On (02/08/17 08:37), Willem de Bruijn wrote: > Date: Wed, 8 Feb 2017 08:37:19 -0800 > From: Willem de Bruijn <willemdebruijn.ker...@gmail.com> > To: Sowmini Varadhan <sowmini.varad...@oracle.com> > Cc: Network Development <netdev@vger.kernel.org>, David Miller > <da...@davemloft.net>, Eric Dumazet <eric.duma...@gmail.com>, Dmitry > Vyukov <dvyu...@google.com>, Willem de Bruijn <will...@google.com> > Subject: Re: [PATCH net 2/2] packet: round up linear to header len > > On Wed, Feb 8, 2017 at 7:34 AM, Sowmini Varadhan > <sowmini.varad...@oracle.com> wrote: > > On (02/07/17 15:57), Willem de Bruijn wrote: > >> @@ -2816,8 +2816,9 @@ static int packet_snd(struct socket *sock, struct > >> msghdr *msg, size_t len) > >> err = -ENOBUFS; > >> hlen = LL_RESERVED_SPACE(dev); > >> tlen = dev->needed_tailroom; > >> - skb = packet_alloc_skb(sk, hlen + tlen, hlen, len, > >> - __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len), > >> + linear = __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len); > >> + linear = max(linear, min_t(int, len, dev->hard_header_len)); > >> + skb = packet_alloc_skb(sk, hlen + tlen, hlen, len, linear, > >> msg->msg_flags & MSG_DONTWAIT, &err); > > : > Do you mean the difference that it unconditionally pulls > hard_header_len, optionally with zero padding, whereas this new > path can check against new min_header_len and thus allows > packets shorter than hard_header_len?
yes, maybe it doesnt matter, becaues hard_header_len >= min_header_len at all times --Sowmini
