__TEST_AND_SET_BIT

Section: Basic C Library Functions (9)
Updated: February 2011
Index Return to Main Contents
 

NAME

__test_and_set_bit - Set a bit and return its old value  

SYNOPSIS

int __test_and_set_bit(int nr, volatile unsigned long * addr);
 

ARGUMENTS

nr

Bit to set

addr

Address to count from
 

DESCRIPTION

This operation is non-atomic and can be reordered. If two examples of this operation race, one can appear to succeed but actually fail. You must protect multiple accesses with a lock.  

COPYRIGHT