Wake up threads blocked on a waitqueue.
void __wake_up(wait_queue_head_t * q, unsigned int mode, int nr_exclusive, void * key);
q
the waitqueue
mode
which threads
nr_exclusive
how many wake-one or wake-many threads to wake up
key
is directly passed to the wakeup function
It may be assumed that this function implies a write memory barrier before changing the task state if and only if any tasks are woken up.