af_packet: simplify VLAN frame check in packet_snd

For ethernet frames, eth_type_trans() already parses the header, so one
can skip this when checking the frame size.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 11 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2b1470de9e16..0c0f6c9a90e7 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2333,23 +2333,16 @@ static int packet_snd(struct socket *sock,
 
         if (dev->type == ARPHRD_ETHER) {
                 skb->protocol = eth_type_trans(skb, dev);
+                if (skb->protocol == htons(ETH_P_8021Q))
+                        reserve += VLAN_HLEN;
         } else {
                 skb->protocol = proto;
                 skb->dev = dev;
         }
 
         if (!gso_type && (len > dev->mtu + reserve + extra_len)) {
-                /* Earlier code assumed this would be a VLAN pkt,
-                 * double-check this now that we have the actual
-                 * packet in hand.
-                 */
-                struct ethhdr *ehdr;
-                skb_reset_mac_header(skb);
-                ehdr = eth_hdr(skb);
-                if (ehdr->h_proto != htons(ETH_P_8021Q)) {
-                        err = -EMSGSIZE;
-                        goto out_free;
-                }
+                err = -EMSGSIZE;
+                goto out_free;
         }
 
         skb->priority = sk->sk_priority;