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, 3 insertions, 19 deletions

diff --git a/sys/dev/iicbus/if_ic.c b/sys/dev/iicbus/if_ic.c
index a98720f..e712b9b 100644
--- a/sys/dev/iicbus/if_ic.c
+++ b/sys/dev/iicbus/if_ic.c
@@ -66,7 +66,7 @@ __FBSDID("$FreeBSD$");
 
 #define PCF_MASTER_ADDRESS 0xaa
 
-#define ICHDRLEN	sizeof(u_int)
+#define ICHDRLEN	sizeof(u_int32_t)
 #define ICMTU		1500		/* default mtu */
 
 struct ic_softc {
@@ -369,7 +369,7 @@ icoutput(struct ifnet *ifp, struct mbuf *m,
 	int s, len, sent;
 	struct mbuf *mm;
 	u_char *cp;
-	u_int hdr = dst->sa_family;
+	u_int32_t hdr = dst->sa_family;
 
 	ifp->if_flags |= IFF_RUNNING;
 
@@ -400,23 +400,7 @@ icoutput(struct ifnet *ifp, struct mbuf *m,
 
 	} while ((mm = mm->m_next));
 
-	if (ifp->if_bpf) {
-		struct mbuf m0, *n = m;
-
-		/*
-		 * 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 a to it).
-		 */
-		m0.m_next = m;
-		m0.m_len = sizeof(u_int);
-		m0.m_data = (char *)&hdr;
-		n = &m0;
-
-		BPF_MTAP(ifp, n);
-	}
+	BPF_MTAP2(ifp, &hdr, sizeof(hdr), m);
 
 	sc->ic_sending = 1;