NBF_RECVLOCK
ASSERT(nbp->nbp_flags & NBF_RECVLOCK);
if (nbp->nbp_flags & NBF_RECVLOCK) {
nbp->nbp_flags |= NBF_RECVLOCK;
nbp->nbp_flags &= ~NBF_RECVLOCK;
ASSERT(nbp->nbp_flags & NBF_RECVLOCK);