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tuntap: set transport header before passing it to kernel 

Currently, for the packets receives from tuntap, before doing header check,
kernel just reset the transport header in netif_receive_skb() which pretends no
l4 header. This is suboptimal for precise packet length estimation (introduced
in 1def9238) which needs correct l4 header for gso packets.

So this patch set the transport header to csum_start for partial checksum
packets, otherwise it first try skb_flow_dissect(), if it fails, just reset the
transport header.

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2013-03-25 20:19:56 +00:00 committed by David S. Miller
parent 9b4d669bc0
commit 38502af77e
1 changed files with 10 additions and 0 deletions
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10
drivers/net/tun.c
View File

@ -70,6 +70,7 @@
#include <net/sock.h>
#include <asm/uaccess.h>
#include <net/flow_keys.h>
/* Uncomment to enable debugging */
/* #define TUN_DEBUG 1 */
@ -1049,6 +1050,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
bool zerocopy = false;
int err;
u32 rxhash;
struct flow_keys keys;
if (!(tun->flags & TUN_NO_PI)) {
if ((len -= sizeof(pi)) > total_len)
@ -1203,6 +1205,14 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
}
skb_reset_network_header(skb);
if (skb->ip_summed == CHECKSUM_PARTIAL)
skb_set_transport_header(skb, skb_checksum_start_offset(skb));
else if (skb_flow_dissect(skb, &keys))
skb_set_transport_header(skb, keys.thoff);
else
skb_reset_transport_header(skb);
rxhash = skb_get_rxhash(skb);
netif_rx_ni(skb);