Man page 9 : wait_event_interruptible_lock_irq_cmd

wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true. The condition is checked under the lock. This is expected to be called with the lock taken.

wait_event_interruptible_lock_irq_cmd( wq , condition , lock , cmd );

wq
    the waitqueue to wait on

condition
    a C expression for the event to wait for

lock
    a locked spinlock_t, which will be released before cmd and schedule and reacquired afterwards.

cmd
    a command which is invoked outside the critical section before sleep

The process is put to sleep (TASK_INTERRUPTIBLE) 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.

This is supposed to be called while holding the lock. The lock is dropped before invoking the cmd and going to sleep and is reacquired afterwards.

The macro will return -ERESTARTSYS if it was interrupted by a signal and 0 if condition evaluated to true.