
mr = MACH_RCV_TOO_LARGE;
if (option & MACH_RCV_LARGE) {
thread->ith_receiver_name = mqueue->imq_receiver_name;
thread->ith_kmsg = IKM_NULL;
thread->ith_msize = rcv_size;
thread->ith_seqno = 0;
thread->ith_state = mr;
return;
}
}
ipc_kmsg_rmqueue_first_macro(&mqueue->imq_messages, kmsg);
ipc_mqueue_release_msgcount(mqueue);
thread->ith_seqno = mqueue->imq_seqno++;
thread->ith_kmsg = kmsg;
thread->ith_state = mr;
current_task()->messages_received++;
return;
}
/* flipc_port_destroy() is called to convert a flipc port back to a
* local-only ipc port (i.e., the port has no remaining off-node rights).
* This will dispose of any undelivered flipc messages, generating NAKs if
* needed. <lport> must be locked on entry and is not unlocked on return.
*/
static void
flipc_port_destroy(ipc_port_t lport)
{
/* Ensure parameter is valid, and linked to an fport with a valid name */
assert(IP_VALID(lport));
ipc_mqueue_t port_mq = &lport->ip_messages;
flipc_port_t fport = port_mq->data.port.fport;
assert(FPORT_VALID(fport));
assert(MNL_NAME_VALID(fport->obj.name));
/* Dispose of any undelivered messages */
int m = port_mq->data.port.msgcount;
if (m > 0) {
ipc_kmsg_t kmsg;
#ifdef DEBUG
printf("flipc: destroying %p with %d undelivered msgs\n", lport, m);
#endif
/* Logic was lifted from ipc_mqueue_select_on_thread() */
while (m--) {
kmsg = ipc_kmsg_queue_first(&port_mq->imq_messages);
assert(kmsg != IKM_NULL);
ipc_kmsg_rmqueue(&port_mq->imq_messages, kmsg);
if (fport->state == FPORT_STATE_PRINCIPAL)
flipc_msg_ack(kmsg->ikm_node, port_mq, FALSE);
ipc_mqueue_release_msgcount(port_mq, NULL);
port_mq->imq_seqno++;
}
}
/* Remove from name hash table, unlink co-structures, and free fport */
mnl_obj_remove(fport->obj.name);
lport->ip_messages.data.port.fport = FPORT_NULL;
fport->lport = IP_NULL;
zfree(flipc_port_zone, fport);
}
/*
* Routine: ipc_mqueue_post
* Purpose:
* Post a message to a waiting receiver or enqueue it. If a
* receiver is waiting, we can release our reserved space in
* the message queue.
*
* Conditions:
* If we need to queue, our space in the message queue is reserved.
*/
void
ipc_mqueue_post(
register ipc_mqueue_t mqueue,
register ipc_kmsg_t kmsg)
{
spl_t s;
/*
* While the msg queue is locked, we have control of the
* kmsg, so the ref in it for the port is still good.
*
* Check for a receiver for the message.
*/
s = splsched();
imq_lock(mqueue);
for (;;) {
wait_queue_t waitq = &mqueue->imq_wait_queue;
thread_t receiver;
mach_msg_size_t msize;
receiver = wait_queue_wakeup64_identity_locked(
waitq,
IPC_MQUEUE_RECEIVE,
THREAD_AWAKENED,
FALSE);
/* waitq still locked, thread locked */
if (receiver == THREAD_NULL) {
/*
* no receivers; queue kmsg
*/
assert(mqueue->imq_msgcount > 0);
ipc_kmsg_enqueue_macro(&mqueue->imq_messages, kmsg);
break;
}
/*
* If the receiver waited with a facility not directly
* related to Mach messaging, then it isn't prepared to get
* handed the message directly. Just set it running, and
* go look for another thread that can.
*/
if (receiver->ith_state != MACH_RCV_IN_PROGRESS) {
thread_unlock(receiver);
continue;
}
/*
* We found a waiting thread.
* If the message is too large or the scatter list is too small
* the thread we wake up will get that as its status.
*/
msize = ipc_kmsg_copyout_size(kmsg, receiver->map);
if (receiver->ith_msize <
(msize + REQUESTED_TRAILER_SIZE(thread_is_64bit(receiver), receiver->ith_option))) {
receiver->ith_msize = msize;
receiver->ith_state = MACH_RCV_TOO_LARGE;
} else {
receiver->ith_state = MACH_MSG_SUCCESS;
}
/*
* If there is no problem with the upcoming receive, or the
* receiver thread didn't specifically ask for special too
* large error condition, go ahead and select it anyway.
*/
if ((receiver->ith_state == MACH_MSG_SUCCESS) ||
!(receiver->ith_option & MACH_RCV_LARGE)) {
receiver->ith_kmsg = kmsg;
receiver->ith_seqno = mqueue->imq_seqno++;
thread_unlock(receiver);
/* we didn't need our reserved spot in the queue */
ipc_mqueue_release_msgcount(mqueue);
break;
}
/*
* Otherwise, this thread needs to be released to run
* and handle its error without getting the message. We
* need to go back and pick another one.
*/
receiver->ith_receiver_name = mqueue->imq_receiver_name;
receiver->ith_kmsg = IKM_NULL;
receiver->ith_seqno = 0;
thread_unlock(receiver);
}
imq_unlock(mqueue);
splx(s);
current_task()->messages_sent++;
return;
}
/*
* Routine: ipc_mqueue_add
* Purpose:
* Associate the portset's mqueue with the port's mqueue.
* This has to be done so that posting the port will wakeup
* a portset waiter. If there are waiters on the portset
* mqueue and messages on the port mqueue, try to match them
* up now.
* Conditions:
* May block.
*/
kern_return_t
ipc_mqueue_add(
ipc_mqueue_t port_mqueue,
ipc_mqueue_t set_mqueue,
wait_queue_link_t wql)
{
wait_queue_t port_waitq = &port_mqueue->imq_wait_queue;
wait_queue_set_t set_waitq = &set_mqueue->imq_set_queue;
ipc_kmsg_queue_t kmsgq;
ipc_kmsg_t kmsg, next;
kern_return_t kr;
spl_t s;
kr = wait_queue_link_noalloc(port_waitq, set_waitq, wql);
if (kr != KERN_SUCCESS)
return kr;
/*
* Now that the set has been added to the port, there may be
* messages queued on the port and threads waiting on the set
* waitq. Lets get them together.
*/
s = splsched();
imq_lock(port_mqueue);
kmsgq = &port_mqueue->imq_messages;
for (kmsg = ipc_kmsg_queue_first(kmsgq);
kmsg != IKM_NULL;
kmsg = next) {
next = ipc_kmsg_queue_next(kmsgq, kmsg);
for (;;) {
thread_t th;
mach_msg_size_t msize;
th = wait_queue_wakeup64_identity_locked(
port_waitq,
IPC_MQUEUE_RECEIVE,
THREAD_AWAKENED,
FALSE);
/* waitq/mqueue still locked, thread locked */
if (th == THREAD_NULL)
goto leave;
/*
* If the receiver waited with a facility not directly
* related to Mach messaging, then it isn't prepared to get
* handed the message directly. Just set it running, and
* go look for another thread that can.
*/
if (th->ith_state != MACH_RCV_IN_PROGRESS) {
thread_unlock(th);
continue;
}
/*
* Found a receiver. see if they can handle the message
* correctly (the message is not too large for them, or
* they didn't care to be informed that the message was
* too large). If they can't handle it, take them off
* the list and let them go back and figure it out and
* just move onto the next.
*/
msize = ipc_kmsg_copyout_size(kmsg, th->map);
if (th->ith_msize <
(msize + REQUESTED_TRAILER_SIZE(thread_is_64bit(th), th->ith_option))) {
th->ith_state = MACH_RCV_TOO_LARGE;
th->ith_msize = msize;
if (th->ith_option & MACH_RCV_LARGE) {
/*
* let him go without message
*/
th->ith_receiver_name = port_mqueue->imq_receiver_name;
th->ith_kmsg = IKM_NULL;
th->ith_seqno = 0;
thread_unlock(th);
continue; /* find another thread */
}
} else {
th->ith_state = MACH_MSG_SUCCESS;
}
/*
* This thread is going to take this message,
* so give it to him.
*/
ipc_kmsg_rmqueue(kmsgq, kmsg);
ipc_mqueue_release_msgcount(port_mqueue);
th->ith_kmsg = kmsg;
th->ith_seqno = port_mqueue->imq_seqno++;
thread_unlock(th);
break; /* go to next message */
}
}
leave:
imq_unlock(port_mqueue);
splx(s);
return KERN_SUCCESS;
}