netback: set transport header before passing it to kernel
Currently, for the packets receives from netback, before doing header check,
kernel just reset the transport header in netif_receive_skb() which pretends non
l4 header. This is suboptimal for precise packet length estimation (introduced
in 1def9238: net_sched: more precise pkt_len computation) which needs correct l4
header for gso packets.
The patch just reuse the header probed by netback for partial checksum packets
and tries to use skb_flow_dissect() for other cases, if both fail, just pretend
no l4 header.
Cc: Eric Dumazet <edumazet@google.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index aa28550..fc8faa7 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -39,6 +39,7 @@
#include <linux/udp.h>
#include <net/tcp.h>
+#include <net/flow_keys.h>
#include <xen/xen.h>
#include <xen/events.h>
@@ -1184,6 +1185,7 @@
if (th >= skb_tail_pointer(skb))
goto out;
+ skb_set_transport_header(skb, 4 * iph->ihl);
skb->csum_start = th - skb->head;
switch (iph->protocol) {
case IPPROTO_TCP:
@@ -1495,6 +1497,7 @@
skb->dev = vif->dev;
skb->protocol = eth_type_trans(skb, skb->dev);
+ skb_reset_network_header(skb);
if (checksum_setup(vif, skb)) {
netdev_dbg(vif->dev,
@@ -1503,6 +1506,15 @@
continue;
}
+ if (!skb_transport_header_was_set(skb)) {
+ struct flow_keys keys;
+
+ if (skb_flow_dissect(skb, &keys))
+ skb_set_transport_header(skb, keys.thoff);
+ else
+ skb_reset_transport_header(skb);
+ }
+
vif->dev->stats.rx_bytes += skb->len;
vif->dev->stats.rx_packets++;
