CLEAR_BIT(9) Basic C Library Functions CLEAR_BIT(9)
NAME clear_bit - Clears a bit in memory
SYNOPSIS void clear_bit(int nr, volatile unsigned long * addr);
ARGUMENTS nr Bit to clear
addr Address to start counting from
DESCRIPTION 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_clear_bit and/or smp_mb__after_clear_bit in order to ensure changes are visible on other processors.
COPYRIGHT Kernel Hackers Manual 2.6. November 2011 CLEAR_BIT(9)