netdev - Re: [RFC net-next v3 2/2] bnxt: Use generic HBH removal helper in tx path

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Message-ID: <CADjXwjgJtXQx14h4_aSYiEHgZjGsYVGEs+LKm13BkweZFAtUUQ@mail.gmail.com>
Date:   Thu, 1 Dec 2022 18:03:06 -0800
From:   Coco Li <lixiaoyan@...gle.com>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC net-next v3 2/2] bnxt: Use generic HBH removal helper in tx path

On Tue, Nov 29, 2022 at 12:42 PM Michael Chan <michael.chan@...adcom.com> wrote:
>
> On Tue, Nov 29, 2022 at 12:07 PM Coco Li <lixiaoyan@...gle.com> wrote:
> > diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> > index 0fe164b42c5d..f144a5ef2e04 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;
> > @@ -11342,9 +11345,15 @@ static bool bnxt_exthdr_check(struct bnxt *bp, struct sk_buff *skb, int nw_off,
> >
> >                 if (hdrlen > 64)
> >                         return false;
> > +
> > +               /* The ext header may be a hop-by-hop header inserted for
> > +                * big TCP purposes. This will be removed before sending
> > +                * from NIC, so do not count it.
> > +                */
> > +               if (!(*nexthdr == NEXTHDR_HOP && ipv6_has_hopopt_jumbo(skb)))
>
> To be more efficient, why not just check the header's tlv_type here
> instead of calling ipv6_has_hopopt_jumbo()?
>

It may be possible that the next header is Hop_by_hop but the packet
is not tcp, meaning that it would not be removed and we'd still want
to count this header towards the limit.
ipv6_has_hopopt_jumbo checks for the big tcp case (gso, skb len
reaches a certain size) particularly.

> > +                       hdr_count++;
> >                 nexthdr = &hp->nexthdr;
> >                 start += hdrlen;
> > -               hdr_count++;
> >         }
> >         if (nextp) {
> >                 /* Caller will check inner protocol */
> > @@ -13657,6 +13666,8 @@ 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
> >