Question: **UPDATED:** Is there a thread-safe, lock-free and available on all Linux distros *increment* function available in C or C++ ?

Answer: 
I think these are GNU extensions, and processor specific, but have a look at [GNU C Atomic Builtins](http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Atomic-Builtins.html).

I think there are also atomic "libraries" available that use inline assembly etc. to provide such features.
The current C and C++ standards don't define such a thing. Your implementation may well have one.