Subject: Re: [PATCH RFC 2/2] veth: propagate bridge GSO to peer

From: Eric Dumazet <[email-masked]>
Date: Thu, 30 Nov 2017 09:26:39 -0800

On Thu, 2017-11-30 at 09:10 -0800, Stephen Hemminger wrote:
> 
> 
> The problem goes back into the core GSO networking code.
> Something like this is needed.
> 
> static inline bool netif_needs_gso(struct sk_buff *skb,
> 				   const struct net_device *dev,
> 				   netdev_features_t features)
> {
> 	return skb_is_gso(skb) &&
> 		(!skb_gso_ok(skb, features) ||
> 		 unlikely(skb_shinfo(skb)->gso_segs > dev-
> >gso_max_segs) ||  << new
> 		 unlikely(skb_shinfo(skb)->gso_size > dev-
> >gso_max_size) ||  << new
> 		 unlikely((skb->ip_summed != CHECKSUM_PARTIAL) &&
> 			  (skb->ip_summed != CHECKSUM_UNNECESSARY)));
> }
> 
> What that will do is split up the monster GSO packets if they ever
> bleed
> across from one device to another through the twisty mazes of packet
> processing paths.

Since very few drivers have these gso_max_segs / gso_max_size, check
could be done in their ndo_features_check()