itojun@iijlab.net writes:

> 	i don't have any objection in having m_pullup() at the top of
> 	ip_input() for safety, like:
> 		if (m->m_flags & M_EXT)
> 			m = m_pullup(m, sizeof(struct ip));

if we know it is safe, no need to do so.  if we can do something, that
will be asserting that the mbuf isn't shared before modifying it.

enami.