o eliminate widespread on-stack mbuf use for bpf by introducing

  a new bpf_mtap2 routine that does the right thing for an mbuf
  and a variable-length chunk of data that should be prepended.
o while we're sweeping the drivers, use u_int32_t uniformly when
  when prepending the address family (several places were assuming
  sizeof(int) was 4)
o return M_ASSERTVALID to BPF_MTAP* now that all stack-allocated
  mbufs have been eliminated; this may better be moved to the bpf
  routines

Reviewed by:	arch@ and several others

1 files changed, 1 insertions, 12 deletions

diff --git a/sys/dev/ppbus/if_plip.c b/sys/dev/ppbus/if_plip.c
index ab02841..32221c7 100644
--- a/sys/dev/ppbus/if_plip.c
+++ b/sys/dev/ppbus/if_plip.c
@@ -445,19 +445,8 @@ clpinbyte (int spin, device_t ppbus)
 static void
 lptap(struct ifnet *ifp, struct mbuf *m)
 {
-	/*
-	 * Send a packet through bpf. We need to prepend the address family
-	 * as a four byte field. Cons up a dummy header to pacify bpf. This
-	 * is safe because bpf will only read from the mbuf (i.e., it won't
-	 * try to free it or keep a pointer to it).
-	 */
 	u_int32_t af = AF_INET;
-	struct mbuf m0;
-	
-	m0.m_next = m;
-	m0.m_len = sizeof(u_int32_t);
-	m0.m_data = (char *)⁡
-	BPF_MTAP(ifp, &m0);
+	BPF_MTAP2(ifp, &af, sizeof(af), m);
 }
 
 static void