On Wed, Aug 27, 2025 at 2:06 PM Ilya Maximets <i.maxim...@ovn.org> wrote:
> On 8/26/25 6:26 PM, Ales Musil wrote:
> > Make sure we remove the stale Static MAC Bindings if there is SB
> > datapath re-creation in a single transaction. Otherwise, northd
> > would be stuck in a commit failed loop due to "referential integrity
> > violation" as the static mac binding would still reference the old
> > datapath.
> >
> > At the same time unify the check if dynamic/static mac binding is
> > stale as it was different up until now. Both of them use the same
> > columns as an indication of logical port and datapath.
> >
> > Fixes: b22684d4e37c ("Add a northbound interface to program MAC_Binding
> table")
> > Reported-at: https://issues.redhat.com/browse/FDP-1623
> > Signed-off-by: Ales Musil <amu...@redhat.com>
> > ---
> > v2: Replace the Fixes tags.
> > Remove the redundant check for op->nbrp.
> > Update the commit message with more details.
> > ---
> > northd/northd.c | 28 +++++++++++++++++++---------
> > tests/ovn-northd.at | 8 ++++++++
> > 2 files changed, 27 insertions(+), 9 deletions(-)
> >
> > diff --git a/northd/northd.c b/northd/northd.c
> > index 015f30a35..4b5b6584e 100644
> > --- a/northd/northd.c
> > +++ b/northd/northd.c
> > @@ -2867,6 +2867,19 @@ common:
> > }
> > }
> >
> > +static bool
> > +mac_binding_is_stale(const struct hmap *lr_datapaths,
> > + const struct hmap *lr_ports,
> > + const struct sbrec_datapath_binding *dp,
> > + const char *logical_port)
> > +{
> > + const struct ovn_datapath *od =
> > + ovn_datapath_from_sbrec(NULL, lr_datapaths, dp);
> > +
> > + return !od || ovn_datapath_is_stale(od) ||
> > + !ovn_port_find(lr_ports, logical_port);
> > +}
> > +
> > /* Remove mac_binding entries that refer to logical_ports which are
> > * deleted. */
> > static void
> > @@ -2876,11 +2889,8 @@ cleanup_mac_bindings(
> > {
> > const struct sbrec_mac_binding *b;
> > SBREC_MAC_BINDING_TABLE_FOR_EACH_SAFE (b, sbrec_mac_binding_table) {
> > - const struct ovn_datapath *od =
> > - ovn_datapath_from_sbrec(NULL, lr_datapaths, b->datapath);
> > -
> > - if (!od || ovn_datapath_is_stale(od) ||
> > - !ovn_port_find(lr_ports, b->logical_port)) {
> > + if (mac_binding_is_stale(lr_datapaths, lr_ports, b->datapath,
> > + b->logical_port)) {
> > sbrec_mac_binding_delete(b);
> > }
> > }
> > @@ -18850,7 +18860,7 @@ build_static_mac_binding_table(
> > struct ovsdb_idl_txn *ovnsb_txn,
> > const struct nbrec_static_mac_binding_table *nbrec_static_mb_table,
> > const struct sbrec_static_mac_binding_table *sbrec_static_mb_table,
> > - struct hmap *lr_ports)
> > + const struct hmap *lr_datapaths, const struct hmap *lr_ports)
> > {
> > /* Cleanup SB Static_MAC_Binding entries which do not have
> corresponding
> > * NB Static_MAC_Binding entries, and SB Static_MAC_Binding entries
> for
> > @@ -18866,8 +18876,8 @@ build_static_mac_binding_table(
> > continue;
> > }
> >
> > - struct ovn_port *op = ovn_port_find(lr_ports,
> nb_smb->logical_port);
> > - if (!op || !op->nbrp || !op->od || !op->od->sdp->sb_dp) {
> > + if (mac_binding_is_stale(lr_datapaths, lr_ports,
> sb_smb->datapath,
> > + sb_smb->logical_port)) {
> > sbrec_static_mac_binding_delete(sb_smb);
> > }
>
> FWIW, in addition to obscuring the logic in this function, the change above
> also makes the comment at the top of the loop inaccurate, making the whole
> thing even more confusing. So, at least that should be fixed.
Sure I can update the comment.
>
> The fact that the row will be re-created, but will have the same UUID also
> doesn't sound particularly great.
>
> I'd much prefer a solution like this (not tested):
>
> diff --git a/northd/northd.c b/northd/northd.c
> index 015f30a35..fb494713a 100644
> --- a/northd/northd.c
> +++ b/northd/northd.c
> @@ -18852,28 +18852,16 @@ build_static_mac_binding_table(
> const struct sbrec_static_mac_binding_table *sbrec_static_mb_table,
> struct hmap *lr_ports)
> {
> - /* Cleanup SB Static_MAC_Binding entries which do not have
> corresponding
> - * NB Static_MAC_Binding entries, and SB Static_MAC_Binding entries
> for
> - * which there is not a NB Logical_Router_Port of the same name. */
> - const struct nbrec_static_mac_binding *nb_smb;
> + struct hmapx stale = HMAPX_INITIALIZER(&stale);
> const struct sbrec_static_mac_binding *sb_smb;
> SBREC_STATIC_MAC_BINDING_TABLE_FOR_EACH_SAFE (sb_smb,
> sbrec_static_mb_table) {
> - nb_smb = nbrec_static_mac_binding_table_get_for_uuid(
> - nbrec_static_mb_table, &sb_smb->header_.uuid);
> - if (!nb_smb) {
> - sbrec_static_mac_binding_delete(sb_smb);
> - continue;
> - }
> -
> - struct ovn_port *op = ovn_port_find(lr_ports,
> nb_smb->logical_port);
> - if (!op || !op->nbrp || !op->od || !op->od->sdp->sb_dp) {
> - sbrec_static_mac_binding_delete(sb_smb);
> - }
> + hmapx_add(&stale, CONST_CAST(void *, sb_smb));
> }
>
> /* Create/Update SB Static_MAC_Binding entries with corresponding
> values
> * from NB Static_MAC_Binding entries. */
> + const struct nbrec_static_mac_binding *nb_smb;
> NBREC_STATIC_MAC_BINDING_TABLE_FOR_EACH (
> nb_smb, nbrec_static_mb_table) {
> struct ovn_port *op = ovn_port_find(lr_ports,
> nb_smb->logical_port);
> @@ -18905,10 +18893,22 @@ build_static_mac_binding_table(
>
> sbrec_static_mac_binding_set_override_dynamic_mac(mb,
> nb_smb->override_dynamic_mac);
> }
> + if (od->sdp->sb_dp != mb->datapath) {
> + sbrec_static_mac_binding_set_datapath(
> + mb, od->sdp->sb_dp);
> + }
> + hmapx_find_and_delete(&stale, mb);
> }
> }
> }
> }
> +
> + /* Cleanup SB Static_MAC_Binding entries which are no longer needed.
> */
> + struct hmapx_node *node;
> + HMAPX_FOR_EACH (node, &stale) {
> + sbrec_static_mac_binding_delete(node->data);
> + }
> + hmapx_destroy(&stale);
> }
>
> static void
> ---
>
> This approach is much more robust, since it avoids logic duplication and
> doesn't require a ton of explanation in the comments.
>
Well the logic duplication makes sense here because I don't see any
difference how to define staleness for both dynamic and static mac bindings.
>
>
> Reading this code again, I'm pretty sure there are more bugs here caused
> by the recent UUID unification. AFAICT, if I change IP address in NB,
> it will not be updated in SB. Before the UUID change, lookup was done
> with the port+IP pair and so if we found an entry, it had the right IP,
> but now we're not updating IP and also not checking it in the staleness
> check. May also be a problem if we change the logical port in NB while
> the old one still exists, the staleness check will not catch that.
> So, we need to add more things into the 'update' branch.
>
Yeah there is a bug in the update, I will post a separate patch for that.
>
> Best regards, Ilya Maximets.
>
>
Thanks,
Ales
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