clear_bit — Clears a bit in memory
void clear_bit ( | long nr, |
volatile unsigned long * addr); |
clear_bit is atomic and may not be reordered. However, it does
not contain a memory barrier, so if it is used for locking purposes,
you should call smp_mb__before_atomic and/or smp_mb__after_atomic
in order to ensure changes are visible on other processors.