Re: why is it not allowed to add a new socket protocol family as an external module?

[Eric Dumazet <eric.dumazet@gmail.com>]

On Wed, 2013-02-20 at 18:44 -0600, Chris Friesen wrote:

> Yes, there are a number of tables sized by NPROTO/AF_MAX/PF_MAX (and the 
> fact that we use all three within the kernel is kind of sad) but there 
> is no technical reason why we couldn't extend those dynamically if 
> desired (with a linked list of additional protocols, perhaps).
> 
> Hence my question--is the restriction for an ideological reason or 
> simply because nobody thought it was worth the effort?
> 

I guess nobody did the preliminary work.

lockdep might be the tricky part.

net/core/sock.c:197:static const char *const af_family_key_strings[AF_MAX+1] = {
net/core/sock.c:211:  "sk_lock-AF_NFC"   , "sk_lock-AF_MAX"
net/core/sock.c:213:static const char *const af_family_slock_key_strings[AF_MAX+1] = {
net/core/sock.c:227:  "slock-AF_NFC"   , "slock-AF_MAX"
net/core/sock.c:229:static const char *const af_family_clock_key_strings[AF_MAX+1] = {
net/core/sock.c:243:  "clock-AF_NFC"   , "clock-AF_MAX"
net/core/sock.c:250:static struct lock_class_key af_callback_keys[AF_MAX];