[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH net-next v3 2/5] xen-netback: add support for IPv6 checksum offload from guest
> -----Original Message----- > From: Wei Liu [mailto:wei.liu2@xxxxxxxxxx] > Sent: 11 October 2013 11:10 > To: Paul Durrant > Cc: xen-devel@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Wei Liu; David Vrabel; > Ian Campbell > Subject: Re: [PATCH net-next v3 2/5] xen-netback: add support for IPv6 > checksum offload from guest > > On Thu, Oct 10, 2013 at 04:25:30PM +0100, Paul Durrant wrote: > [...] > > -#define PKT_PROT_LEN (ETH_HLEN + \ > > - VLAN_HLEN + \ > > - sizeof(struct iphdr) + MAX_IPOPTLEN + \ > > - sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE) > > +#define PKT_PROT_LEN 128 > > I'm not against changing this, but could you please add comment on why > 128 is chosen. > Hmm. I did mod the comment, but that change seems to have got lost somewhere. > > > [...] > > + while ((off <= sizeof(struct ipv6hdr) + ntohs(ipv6h->payload_len)) > && > > + !done) { > > + switch (nexthdr) { > > + case IPPROTO_FRAGMENT: { > > + struct frag_hdr *hp = (void *)(skb->data + off); > > + > > + header_size = skb->network_header + > > + off + > > + sizeof(struct frag_hdr); > > + maybe_pull_tail(skb, header_size); > > + > > + nexthdr = hp->nexthdr; > > + off += 8; > > Can you use sizeof(frag_hdr) instead of 8? > > > + break; > > + } > > + case IPPROTO_DSTOPTS: > > + case IPPROTO_HOPOPTS: > > + case IPPROTO_ROUTING: { > > + struct ipv6_opt_hdr *hp = (void *)(skb->data + off); > > + > > + header_size = skb->network_header + > > + off + > > + sizeof(struct ipv6_opt_hdr); > > + maybe_pull_tail(skb, header_size); > > + > > + nexthdr = hp->nexthdr; > > + off += ipv6_optlen(hp); > > + break; > > + } > > + case IPPROTO_AH: { > > + struct ip_auth_hdr *hp = (void *)(skb->data + off); > > + > > + header_size = skb->network_header + > > + off + > > + sizeof(struct ip_auth_hdr); > > + maybe_pull_tail(skb, header_size); > > + > > + nexthdr = hp->nexthdr; > > + off += (hp->hdrlen+2)<<2; > > + break; > > + } > > + case IPPROTO_TCP: > > + case IPPROTO_UDP: > > + found = true; > > + /* Fall through */ > > + default: > > + done = true; > > + break; > > The above 'switch' doesn't seem to cover all IPPROTO_*. Will it cause > the loop to exit too early? In other words, does any IPPROTO_* not > listed above marks the end of parsing? > AFAIK, hitting anything not in that switch would mean we don't have a TCP or UDP packet. I think the original code structure made that clearer so I'm going to go back to that. > [...] > > unsigned long now = jiffies; > > @@ -1428,12 +1598,7 @@ static int xenvif_tx_submit(struct xenvif *vif, int > budget) > > > > xenvif_fill_frags(vif, skb); > > > > - /* > > - * If the initial fragment was < PKT_PROT_LEN then > > - * pull through some bytes from the other fragments to > > - * increase the linear region to PKT_PROT_LEN bytes. > > - */ > > - if (skb_headlen(skb) < PKT_PROT_LEN && > skb_is_nonlinear(skb)) { > > + if (skb_is_nonlinear(skb) && skb_headlen(skb) < > PKT_PROT_LEN) { > > This change is not necessary: the comment is useful, and swapping two > operands of && doesn't have any effect. Sorry, that was too much cutting and pasting around. I'll just ditch that hunk. Paul > > Wei. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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