Name
change_bit — 
     Toggle a bit in memory
 
Synopsis
void change_bit ( | long nr,  | 
|   | volatile unsigned long * addr); | 
 
Arguments
nr
     Bit to change
    
addr
     Address to start counting from
    
Description
   change_bit is atomic and may not be reordered.
   Note that nr may be almost arbitrarily large; this function is not
   restricted to acting on a single-word quantity.