MSG_RCVCOPY
if ((smp->msg_flags & MSG_RCVCOPY) == 0) {
ASSERT((smp->msg_flags & MSG_RCVCOPY) == 0);
smp->msg_flags |= MSG_RCVCOPY;
ASSERT(smp->msg_flags & MSG_RCVCOPY);
smp->msg_flags &= ~MSG_RCVCOPY;
neg_copy_smp.msg_flags = MSG_RCVCOPY;