Why do { // do something ; } while (0); ?

[Shraddha Kamat]

I notice
 
do {
   // do something 1 ; 
   // do something 2 ;
   ...
} while (0); 

being used everywhere in the kernel code
I just can't guess of any use of this other 
than executing couple of C statements together ?

Is there any special purpose of doing this ?? 
Sorry of such a silly question - I am just trying 
to learn kernel hacking basics.

-- Shraddha