void *echo_loop(void *arg) {
echo_t *echo = (echo_t *) arg;
LOG("\nEnter echo loop !\n\n");
while (!thread_is_interrupted(echo->thread)) {
LOG("echo %d\n", echo->num++);
sleep(1);
}
LOG("\nLeave echo loop !\n\n");
}
status_t
switch_sem_etc(sem_id semToBeReleased, sem_id id, int32 count,
uint32 flags, bigtime_t timeout)
{
int slot = id % sMaxSems;
int state;
status_t status = B_OK;
if (gKernelStartup)
return B_OK;
if (sSemsActive == false)
return B_NO_MORE_SEMS;
if (!are_interrupts_enabled()) {
panic("switch_sem_etc: called with interrupts disabled for sem %ld\n",
id);
}
if (id < 0)
return B_BAD_SEM_ID;
if (count <= 0
|| (flags & (B_RELATIVE_TIMEOUT | B_ABSOLUTE_TIMEOUT)) == (B_RELATIVE_TIMEOUT | B_ABSOLUTE_TIMEOUT)) {
return B_BAD_VALUE;
}
state = disable_interrupts();
GRAB_SEM_LOCK(sSems[slot]);
if (sSems[slot].id != id) {
TRACE(("switch_sem_etc: bad sem %ld\n", id));
status = B_BAD_SEM_ID;
goto err;
}
// TODO: the B_CHECK_PERMISSION flag should be made private, as it
// doesn't have any use outside the kernel
if ((flags & B_CHECK_PERMISSION) != 0
&& sSems[slot].u.used.owner == team_get_kernel_team_id()) {
dprintf("thread %ld tried to acquire kernel semaphore %ld.\n",
thread_get_current_thread_id(), id);
status = B_NOT_ALLOWED;
goto err;
}
if (sSems[slot].u.used.count - count < 0) {
if ((flags & B_RELATIVE_TIMEOUT) != 0 && timeout <= 0) {
// immediate timeout
status = B_WOULD_BLOCK;
goto err;
} else if ((flags & B_ABSOLUTE_TIMEOUT) != 0 && timeout < 0) {
// absolute negative timeout
status = B_TIMED_OUT;
goto err;
}
}
KTRACE("switch_sem_etc(semToBeReleased: %ld, sem: %ld, count: %ld, "
"flags: 0x%lx, timeout: %lld)", semToBeReleased, id, count, flags,
timeout);
if ((sSems[slot].u.used.count -= count) < 0) {
// we need to block
Thread *thread = thread_get_current_thread();
TRACE(("switch_sem_etc(id = %ld): block name = %s, thread = %p,"
" name = %s\n", id, sSems[slot].u.used.name, thread, thread->name));
// do a quick check to see if the thread has any pending signals
// this should catch most of the cases where the thread had a signal
SpinLocker schedulerLocker(gSchedulerLock);
if (thread_is_interrupted(thread, flags)) {
schedulerLocker.Unlock();
sSems[slot].u.used.count += count;
status = B_INTERRUPTED;
// the other semaphore will be released later
goto err;
}
if ((flags & (B_RELATIVE_TIMEOUT | B_ABSOLUTE_TIMEOUT)) == 0)
timeout = B_INFINITE_TIMEOUT;
// enqueue in the semaphore queue and get ready to wait
queued_thread queueEntry(thread, count);
sSems[slot].queue.Add(&queueEntry);
queueEntry.queued = true;
thread_prepare_to_block(thread, flags, THREAD_BLOCK_TYPE_SEMAPHORE,
(void*)(addr_t)id);
RELEASE_SEM_LOCK(sSems[slot]);
// release the other semaphore, if any
if (semToBeReleased >= 0) {
release_sem_etc(semToBeReleased, 1, B_DO_NOT_RESCHEDULE);
semToBeReleased = -1;
}
schedulerLocker.Lock();
status_t acquireStatus = timeout == B_INFINITE_TIMEOUT
? thread_block_locked(thread)
: thread_block_with_timeout_locked(flags, timeout);
schedulerLocker.Unlock();
GRAB_SEM_LOCK(sSems[slot]);
// If we're still queued, this means the acquiration failed, and we
// need to remove our entry and (potentially) wake up other threads.
if (queueEntry.queued)
remove_thread_from_sem(&queueEntry, &sSems[slot]);
if (acquireStatus >= B_OK) {
sSems[slot].u.used.last_acquirer = thread_get_current_thread_id();
#if DEBUG_SEM_LAST_ACQUIRER
sSems[slot].u.used.last_acquire_count = count;
#endif
}
RELEASE_SEM_LOCK(sSems[slot]);
restore_interrupts(state);
TRACE(("switch_sem_etc(sem %ld): exit block name %s, "
"thread %ld (%s)\n", id, sSems[slot].u.used.name, thread->id,
thread->name));
KTRACE("switch_sem_etc() done: 0x%lx", acquireStatus);
return acquireStatus;
} else {
sSems[slot].u.used.net_count -= count;
sSems[slot].u.used.last_acquirer = thread_get_current_thread_id();
#if DEBUG_SEM_LAST_ACQUIRER
sSems[slot].u.used.last_acquire_count = count;
#endif
}
err:
RELEASE_SEM_LOCK(sSems[slot]);
restore_interrupts(state);
if (status == B_INTERRUPTED && semToBeReleased >= B_OK) {
// depending on when we were interrupted, we need to still
// release the semaphore to always leave in a consistent
// state
release_sem_etc(semToBeReleased, 1, B_DO_NOT_RESCHEDULE);
}
#if 0
if (status == B_NOT_ALLOWED)
_user_debugger("Thread tried to acquire kernel semaphore.");
#endif
KTRACE("switch_sem_etc() done: 0x%lx", status);
return status;
}
