Function - Increments the semaphore count.
kern_return_t semaphore_signal (semaphore_t semaphore);
The semaphore_signal function increments the semaphore count. If the count goes non-negative (i.e. greater than or equal to 0) and a thread is blocked on the semaphore, then the waiting thread is scheduled to execute. If multiple threads are blocked on the semaphore, the thread scheduled to execute is selected according to the wakeup policy of the semaphore (set when the semaphore was created via semaphore_create). Device driver interrupt service routines may safely execute semaphore_signal operations without causing a deadlock.
Functions: semaphore_create, semaphore_destroy, semaphore_signal_all, semaphore_wait, device_get_status.