On Tue, Feb 28, 2017 at 12:43 PM, Willem de Bruijn <willemdebruijn.ker...@gmail.com> wrote: > >> I can see this working if you have a special type of skb that >> indicates that the data might be concurrently written and have all the >> normal skb APIs (including, especially, anything that clones it) make >> a copy first. > > Support for cloned skbs is required for TCP, both at tcp_transmit_skb > and segmentation offload. Patch 4 especially adds reference counting > of shared pages across clones and other sk_buff operations like > pskb_expand_head. This still allows for deep copy (skb_copy_ubufs) > on clones in specific datapaths like the above.
Does this mean that a user program that does a zerocopy send can cause a retransmitted segment to contain different data than the original segment? If so, is that okay?
