mbuf: provide m_freemp()

[glebius]

Summary

This function follows both m_nextpkt and m_next linkage freeing all mbufs.
Note that existing m_freem() follows only m_next.

[markj]

sys/kern/kern_mbuf.c

1595

m_freem() lets you pass NULL, but this function does not. Is that deliberate?

[glebius]

sys/kern/kern_mbuf.c

1595

Yes. I believe a good code should not call free(NULL). Of course we are obliged to support free(NULL) in userland and in kernel as well as some other freeing functions, e.g. m_freem(). I will provide a comment on top of m_freemp() that it doesn't support NULL argument.