On 01/09/17 12:22, Ido Schimmel wrote:
> Commit 6bc506b4fb06 ("bridge: switchdev: Add forward mark support for
> stacked devices") added the 'offload_fwd_mark' bit to the skb in order
> to allow drivers to indicate to the bridge driver that they already
> forwarded the packet in L2.
>
> In case the bit is set, before transmitting the packet from each port,
> the port's mark is compared with the mark stored in the skb's control
> block. If both marks are equal, we know the packet arrived from a switch
> device that already forwarded the packet and it's not re-transmitted.
>
> However, if the packet is transmitted from the bridge device itself
> (e.g., br0), we should clear the 'offload_fwd_mark' bit as the mark
> stored in the skb's control block isn't valid.
>
> This scenario can happen in rare cases where a packet was trapped during
> L3 forwarding and forwarded by the kernel to a bridge device.
>
> Fixes: 6bc506b4fb06 ("bridge: switchdev: Add forward mark support for stacked devices")
> Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
> Reported-by: Yotam Gigi <yotamg@xxxxxxxxxxxx>
> Tested-by: Yotam Gigi <yotamg@xxxxxxxxxxxx>
> Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
> ---
> net/bridge/br_device.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
> index 861ae2a165f4..5a7be3bddfa9 100644
> --- a/net/bridge/br_device.c
> +++ b/net/bridge/br_device.c
> @@ -53,6 +53,9 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
> brstats->tx_bytes += skb->len;
> u64_stats_update_end(&brstats->syncp);
>
> +#ifdef CONFIG_NET_SWITCHDEV
> + skb->offload_fwd_mark = 0;
> +#endif
> BR_INPUT_SKB_CB(skb)->brdev = dev;
>
> skb_reset_mac_header(skb);
>
Good catch, just one minor nit since there is already an ifdef
switchdev/else in br_private.h, why not make this a helper and avoid the
ifdef/endif in here ? Currently there is no ifdef switchdev anywhere else.
Thanks,
Nik
