Re: [PATCH net-next 2/2] bnxt: Use generic HBH removal helper in tx path

[Alexander Lobakin <alexandr.lobakin@intel.com>]

From: Coco Li <lixiaoyan@google.com>
Date: Tue, 22 Nov 2022 15:27:40 -0800

> Eric Dumazet implemented Big TCP that allowed bigger TSO/GRO packet sizes
> for IPv6 traffic. See patch series:
> 'commit 89527be8d8d6 ("net: add IFLA_TSO_{MAX_SIZE|SEGS} attributes")'
> 
> This reduces the number of packets traversing the networking stack and
> should usually improves performance. However, it also inserts a
> temporary Hop-by-hop IPv6 extension header.
> 
> Using the HBH header removal method in the previous path, the extra header
> be removed in bnxt drivers to allow it to send big TCP packets (bigger
> TSO packets) as well.
> 
> If bnxt folks could help with testing this patch on the driver (as I
> don't have access to one) that would be wonderful. Thank you!
> 
> Tested:
> Compiled locally

Please mark "potential" patches with 'RFC'. Then, if/when you get a
'Tested-by:', you can spin a "true" v1.

> 
> To further test functional correctness, update the GSO/GRO limit on the
> physical NIC:
> 
> ip link set eth0 gso_max_size 181000
> ip link set eth0 gro_max_size 181000
> 
> Note that if there are bonding or ipvan devices on top of the physical
> NIC, their GSO sizes need to be updated as well.
> 
> Then, IPv6/TCP packets with sizes larger than 64k can be observed.
> 
> Signed-off-by: Coco Li <lixiaoyan@google.com>
> ---
>  drivers/net/ethernet/broadcom/bnxt/bnxt.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 0fe164b42c5d..2bfa5e9fb179 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -389,6 +389,9 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  			return NETDEV_TX_BUSY;
>  	}
>  
> +	if (unlikely(ipv6_hopopt_jumbo_remove(skb)))
> +		goto tx_free;
> +
>  	length = skb->len;
>  	len = skb_headlen(skb);
>  	last_frag = skb_shinfo(skb)->nr_frags;
> @@ -13657,6 +13660,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  		dev->features &= ~NETIF_F_LRO;
>  	dev->priv_flags |= IFF_UNICAST_FLT;
>  
> +	netif_set_tso_max_size(dev, GSO_MAX_SIZE);
>  #ifdef CONFIG_BNXT_SRIOV
>  	init_waitqueue_head(&bp->sriov_cfg_wait);
>  #endif
> -- 
> 2.38.1.584.g0f3c55d4c2-goog

Thanks,
Olek