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bgpd: rework the force_update logic in adjout
On Wed, Jul 15, 2026 at 12:02:39PM +0200, Claudio Jeker wrote:
> On initial connect the system needs to sync the adj-rib-out of a peer with
> the Loc-RIB. This happens via peer_dump() and in this case the system
> needs to push out all updates (but can drop any withdraw).
>
> The other user of peer_dump() is during config reloads where the RIB of a
> peer is altered. In that case the adj-rib-out is first flushed
> (withdrawing all paths) and then refilled via peer_dump(). Again in that
> case all updates should be pushed out and there should be no withdraw at
> all since the table was just flushed.
>
> To do this a force_update flag was introduced but actually it is better to
> use the mode and introduce EVAL_SYNC for this case.
> If mode == EVAL_SYNC adjout_prefix_update needs to force the update and
> adjout_prefix_withdraw can drop the withdraw.
I like this.
> While there also remove the NOTYET bits in peer_generate_update() and
> replace them with a simple hack inside up_generate_addpath_all()
> to just call up_generate_addpath().
>
> This is another stepping stone to bring back the add-path send all
> optimisation.
ok tb
> --
> :wq Claudio
>
> Index: rde.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde.c,v
> diff -u -p -r1.708 rde.c
> --- rde.c 1 Jul 2026 09:53:47 -0000 1.708
> +++ rde.c 15 Jul 2026 09:43:03 -0000
> @@ -3671,7 +3671,7 @@ rde_up_flush_upcall(struct pt_entry *pte
> {
> struct rde_peer *peer = ptr;
>
> - adjout_prefix_withdraw(peer, pte, p);
> + adjout_prefix_withdraw(peer, pte, p, 0);
> }
>
> int
> Index: rde.h
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde.h,v
> diff -u -p -r1.357 rde.h
> --- rde.h 13 Jul 2026 12:27:34 -0000 1.357
> +++ rde.h 15 Jul 2026 09:32:29 -0000
> @@ -359,6 +359,7 @@ struct filterstate {
>
> enum eval_mode {
> EVAL_NONE,
> + EVAL_SYNC,
> EVAL_REEVAL,
> EVAL_DEFAULT,
> EVAL_ALL,
> @@ -777,7 +778,7 @@ struct adjout_prefix *adjout_prefix_next
> void adjout_prefix_update(struct adjout_prefix *, struct rde_peer *,
> struct filterstate *, struct pt_entry *, uint32_t, int);
> void adjout_prefix_withdraw(struct rde_peer *, struct pt_entry *,
> - struct adjout_prefix *);
> + struct adjout_prefix *, int);
> void adjout_prefix_reaper(struct rde_peer *);
> void adjout_prefix_dump_cleanup(struct rib_context *);
> void adjout_prefix_dump_r(struct rib_context *);
> @@ -808,9 +809,12 @@ void pend_prefix_stats(struct ch_stats
> void adjout_attr_stats(struct ch_stats *);
>
> /* rde_update.c */
> -void up_generate_updates(struct rde_peer *, struct rib_entry *, int);
> -void up_generate_addpath(struct rde_peer *, struct rib_entry *, int);
> -void up_generate_addpath_all(struct rde_peer *, struct rib_entry *, int);
> +void up_generate_updates(struct rde_peer *, struct rib_entry *,
> + enum eval_mode);
> +void up_generate_addpath(struct rde_peer *, struct rib_entry *,
> + enum eval_mode);
> +void up_generate_addpath_all(struct rde_peer *, struct rib_entry *,
> + enum eval_mode);
> void up_generate_default(struct rde_peer *, uint8_t);
> int up_is_eor(struct rde_peer *, uint8_t);
> void up_dump_withdraws(struct imsgbuf *, struct rde_peer *, uint8_t);
> Index: rde_adjout.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde_adjout.c,v
> diff -u -p -r1.21 rde_adjout.c
> --- rde_adjout.c 13 Jul 2026 12:27:34 -0000 1.21
> +++ rde_adjout.c 15 Jul 2026 09:32:29 -0000
> @@ -516,11 +516,12 @@ adjout_prefix_next(struct pt_entry *pte,
>
> /*
> * Put a prefix from the Adj-RIB-Out onto the update queue.
> + * If force_send is set, ensure an UPDATE is sent in any case to the peer.
> */
> void
> adjout_prefix_update(struct adjout_prefix *p, struct rde_peer *peer,
> struct filterstate *state, struct pt_entry *pte, uint32_t path_id_tx,
> - int force_update)
> + int force_send)
> {
> struct adjout_attr *attrs;
>
> @@ -542,7 +543,7 @@ adjout_prefix_update(struct adjout_prefi
> attrs->communities) &&
> path_equal(&state->aspath, attrs->aspath)) {
> /* nothing changed */
> - if (force_update && peer_is_up(peer))
> + if (force_send && peer_is_up(peer))
> pend_prefix_add(peer, attrs, pte, path_id_tx);
> return;
> }
> @@ -563,15 +564,16 @@ adjout_prefix_update(struct adjout_prefi
> /*
> * Withdraw a prefix from the Adj-RIB-Out, this unlinks the aspath but leaves
> * the prefix in the RIB linked to the peer withdraw list.
> + * If skip_send is set there is no need to send a withdraw to the peer.
> */
> void
> adjout_prefix_withdraw(struct rde_peer *peer, struct pt_entry *pte,
> - struct adjout_prefix *p)
> + struct adjout_prefix *p, int skip_send)
> {
> if (bitmap_test(&p->peermap, peer->adjout_bid) == 0)
> fatalx("%s: king bula is unhappy", __func__);
>
> - if (peer_is_up(peer))
> + if (peer_is_up(peer) && !skip_send)
> pend_prefix_add(peer, NULL, pte, p->path_id_tx);
>
> adjout_prefix_unlink(p, pte, peer);
> Index: rde_peer.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde_peer.c,v
> diff -u -p -r1.79 rde_peer.c
> --- rde_peer.c 13 Jul 2026 12:27:34 -0000 1.79
> +++ rde_peer.c 15 Jul 2026 09:36:22 -0000
> @@ -244,7 +244,7 @@ RB_GENERATE(peer_tree, rde_peer, entry,
>
> static void
> peer_generate_update(struct rde_peer *peer, struct rib_entry *re,
> - enum eval_mode mode, int force_update)
> + enum eval_mode mode)
> {
> uint8_t aid;
>
> @@ -269,26 +269,17 @@ peer_generate_update(struct rde_peer *pe
>
> /* handle peers with add-path */
> if (peer_has_add_path(peer, aid, CAPA_AP_SEND)) {
> -#if NOTYET
> - /* XXX skip addpath all optimisation for now until the queue
> - * is extended to allow this mode to work again.
> - * This mode is not very common and so taking the slow path
> - * here like for all other addpath send modes is not that
> - * big of an issue right now.
> - */
> - if (peer->eval.mode == ADDPATH_EVAL_ALL) {
> - up_generate_addpath_all(peer, re, force_update);
> - return;
> - }
> -#endif
> - up_generate_addpath(peer, re, force_update);
> + if (peer->eval.mode == ADDPATH_EVAL_ALL)
> + up_generate_addpath_all(peer, re, mode);
> + else
> + up_generate_addpath(peer, re, mode);
> return;
> }
>
> /* skip regular peers if the best path didn't change */
> if (mode == EVAL_ALL && (peer->flags & PEERFLAG_EVALUATE_ALL) == 0)
> return;
> - up_generate_updates(peer, re, force_update);
> + up_generate_updates(peer, re, mode);
> }
>
> /*
> @@ -298,8 +289,8 @@ peer_generate_update(struct rde_peer *pe
> * EVAL_ALL is sent for any other update (needed for peers with
> * addpath or evaluate all set).
> * EVAL_REEVAL is used by config reloads (a full RIB refresh is needed)
> - * and for single peer RIB dumps but those call peer_generate_update()
> - * directly.
> + * EVAL_SYNC is used for single peer RIB dumps but those call
> + * peer_generate_update() directly.
> * peer, newpath and old_pathid_tx are ignored if mode is EVAL_REEVAL.
> * In the other cases either newpath or old_pathid_tx are valid but not
> * both at the same time.
> @@ -317,13 +308,14 @@ rde_enqueue_updates(struct rib_entry *re
> RB_FOREACH(p, peer_tree, &peertable) {
> if (p->reconf_out == 0)
> continue;
> - peer_generate_update(p, re, EVAL_REEVAL, 0);
> + peer_generate_update(p, re, mode);
> }
> adjout_prefix_collect(re->prefix);
> return;
> case EVAL_DEFAULT:
> case EVAL_ALL:
> break;
> + case EVAL_SYNC:
> case EVAL_NONE:
> fatalx("bad eval mode in %s", __func__);
> }
> @@ -354,7 +346,7 @@ peer_process_updates(struct rde_peer *pe
> peer->stats.rib_entry_count--;
>
> RB_FOREACH(p, peer_tree, &peertable)
> - peer_generate_update(p, re, re->pq_mode, 0);
> + peer_generate_update(p, re, re->pq_mode);
>
> adjout_prefix_collect(re->prefix);
> rib_pq_dequeue(re);
> @@ -505,7 +497,7 @@ peer_reaper_upcall(struct pt_entry *pte,
> {
> struct rde_peer *peer = ptr;
>
> - adjout_prefix_withdraw(peer, pte, p);
> + adjout_prefix_withdraw(peer, pte, p, 1);
> }
>
> /*
> @@ -656,7 +648,7 @@ peer_dump_upcall(struct rib_entry *re, v
> /* no eligible prefix, not even for 'evaluate all' */
> return;
>
> - peer_generate_update(peer, re, EVAL_REEVAL, 1);
> + peer_generate_update(peer, re, EVAL_SYNC);
> adjout_prefix_collect(re->prefix);
> }
>
> Index: rde_update.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/rde_update.c,v
> diff -u -p -r1.200 rde_update.c
> --- rde_update.c 13 Jul 2026 12:27:34 -0000 1.200
> +++ rde_update.c 15 Jul 2026 10:00:42 -0000
> @@ -159,7 +159,7 @@ up_enforce_open_policy(struct rde_peer *
> */
> static enum up_state
> up_process_prefix(struct rde_peer *peer, struct prefix *new,
> - struct adjout_prefix *p, int force_update)
> + struct adjout_prefix *p, enum eval_mode mode)
> {
> struct filterstate state;
> struct bgpd_addr addr;
> @@ -202,7 +202,7 @@ up_process_prefix(struct rde_peer *peer,
>
> up_prep_adjout(peer, &state, new->pt->aid);
> adjout_prefix_update(p, peer, &state, new->pt, new_path_id_tx,
> - force_update);
> + mode == EVAL_SYNC);
> rde_filterstate_clean(&state);
>
> /* max prefix checker outbound */
> @@ -221,7 +221,7 @@ up_process_prefix(struct rde_peer *peer,
>
> void
> up_generate_updates(struct rde_peer *peer, struct rib_entry *re,
> - int force_update)
> + enum eval_mode mode)
> {
> struct prefix *new;
> struct adjout_prefix *p;
> @@ -230,7 +230,7 @@ up_generate_updates(struct rde_peer *pee
>
> new = prefix_best(re);
> while (new != NULL) {
> - switch (up_process_prefix(peer, new, p, force_update)) {
> + switch (up_process_prefix(peer, new, p, mode)) {
> case UP_OK:
> case UP_ERR_LIMIT:
> return;
> @@ -249,7 +249,7 @@ up_generate_updates(struct rde_peer *pee
> done:
> /* withdraw prefix */
> if (p != NULL)
> - adjout_prefix_withdraw(peer, re->prefix, p);
> + adjout_prefix_withdraw(peer, re->prefix, p, mode == EVAL_SYNC);
> }
>
> /*
> @@ -261,7 +261,7 @@ done:
> */
> void
> up_generate_addpath(struct rde_peer *peer, struct rib_entry *re,
> - int force_update)
> + enum eval_mode mode)
> {
> struct prefix *new;
> struct adjout_prefix *head, *p;
> @@ -322,8 +322,7 @@ up_generate_addpath(struct rde_peer *pee
> if (extra != 0 && extrapaths >= peer->eval.extrapaths)
> break;
>
> - switch (up_process_prefix(peer, new, (void *)-1,
> - force_update)) {
> + switch (up_process_prefix(peer, new, (void *)-1, mode)) {
> case UP_OK:
> maxpaths++;
> extrapaths += extra;
> @@ -354,7 +353,8 @@ up_generate_addpath(struct rde_peer *pee
> p = adjout_prefix_get(peer, addpath_prefix_list[i],
> re->prefix);
> if (p != NULL)
> - adjout_prefix_withdraw(peer, re->prefix, p);
> + adjout_prefix_withdraw(peer, re->prefix, p,
> + mode == EVAL_SYNC);
> }
> }
> }
> @@ -365,7 +365,7 @@ up_generate_addpath(struct rde_peer *pee
> */
> void
> up_generate_addpath_all(struct rde_peer *peer, struct rib_entry *re,
> - int force_update)
> + enum eval_mode mode)
> {
> #if 0
> /* XXX needs to be rewritten */
> @@ -376,7 +376,7 @@ up_generate_addpath_all(struct rde_peer
> * use up_generate_addpath() for that.
> */
> if (old_pathid_tx == 0 && new == NULL) {
> - up_generate_addpath(peer, re, force_update);
> + up_generate_addpath(peer, re, mode);
> return;
> }
>
> @@ -387,8 +387,7 @@ up_generate_addpath_all(struct rde_peer
>
> if (new != NULL) {
> /* add new path */
> - switch (up_process_prefix(peer, new, (void *)-1,
> - force_update)) {
> + switch (up_process_prefix(peer, new, (void *)-1, mode)) {
> case UP_OK:
> /* don't remove old if an existing prefix was updated */
> if (old_pathid_tx == new->path_id_tx)
> @@ -407,8 +406,11 @@ up_generate_addpath_all(struct rde_peer
> /* withdraw old path */
> p = adjout_prefix_get(peer, old_pathid_tx, re->prefix);
> if (p != NULL)
> - adjout_prefix_withdraw(peer, re->prefix, p);
> + adjout_prefix_withdraw(peer, re->prefix, p,
> + mode == EVAL_SYNC);
> }
> +#else
> + up_generate_addpath(peer, re, mode);
> #endif
> }
>
>
bgpd: rework the force_update logic in adjout