net: bcmgenet: hide status block before TX timestamping

BugLink: https://bugs.launchpad.net/bugs/1978234
[ Upstream commit acac0541d1d65e81e599ec399d34d184d2424401 ]

The hardware checksum offloading requires use of a transmit
status block inserted before the outgoing frame data, this was
updated in '9a9ba2a4aaaa ("net: bcmgenet: always enable status blocks")'

However, skb_tx_timestamp() assumes that it is passed a raw frame
and PTP parsing chokes on this status block.

Fix this by calling __skb_pull(), which hides the TSB before calling
skb_tx_timestamp(), so an outgoing PTP packet is parsed correctly.

As the data in the skb has already been set up for DMA, and the
dma_unmap_* calls use a separately stored address, there is no
no effective change in the data transmission.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220424165307.591145-1-jonathan.lemon@gmail.com
Fixes: d03825fba459 ("net: bcmgenet: add skb_tx_timestamp call")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index b4f99dd284e53cb3bfb408d408d95c3f39f573ff..8bcc39b1575c23aae21e5f1c43434e10016192ea 100644 (file)
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1991,6 +1991,11 @@ static struct sk_buff *bcmgenet_add_tsb(struct net_device *dev,
        return skb;
 }
 
+static void bcmgenet_hide_tsb(struct sk_buff *skb)
+{
+       __skb_pull(skb, sizeof(struct status_64));
+}
+
 static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct bcmgenet_priv *priv = netdev_priv(dev);
@@ -2097,6 +2102,8 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev)
        }
 
        GENET_CB(skb)->last_cb = tx_cb_ptr;
+
+       bcmgenet_hide_tsb(skb);
        skb_tx_timestamp(skb);
 
        /* Decrement total BD count and advance our write pointer */