suse man page for set_bit

SET_BIT(9)						     Basic C Library Functions							SET_BIT(9)

NAME
       set_bit - Atomically set a bit in memory

SYNOPSIS
       void set_bit(unsigned int nr, volatile unsigned long * addr);

ARGUMENTS
       nr
	   the bit to set

       addr
	   the address to start counting from

DESCRIPTION
       This function is atomic and may not be reordered. See __set_bit if you do not require the atomic guarantees.

NOTE
       there are no guarantees that this function will not be reordered on non x86 architectures, so if you are writing portable code, make sure
       not to rely on its reordering guarantees.

       Note that nr may be almost arbitrarily large; this function is not restricted to acting on a single-word quantity.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010								SET_BIT(9)