why do we use while (0)

["sahlot arvind" <asahlot@xxxxxxxxx>]

Recently I started looking into linux kernel and trying to understand the code.

I am working with linux-2.6.9.

in file include/llinux/list.h - I found something like this.

 

#define INIT_LIST_HEAD(ptr) do { \
        (ptr)->next = (ptr); (ptr)->prev = (ptr); \ 
} while (0)
 

 

My question is why do we use a loop when we actually know that it is not going to execute more than once? Cannot we simply do -

 

#define INIT_LIST_HEAD(ptr)    {(ptr)->next = (ptr); (ptr)->prev = (ptr)}

 

Do we get some kind of optimization by using while (0)?

 

 

Thanks