static void
alq_shutdown(struct alq *alq)
{
ALQ_LOCK(alq);
/* Stop any new writers. */
alq->aq_flags |= AQ_SHUTDOWN;
/*
* If the ALQ isn't active but has unwritten data (possible if
* the ALQ_NOACTIVATE flag has been used), explicitly activate the
* ALQ here so that the pending data gets flushed by the ald_daemon.
*/
if (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq)) {
alq->aq_flags |= AQ_ACTIVE;
ALQ_UNLOCK(alq);
ALD_LOCK();
ald_activate(alq);
ALD_UNLOCK();
ALQ_LOCK(alq);
}
/* Drain IO */
while (alq->aq_flags & AQ_ACTIVE) {
alq->aq_flags |= AQ_WANTED;
msleep_spin(alq, &alq->aq_mtx, "aldclose", 0);
}
ALQ_UNLOCK(alq);
vn_close(alq->aq_vp, FWRITE, alq->aq_cred,
curthread);
crfree(alq->aq_cred);
}
void
alq_post_flags(struct alq *alq, struct ale *ale, int flags)
{
int activate;
void *waitchan;
activate = 0;
if (ale->ae_bytesused > 0) {
if (!(alq->aq_flags & AQ_ACTIVE) &&
!(flags & ALQ_NOACTIVATE)) {
alq->aq_flags |= AQ_ACTIVE;
activate = 1;
}
alq->aq_writehead += ale->ae_bytesused;
alq->aq_freebytes -= ale->ae_bytesused;
/* Wrap aq_writehead if we filled to the end of the buffer. */
if (alq->aq_writehead == alq->aq_buflen)
alq->aq_writehead = 0;
KASSERT((alq->aq_writehead >= 0 &&
alq->aq_writehead < alq->aq_buflen),
("%s: aq_writehead < 0 || aq_writehead >= aq_buflen",
__func__));
KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));
}
/*
* If there are waiters, we need to signal the waiting threads after we
* complete our work. The alq ptr is used as a wait channel for threads
* requiring resources to be freed up. In the AQ_ORDERED case, threads
* are not allowed to concurrently compete for resources in the
* alq_getn() while loop, so we use a different wait channel in this case.
*/
if (alq->aq_waiters > 0) {
if (alq->aq_flags & AQ_ORDERED)
waitchan = &alq->aq_waiters;
else
waitchan = alq;
} else
waitchan = NULL;
ALQ_UNLOCK(alq);
if (activate) {
ALD_LOCK();
ald_activate(alq);
ALD_UNLOCK();
}
/* NB: We rely on wakeup_one waking threads in a FIFO manner. */
if (waitchan != NULL)
wakeup_one(waitchan);
}
void
alq_post(struct alq *alq, struct ale *ale)
{
int activate;
ale->ae_flags |= AE_VALID;
if (alq->aq_entvalid == NULL)
alq->aq_entvalid = ale;
if ((alq->aq_flags & AQ_ACTIVE) == 0) {
alq->aq_flags |= AQ_ACTIVE;
activate = 1;
} else
activate = 0;
spin_unlock(&alq->aq_lock);
if (activate) {
ALD_LOCK();
ald_activate(alq);
ALD_UNLOCK();
}
}
/*
* Copy a new entry into the queue. If the operation would block either
* wait or return an error depending on the value of waitok.
*/
int
alq_writen(struct alq *alq, void *data, int len, int flags)
{
int activate, copy, ret;
void *waitchan;
KASSERT((len > 0 && len <= alq->aq_buflen),
("%s: len <= 0 || len > aq_buflen", __func__));
activate = ret = 0;
copy = len;
waitchan = NULL;
ALQ_LOCK(alq);
/*
* Fail to perform the write and return EWOULDBLOCK if:
* - The message is larger than our underlying buffer.
* - The ALQ is being shutdown.
* - There is insufficient free space in our underlying buffer
* to accept the message and the user can't wait for space.
* - There is insufficient free space in our underlying buffer
* to accept the message and the alq is inactive due to prior
* use of the ALQ_NOACTIVATE flag (which would lead to deadlock).
*/
if (len > alq->aq_buflen ||
alq->aq_flags & AQ_SHUTDOWN ||
(((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) &&
HAS_PENDING_DATA(alq))) && alq->aq_freebytes < len)) {
ALQ_UNLOCK(alq);
return (EWOULDBLOCK);
}
/*
* If we want ordered writes and there is already at least one thread
* waiting for resources to become available, sleep until we're woken.
*/
if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) {
KASSERT(!(flags & ALQ_NOWAIT),
("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
alq->aq_waiters++;
msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqwnord", 0);
alq->aq_waiters--;
}
/*
* (ALQ_WAITOK && aq_freebytes < len) or aq_freebytes >= len, either
* enter while loop and sleep until we have enough free bytes (former)
* or skip (latter). If AQ_ORDERED is set, only 1 thread at a time will
* be in this loop. Otherwise, multiple threads may be sleeping here
* competing for ALQ resources.
*/
while (alq->aq_freebytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) {
KASSERT(!(flags & ALQ_NOWAIT),
("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
alq->aq_flags |= AQ_WANTED;
alq->aq_waiters++;
if (waitchan)
wakeup(waitchan);
msleep_spin(alq, &alq->aq_mtx, "alqwnres", 0);
alq->aq_waiters--;
/*
* If we're the first thread to wake after an AQ_WANTED wakeup
* but there isn't enough free space for us, we're going to loop
* and sleep again. If there are other threads waiting in this
* loop, schedule a wakeup so that they can see if the space
* they require is available.
*/
if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) &&
alq->aq_freebytes < len && !(alq->aq_flags & AQ_WANTED))
waitchan = alq;
else
waitchan = NULL;
}
/*
* If there are waiters, we need to signal the waiting threads after we
* complete our work. The alq ptr is used as a wait channel for threads
* requiring resources to be freed up. In the AQ_ORDERED case, threads
* are not allowed to concurrently compete for resources in the above
* while loop, so we use a different wait channel in this case.
*/
if (alq->aq_waiters > 0) {
if (alq->aq_flags & AQ_ORDERED)
waitchan = &alq->aq_waiters;
else
waitchan = alq;
} else
waitchan = NULL;
/* Bail if we're shutting down. */
if (alq->aq_flags & AQ_SHUTDOWN) {
ret = EWOULDBLOCK;
goto unlock;
}
/*
* If we need to wrap the buffer to accommodate the write,
* we'll need 2 calls to bcopy.
*/
if ((alq->aq_buflen - alq->aq_writehead) < len)
copy = alq->aq_buflen - alq->aq_writehead;
/* Copy message (or part thereof if wrap required) to the buffer. */
bcopy(data, alq->aq_entbuf + alq->aq_writehead, copy);
alq->aq_writehead += copy;
if (alq->aq_writehead >= alq->aq_buflen) {
KASSERT((alq->aq_writehead == alq->aq_buflen),
("%s: alq->aq_writehead (%d) > alq->aq_buflen (%d)",
__func__,
alq->aq_writehead,
alq->aq_buflen));
alq->aq_writehead = 0;
}
if (copy != len) {
/*
* Wrap the buffer by copying the remainder of our message
* to the start of the buffer and resetting aq_writehead.
*/
bcopy(((uint8_t *)data)+copy, alq->aq_entbuf, len - copy);
alq->aq_writehead = len - copy;
}
KASSERT((alq->aq_writehead >= 0 && alq->aq_writehead < alq->aq_buflen),
("%s: aq_writehead < 0 || aq_writehead >= aq_buflen", __func__));
alq->aq_freebytes -= len;
if (!(alq->aq_flags & AQ_ACTIVE) && !(flags & ALQ_NOACTIVATE)) {
alq->aq_flags |= AQ_ACTIVE;
activate = 1;
}
KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));
unlock:
ALQ_UNLOCK(alq);
if (activate) {
ALD_LOCK();
ald_activate(alq);
ALD_UNLOCK();
}
/* NB: We rely on wakeup_one waking threads in a FIFO manner. */
if (waitchan != NULL)
wakeup_one(waitchan);
return (ret);
}
