Name
test_and_clear_bit — 
     Clear a bit and return its old value
 
Synopsis
int test_and_clear_bit ( | long nr,  | 
|   | volatile unsigned long * addr); | 
 
Arguments
nr
     Bit to clear
    
addr
     Address to count from
    
Description
   This operation is atomic and cannot be reordered.
   It also implies a memory barrier.