net: dsa: tag_ar9331: Make sure there is headroom for tag

Passing tag size to skb_cow_head will make sure
there is enough headroom for the tag data.
This change does not introduce any overhead in case there
is already available headroom for tag.

Signed-off-by: Per Forlin <perfn@axis.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/dsa/tag_ar9331.c b/net/dsa/tag_ar9331.c
index 466ffa92a4746f0ac0b2860d5af68f3399c35054..55b00694cdba1e75154f4b0f6af0e2f0a14fe9af 100644 (file)
--- a/net/dsa/tag_ar9331.c
+++ b/net/dsa/tag_ar9331.c
@@ -31,7 +31,7 @@ static struct sk_buff *ar9331_tag_xmit(struct sk_buff *skb,
        __le16 *phdr;
        u16 hdr;
 
-       if (skb_cow_head(skb, 0) < 0)
+       if (skb_cow_head(skb, AR9331_HDR_LEN) < 0)
                return NULL;
 
        phdr = skb_push(skb, AR9331_HDR_LEN);