GCC hacks in the Linux kernel

Discover GCC extensions for the C language here.
This article talks about functionality extensions that bring new functionality from GCC and about optimization extensions that are used for generating more efficient code.

One thing that it's easy to remember is using ranges with case statements.
So instead of:

  switch(level){
         case 1:
         case 2:
         case 3: /* do something */
         ......
         default: /* */
        }

you can use:

  switch(level){
         case 1..3: /* do something */
         break;
       }