[ovs-dev] [PATCH] ovn-northd: Avoid duplicate logical flows in SB db

[Miguel Angel Ajo Pelayo]

Acked-By: Miguel Angel Ajo <majopela at redhat.com>


On Fri, Jan 5, 2018 at 11:44 AM Daniel Alvarez <dalvarez at redhat.com> wrote:

> When there are two ACLs in a Logical Switch with same direction,
> priority, match and action fields, ovn-northd will generate the
> exact same logical flow for them into SB database. This will make
> ovn-controller log messages (INFO) saying that the duplicate flow
> is going to be dropped.
>
> This patch avoids adding duplicate lflows into SB database so that
> ovn-controller doesn't have to process them.
>
> Signed-off-by: Daniel Alvarez <dalvarez at redhat.com>
> ---
>
> This patch is needed as part of the consistency work we're doing in the
> OpenStack integration [0]. In our effort to ensure consistency across
> objects in Neutron and OVN databases we find some special cases like
> security group rules which match OVN ACLs but not in 1:1 relationship.
> Until now, two identical security group rules beloning each to a
> different security group would generate a single ACL in NB database.
> With this behavior, there's no way to map the ACL in OVN to the
> corresponding Neutron object.
>
> By implementing [0] we're trying to ensure this mapping so we make use
> of the external_ids column of every table for this purpose. It may happen
> that we'll have two identical ACLs but each referencing a different
> Neutron object in their external_ids field. However, this will make
> ovn-northd to generate two duplicate lflows into SB database which will
> make ovn-controller drop them when installing the actual flows. With this
> patch we'll avoid duplicate flows to be inserted in SB database in such
> cases.
>
> [0]
> https://docs.openstack.org/networking-ovn/latest/contributor/design/database_consistency.html
>
>  ovn/northd/ovn-northd.c | 11 +++++++++++
>  tests/ovn-northd.at     | 24 ++++++++++++++++++++++++
>  2 files changed, 35 insertions(+)
>
> diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> index 7e6b1d9..cc64861 100644
> --- a/ovn/northd/ovn-northd.c
> +++ b/ovn/northd/ovn-northd.c
> @@ -428,6 +428,13 @@ struct macam_node {
>      struct eth_addr mac_addr; /* Allocated MAC address. */
>  };
>
> +static struct ovn_lflow *ovn_lflow_find(struct hmap *lflows,
> +                                        struct ovn_datapath *od,
> +                                        enum ovn_stage stage,
> +                                        uint16_t priority,
> +                                        const char *match,
> +                                        const char *actions);
> +
>  static void
>  cleanup_macam(struct hmap *macam)
>  {
> @@ -2298,6 +2305,10 @@ ovn_lflow_add_at(struct hmap *lflow_map, struct
> ovn_datapath *od,
>                   const char *stage_hint, const char *where)
>  {
>      ovs_assert(ovn_stage_to_datapath_type(stage) ==
> ovn_datapath_get_type(od));
> +
> +    if (ovn_lflow_find(lflow_map, od, stage, priority, match, actions)) {
> +        return;
> +    }
>
>      struct ovn_lflow *lflow = xmalloc(sizeof *lflow);
>      ovn_lflow_init(lflow, od, stage, priority,
> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> index 954e259..ba96c81 100644
> --- a/tests/ovn-northd.at
> +++ b/tests/ovn-northd.at
> @@ -152,3 +152,27 @@ ovn-nbctl lsp-set-options S1-R1 router-port=R1-S1
>  AT_CHECK([test x`ovn-nbctl lsp-get-up S1-R1` = xup])
>
>  AT_CLEANUP
> +
> +AT_SETUP([ovn -- check that duplicate acls don't generate duplicate
> lflows])
> +AT_SKIP_IF([test $HAVE_PYTHON = no])
> +ovn_start
> +
> +ovn-nbctl ls-add S1
> +
> +# Insert a duplicate ACL into NB database.
> +ovn-nbctl -- --id=@acl create acl direction=to-lport priority=1000 \
> +    match='"tcp.dst == 22"' action=drop -- add logical_switch S1 acl @acl
> +ovn-nbctl -- --id=@acl create acl direction=to-lport priority=1000 \
> +    match='"tcp.dst == 22"' action=drop -- add logical_switch S1 acl @acl
> +
> +# Check that there are two entries in ACL table in NB database.
> +AT_CHECK([ovn-nbctl find ACL match='"tcp.dst == 22"' | \
> +grep _uuid | wc -l], [0], [2
> +])
> +
> +# Now make sure that only one logical flow is added to SB database.
> +AT_CHECK([ovn-sbctl find Logical_Flow match='"tcp.dst == 22"' | \
> +grep _uuid | wc -l], [0], [1
> +])
> +
> +AT_CLEANUP
> --
> 1.8.3.1
>
> _______________________________________________
> dev mailing list
> dev at openvswitch.org
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>