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From: Hangbin Liu <liuhangbin@gmail.com>
To: netdev@vger.kernel.org
Cc: Guillaume Nault <gnault@redhat.com>,
	Petr Machata <pmachata@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Roopa Prabhu <roopa@cumulusnetworks.com>,
	David Ahern <dsahern@kernel.org>,
	Andreas Karis <akaris@redhat.com>,
	Hangbin Liu <liuhangbin@gmail.com>
Subject: [PATCH net] Revert "vxlan: fix tos value before xmit"
Date: Wed,  5 Aug 2020 10:41:31 +0800	[thread overview]
Message-ID: <20200805024131.2091206-1-liuhangbin@gmail.com> (raw)

This reverts commit 71130f29979c7c7956b040673e6b9d5643003176.

In commit 71130f29979c ("vxlan: fix tos value before xmit") we want to
make sure the tos value are filtered by RT_TOS() based on RFC1349.

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |   PRECEDENCE    |          TOS          | MBZ |
    +-----+-----+-----+-----+-----+-----+-----+-----+

But RFC1349 has been obsoleted by RFC2474. The new DSCP field defined like

       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |          DS FIELD, DSCP           | ECN FIELD |
    +-----+-----+-----+-----+-----+-----+-----+-----+

So with

IPTOS_TOS_MASK          0x1E
RT_TOS(tos)		((tos)&IPTOS_TOS_MASK)

the first 3 bits DSCP info will get lost.

To take all the DSCP info in xmit, we should revert the patch and just push
all tos bits to ip_tunnel_ecn_encap(), which will handling ECN field later.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 drivers/net/vxlan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index a7c3939264b0..35a7d409d8d3 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2722,7 +2722,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 		ndst = &rt->dst;
 		skb_tunnel_check_pmtu(skb, ndst, VXLAN_HEADROOM);
 
-		tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb);
+		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip4_dst_hoplimit(&rt->dst);
 		err = vxlan_build_skb(skb, ndst, sizeof(struct iphdr),
 				      vni, md, flags, udp_sum);
@@ -2762,7 +2762,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 
 		skb_tunnel_check_pmtu(skb, ndst, VXLAN6_HEADROOM);
 
-		tos = ip_tunnel_ecn_encap(RT_TOS(tos), old_iph, skb);
+		tos = ip_tunnel_ecn_encap(tos, old_iph, skb);
 		ttl = ttl ? : ip6_dst_hoplimit(ndst);
 		skb_scrub_packet(skb, xnet);
 		err = vxlan_build_skb(skb, ndst, sizeof(struct ipv6hdr),
-- 
2.25.4


             reply	other threads:[~2020-08-05  2:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-05  2:41 Hangbin Liu [this message]
2020-08-05  8:44 ` [PATCH net] Revert "vxlan: fix tos value before xmit" Guillaume Nault
2020-08-05 10:18   ` Hangbin Liu
2020-08-05 19:11     ` David Miller
2020-08-06  2:52       ` Hangbin Liu
2020-08-12  0:02         ` David Miller
2020-08-12  2:28           ` Hangbin Liu

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