Re: [PATCH] net:tun: limit printing rate when illegal packet received by tun dev

[Lei Chen]

On Tue, Apr 9, 2024 at 8:52 PM Andrew Lunn <andrew@xxxxxxx> wrote:
>
> On Tue, Apr 09, 2024 at 02:24:05AM -0400, Lei Chen wrote:
> > vhost_worker will call tun call backs to receive packets. If too many
> > illegal packets arrives, tun_do_read will keep dumping packet contents.
> > When console is enabled, it will costs much more cpu time to dump
> > packet and soft lockup will be detected.
> >
> > Rate limit mechanism can be used to limit the dumping rate.
> > @@ -2125,14 +2126,16 @@ static ssize_t tun_put_user(struct tun_struct *tun,
> >                                           tun_is_little_endian(tun), true,
> >                                           vlan_hlen)) {
> >                       struct skb_shared_info *sinfo = skb_shinfo(skb);
> > -                     pr_err("unexpected GSO type: "
> > -                            "0x%x, gso_size %d, hdr_len %d\n",
> > -                            sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
> > -                            tun16_to_cpu(tun, gso.hdr_len));
> > -                     print_hex_dump(KERN_ERR, "tun: ",
> > -                                    DUMP_PREFIX_NONE,
> > -                                    16, 1, skb->head,
> > -                                    min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
> > +
> > +                     if (__ratelimit(&ratelimit)) {
>
> Maybe just use net_ratelimit() rather than add a new ratelimit
> variable?

Thanks for your suggestion, net_ratelimit is a better way to make it.

>
> A separate issue, i wounder if rather than pr_err(),
> netdev_err(tun->dev, ...) should be used to indicate which TUN device
> has been given bad GSO packets?

I got it, I'll remake the patch, thanks.