Hello,

We are working on new protocols and we think that is useful to have some 
address protocol families index assigned for local use. So we will not have 
conflict every time a new protocol is included within the Linux kernel.
Doubt: index 27 and 28 are not assigned to any address family, can be 
explicitly assigned for local use?

We also thought to increase AF_MAX to 64 to avoid to modify it every time.
Doubt: array like af_family_key_strings (net/core/sock.c) will have some NULL 
pointer. I see that a string is specified also for index 27 and 28 even if 
there is not a protocol assigned for these. Is a NULL string a problem for 
these vectors? Typically is used in this way:

    af_family_clock_key_strings[newsk->sk_family]

So, if I set sk_family with an unassigned index I will have a NULL pointer and 
a DEBUG_LOCK_WARN_ON() from lockdep_init_map() (kernel/lockdep.c)


I attached to this email the patch that do these stuff.

-- 
Federico Vaga