[PATCH 4.19 41/88] net: bcmgenet: hide status block before TX timestamping

Greg Kroah-Hartman
2022-05-10T13:35:13Z

From: Jonathan Lemon <jonathan.lemon@gmail.com>

[ 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>
---
drivers/net/ethernet/broadcom/genet/bcmgenet.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index d4be107ea4cd..96ef2dd46c78 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1549,6 +1549,11 @@ static struct sk_buff *bcmgenet_put_tx_csum(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);
@@ -1657,6 +1662,8 @@ 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 */
--
2.35.1