Re: [PATCH net-next v2 3/4] net: add skb_frags_can_coalesce() helper

[Stanislav Fomichev]

On 11/02, Mina Almasry wrote:
> Add skb_has_net_iovs(skb), assuming skb->unreadable and net_iov-backed
> frags are equivalent for now (with a comment noting the two can be
> decoupled in the future if readable net_iovs are introduced).
> 
> Also add skb_mem_provider_compat() and skb_frags_can_coalesce() so all
> multi-skb coalescing, shifting, and GRO paths can share a single check
> across pp_recycle, skb_zcopy(), and fragment memory providers:
> - empty 0-length skbs are compatible without mixing readable payload
> - page vs net_iov is rejected via skb_has_net_iovs() (0 pointer chases)
> - page vs page is allowed via !skb_has_net_iovs() (0 pointer chases)
> - net_iov vs net_iov compares mp_priv (walking frag_list if nr_frags is 0)

Maybe squash this and patch #4? Otherwise hard to follow :-(