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 we need a similar check in packet_sendsmg_spkt (even if it > is deprecated, would be better to get it to align with packet_snd?)
That path does not need this check, because it does not support large packets and always allocates the entire packet as linear. > Also tpacket_fill_skb should ensure that copylen is set up like > the code above? 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?
