[ovs-dev] [PATCH] dpif-netilnk: convert packet_type netlink attribute

[Zoltán Balogh]

Thank you for reviewing!
I'm going to fix it.
/Zoltan

> -----Original Message-----
> From: Eric Garver [mailto:e at erig.me]
> Sent: Monday, July 03, 2017 8:52 PM
> To: Zoltán Balogh <zoltan.balogh at ericsson.com>
> Cc: 'dev at openvswitch.org' <dev at openvswitch.org>
> Subject: Re: [ovs-dev] [PATCH] dpif-netilnk: convert packet_type netlink attribute
> 
> On Mon, Jul 03, 2017 at 02:27:18PM +0000, Zoltán Balogh wrote:
> > By introducing packet type-aware pipeline, match on ethertype was
> > removed when packet type is not Ethernet. As pointed out by Eric Garver,
> > this could have a side effect on the kernel datapath:
> > https://patchwork.ozlabs.org/patch/782991/
> >
> > This patch does approach the problem from a different perspective.
> > Instead of re-introducing the unconditional match on Ethernet type in all
> > megaflow entries, as suggested by Eric, mapping of packet_type != PT_ETH to
> > dl_type could be handled in the put_exclude_packet_type() in dpif-netlink.c.
> >
> > Put_exclude_packet_type() filters the packet_type netlink attribute out,
> > before all attributes are sent from userspace to kernel. This commit modifies
> > the put_exclude_packet_type() function to do a proper conversation and add the
> > missing OVS_KEY_ATTR_ETHERTYPE attribute if it's needed.
> >
> > Signed-off-by: Zoltán Balogh <zoltan.balogh at ericsson.com>
> > Reported-by: Eric Garver <e at erig.me>
> > ---
> >  lib/dpif-netlink.c | 34 ++++++++++++++++++++++++++++------
> >  1 file changed, 28 insertions(+), 6 deletions(-)
> >
> > diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
> > index 562f6134c..d8051a09e 100644
> > --- a/lib/dpif-netlink.c
> > +++ b/lib/dpif-netlink.c
> > @@ -3434,11 +3434,11 @@ dpif_netlink_flow_from_ofpbuf(struct dpif_netlink_flow *flow,
> >
> >
> >  /*
> > - * If PACKET_TYPE attribute is present in 'data', it filters PACKET_TYPE out,
> > - * then puts 'data' to 'buf'.
> > + * If PACKET_TYPE attribute is present in 'data', converts it to ETHERNET and
> > + * ETHERTYPE attributes, then puts 'data' to 'buf'.
> >   */
> >  static void
> > -put_exclude_packet_type(struct ofpbuf *buf, uint16_t type,
> > +put_convert_packet_type(struct ofpbuf *buf, uint16_t type,
> >                          const struct nlattr *data, uint16_t data_len)
> >  {
> >      const struct nlattr *packet_type;
> > @@ -3446,8 +3446,9 @@ put_exclude_packet_type(struct ofpbuf *buf, uint16_t type,
> >      packet_type = nl_attr_find__(data, data_len, OVS_KEY_ATTR_PACKET_TYPE);
> >
> >      if (packet_type) {
> > -        /* exclude PACKET_TYPE Netlink attribute. */
> > +        /* Convert PACKET_TYPE Netlink attribute. */
> >          ovs_assert(NLA_ALIGN(packet_type->nla_len) == NL_A_U32_SIZE);
> > +        ovs_be32 value = nl_attr_get_be32(packet_type);
> >          size_t packet_type_len = NL_A_U32_SIZE;
> >          size_t first_chunk_size = (uint8_t *)packet_type - (uint8_t *)data;
> >          size_t second_chunk_size = data_len - first_chunk_size
> > @@ -3455,10 +3456,31 @@ put_exclude_packet_type(struct ofpbuf *buf, uint16_t type,
> >          uint8_t *first_attr = NULL;
> >          struct nlattr *next_attr = nl_attr_next(packet_type);
> >
> > +        bool ethernet_present = nl_attr_find__(data, data_len,
> > +                                               OVS_KEY_ATTR_ETHERNET);
> > +
> >          first_attr = nl_msg_put_unspec_uninit(buf, type,
> >                                                data_len - packet_type_len);
> >          memcpy(first_attr, data, first_chunk_size);
> >          memcpy(first_attr + first_chunk_size, next_attr, second_chunk_size);
> > +
> > +        /* Put OVS_KEY_ATTR_ETHERTYPE if needed. */
> > +        if (ntohl(value) == PT_ETH) {
> 
> I don't think this works for the mask case. I think value will be
> OVS_BE32_MAX.
> 
> > +            ovs_assert(ethernet_present);
> > +        } else {
> > +            const struct nlattr *eth_type;
> > +            ovs_be16 ns_type = pt_ns_type_be(value);
> > +
> > +            ovs_assert(ethernet_present == false);
> > +
> > +            eth_type = nl_attr_find__(data, data_len, OVS_KEY_ATTR_ETHERTYPE);
> > +            if (eth_type) {
> > +                ovs_assert(nl_attr_get_be16(eth_type) == ns_type);
> > +            } else {
> > +                nl_msg_put_be16(buf, OVS_KEY_ATTR_ETHERTYPE, ns_type);
> 
> This will have to put OVS_BE16_MAX for mask case.
> 
> > +            }
> > +        }
> > +
> >      } else {
> >          nl_msg_put_unspec(buf, type, data, data_len);
> >      }
> > @@ -3489,11 +3511,11 @@ dpif_netlink_flow_to_ofpbuf(const struct dpif_netlink_flow *flow,
> >      }
> >      if (!flow->ufid_terse || !flow->ufid_present) {
> >          if (flow->key_len) {
> > -            put_exclude_packet_type(buf, OVS_FLOW_ATTR_KEY, flow->key,
> > +            put_convert_packet_type(buf, OVS_FLOW_ATTR_KEY, flow->key,
> >                                             flow->key_len);
> >          }
> >          if (flow->mask_len) {
> > -            put_exclude_packet_type(buf, OVS_FLOW_ATTR_MASK, flow->mask,
> > +            put_convert_packet_type(buf, OVS_FLOW_ATTR_MASK, flow->mask,
> >                                             flow->mask_len);
> >          }
> >          if (flow->actions || flow->actions_len) {
> > --
> > 2.11.0
> >
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