Fix lock order reversal when calling defrouter_remove() from nd6_na_input(). nd6_na_input() can take lle lock before nd6 lock in certain cases.

[darrick.freebsd_gmail.com]

Summary

Fix lock order reversal in nd6_na_input().

Test Plan

Verified using rawsocket test that LOR no longer occurs.

[markj]

sys/netinet6/nd6_nbr.c

639

These can be of type bool.

removed_defrouter is redundant, you can just initialize dr = NULL and test it.

747

It is rather unfortunate that we have to take a global (well, vnet-global) lock for every NA. :(

885

It can be a bit simpler:

dr = defrouter_lookup_locked(...);
if (dr != NULL) {
    ...
} else if ((ND_IFINFO(nd6_ifp)->flags & ND6_IFF_ACCEPT_RTADV) != 0) {
    ....
}

910

This can be:

if (nd6_locked) {
    ND6_WUNLOCK();
    if (dr != NULL) {
        ...
    }
}

[darrick.freebsd_gmail.com]

• Incorporate CR feedback.

[darrick.freebsd_gmail.com]

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