m_clget
m_clget(m, M_DONTWAIT, len + headspace);
m = m_clget(NULL, M_DONTWAIT, MCLBYTES);
m_clget(m, M_WAITOK, uio->uio_resid);
m_clget(m, M_DONTWAIT, alen);
if ((mc = m_clget(NULL, M_NOWAIT, out_len + max_hdr)) == NULL)
#define MCLGET(m, how) (void) m_clget((m), (how), MCLBYTES)
#define MCLGETL(m, how, l) m_clget((m), (how), (l))
struct mbuf *m_clget(struct mbuf *, int, u_int);