Use M_ZERO with malloc rather than calling bzero() ourselves.
Change if () panic() checks to KASSERT()s as they are only
catching invariants in code flow but not dependent on network
input/output.
Move initial assigments indirecting pointers after the lock
has been aquired.
Passing layer boundries, reset M_PROTOFLAGS.
Remove a NULL assignment before free.
Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems
Reviewed by: gnn (as part of the whole)
MFC After: 3 days