net: dsa: tag_gswip: let DSA core deal with TX reallocation

[ Upstream commit 9b9826ae117f211bcbdc75db844d5fd8b159fc59 ]

Now that we have a central TX reallocation procedure that accounts for
the tagger's needed headroom in a generic way, we can remove the
skb_cow_head call.

This one is interesting, the DSA tag is 8 bytes on RX and 4 bytes on TX.
Because DSA is unaware of asymmetrical tag lengths, the overhead/needed
headroom is declared as 8 bytes and therefore 4 bytes larger than it
needs to be. If this becomes a problem, and the GSWIP driver can't be
converted to a uniform header length, we might need to make DSA aware of
separate RX/TX overhead values.

Cc: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/dsa/tag_gswip.c b/net/dsa/tag_gswip.c
index 408d4af..2f5bd5e 100644 (file)
--- a/net/dsa/tag_gswip.c
+++ b/net/dsa/tag_gswip.c
@@ -60,13 +60,8 @@ static struct sk_buff *gswip_tag_xmit(struct sk_buff *skb,
                                      struct net_device *dev)
 {
        struct dsa_port *dp = dsa_slave_to_port(dev);
-       int err;
        u8 *gswip_tag;
 
-       err = skb_cow_head(skb, GSWIP_TX_HEADER_LEN);
-       if (err)
-               return NULL;
-
        skb_push(skb, GSWIP_TX_HEADER_LEN);
 
        gswip_tag = skb->data;