Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > Ok, so I decided to try to take a look. > > Somebody who actually does networking (and drivers in particular) > should probably check this, but it *looks* like the IPv4 TCP case > (just to pick the ony I looked at) gores through > tcp_sendpage_locked(), which does > > if (!(sk->sk_route_caps & NETIF_F_SG)) > return sock_no_sendpage_locked(sk, page, offset, size, flags); > > which basically says "if you can't handle fragmented socket buffers, > do that 'no_sendpage' case". > > So that will basically end up just falling back to a kernel > 'sendmsg()', which does a copy and then it's stable. > > But for the networks that *can* handle fragmented socket buffers, it > then calls do_tcp_sendpages() instead, which just creates a skb > fragment of the page (with tcp_build_frag()). > > I wonder if that case should just require NETIF_F_HW_CSUM? NETIF_F_SG already depends on checksum offload (either via NETIF_F_HW_CSUM or something else that is equivalent). So are you guys just imagining non-existant problems? Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
