Name
clear_bit — 
     Clears a bit in memory
 
Synopsis
| void clear_bit ( | long 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_atomic and/or smp_mb__after_atomic
   in order to ensure changes are visible on other processors.