netdev - [PATCH net-next 4/6] net: call udp_tunnel_get_rx_info when NETIF_F_TUNNEL

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Date:   Fri, 30 Jun 2017 15:19:48 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     netdev@...r.kernel.org
Cc:     Jiri Benc <jbenc@...hat.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Sabrina Dubroca <sd@...asysnail.net>
Subject: [PATCH net-next 4/6] net: call udp_tunnel_get_rx_info when NETIF_F_TUNNEL_OFFLOAD is toggled

NETIF_F_TUNNEL_OFFLOAD is special, in that we need to do more than just
flip the bit in dev->features. When disabling we must also clear
currently offloaded ports from the device, and when enabling we must
tell the device to offload the ports it can.

Because vxlan stores its sockets in a hashtable and they are inserted
at the head of per-bucket lists, switching the feature off and then on
can result in a different set of ports being offloaded (depending on
the HW's limits).

Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 net/core/dev.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index d97f7b39df23..ba805fba38dd 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -144,6 +144,7 @@
 #include <linux/netfilter_ingress.h>
 #include <linux/crash_dump.h>
 #include <linux/sctp.h>
+#include <net/udp_tunnel.h>
 
 #include "net-sysfs.h"
 
@@ -7302,8 +7303,27 @@ int __netdev_update_features(struct net_device *dev)
 	netdev_for_each_lower_dev(dev, lower, iter)
 		netdev_sync_lower_features(dev, lower, features);
 
-	if (!err)
+	if (!err) {
+		netdev_features_t diff = features ^ dev->features;
+
+		if (diff & NETIF_F_TUNNEL_OFFLOAD) {
+			/* udp_tunnel_{get,drop}_rx_info both need
+			 * NETIF_F_TUNNEL_OFFLOAD enabled on the
+			 * device, or they won't do anything.
+			 * Thus we need to update dev->features
+			 * *before* calling udp_tunnel_get_rx_info,
+			 * but *after* calling udp_tunnel_drop_rx_info.
+			 */
+			if (features & NETIF_F_TUNNEL_OFFLOAD) {
+				dev->features = features;
+				udp_tunnel_get_rx_info(dev);
+			} else {
+				udp_tunnel_drop_rx_info(dev);
+			}
+		}
+
 		dev->features = features;
+	}
 
 	return err < 0 ? 0 : 1;
 }
-- 
2.13.2