wq
condition
The process is put to sleep (TASK_KILLABLE) until the condition evaluates to true or a signal is received. The condition is checked each time the waitqueue wq is woken up.
wake_up has to be called after changing any variable that could change the result of the wait condition.
The function will return -ERESTARTSYS if it was interrupted by a signal and 0 if condition evaluated to true.