From 200129b8df5e0d9beb3f24b4fb1efb587526c0ec Mon Sep 17 00:00:00 2001
From: Claudio Jeker <claudio@cvs.openbsd.org>
Date: Thu, 16 Mar 2006 09:30:55 +0000
Subject: Switch tun(4) from encapsualting packets into a long mbuf chain over
 to use mbuf clusters if the packet is big enough. This should speed up tun(4)
 and may help in other cases where long mbuf chains hurt. Additionally switch
 the default tun(4) MTU to a more sane 1500 bytes. TUNMTU is kept because it
 is used in userland. Input and OK from brad@ and djm@

---
 sys/net/if_tun.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/sys/net/if_tun.c b/sys/net/if_tun.c
index aacce07d36c..e2bddf1183a 100644
--- a/sys/net/if_tun.c
+++ b/sys/net/if_tun.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_tun.c,v 1.76 2006/03/05 02:35:38 brad Exp $	*/
+/*	$OpenBSD: if_tun.c,v 1.77 2006/03/16 09:30:54 claudio Exp $	*/
 /*	$NetBSD: if_tun.c,v 1.24 1996/05/07 02:40:48 thorpej Exp $	*/
 
 /*
@@ -200,7 +200,7 @@ tun_create(struct if_clone *ifc, int unit, int flags)
 	IFQ_SET_READY(&ifp->if_snd);
 	if ((flags & TUN_LAYER2) == 0) {
 		tp->tun_flags &= ~TUN_LAYER2;
-		ifp->if_mtu = TUNMTU;
+		ifp->if_mtu = ETHERMTU;
 		ifp->if_flags = IFF_POINTOPOINT;
 		ifp->if_type = IFT_TUNNEL;
 		ifp->if_hdrlen = sizeof(u_int32_t);
@@ -828,6 +828,14 @@ tunwrite(dev_t dev, struct uio *uio, int ioflag)
 	if (m == NULL)
 		return (ENOBUFS);
 	mlen = MHLEN;
+	if (uio->uio_resid >= MINCLSIZE) {
+		MCLGET(m, M_DONTWAIT);
+		if (!(m->m_flags & M_EXT)) {
+			m_freem(m);
+			return (ENOBUFS);
+		}
+		mlen = MCLBYTES;
+	}
 
 	top = NULL;
 	mp = &top;
@@ -851,6 +859,14 @@ tunwrite(dev_t dev, struct uio *uio, int ioflag)
 				break;
 			}
 			mlen = MLEN;
+			if (uio->uio_resid >= MINCLSIZE) {
+				MCLGET(m, M_DONTWAIT);
+				if (!(m->m_flags & M_EXT)) {
+					error = ENOBUFS;
+					break;
+				}
+				mlen = MCLBYTES;
+			}
 		}
 	}
 	if (error) {
-- 
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