bfdd: support global BFD reset

Add command 'no bfd' to remove all BFD sessions configuration and fix
other daemon integration.

Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>

bfdd/bfd.c

@@ -1290,6 +1290,7 @@ static unsigned int bfd_key_hash_do(const void *p);
 static void _bfd_free(struct hash_bucket *hb,
 		      void *arg __attribute__((__unused__)));
 int _bfd_session_next(struct hash_bucket *hb, void *arg);
+void _bfd_session_remove_manual(struct hash_bucket *hb, void *arg);
 
 /* BFD hash for our discriminator. */
 static unsigned int bfd_id_hash_do(const void *p)
@@ -1587,6 +1588,35 @@ const struct bfd_session *bfd_session_next(const struct bfd_session *bs,
 	return bsi.bsi_bs;
 }
 
+void _bfd_session_remove_manual(struct hash_bucket *hb,
+				void *arg __attribute__((__unused__)))
+{
+	struct bfd_session *bs = hb->data;
+
+	/* Delete only manually configured sessions. */
+	if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG) == 0)
+		return;
+
+	bs->refcount--;
+	BFD_UNSET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+
+	/* Don't delete sessions still in use. */
+	if (bs->refcount != 0)
+		return;
+
+	bfd_session_free(bs);
+}
+
+/*
+ * bfd_sessions_remove_manual: remove all manually configured sessions.
+ *
+ * NOTE: this function doesn't remove automatically created sessions.
+ */
+void bfd_sessions_remove_manual(void)
+{
+	hash_iterate(bfd_key_hash, _bfd_session_remove_manual, NULL);
+}
+
 /*
  * VRF related functions.
  */

bfdd/bfd.h

@@ -550,6 +550,7 @@ struct bfd_session *bs_registrate(struct bfd_session *bs);
 void bfd_session_free(struct bfd_session *bs);
 const struct bfd_session *bfd_session_next(const struct bfd_session *bs,
 					   bool mhop);
+void bfd_sessions_remove_manual(void);
 
 /* BFD hash data structures interface */
 void bfd_initialize(void);

bfdd/bfdd_cli.c

@@ -52,6 +52,16 @@
 /*
  * Functions.
  */
+DEFUN(
+	bfd_config_reset, bfd_config_reset_cmd,
+	"no bfd",
+	NO_STR
+	"Configure BFD peers\n")
+{
+	nb_cli_enqueue_change(vty, "/frr-bfdd:bfdd/bfd", NB_OP_DESTROY, NULL);
+	return nb_cli_apply_changes(vty, NULL);
+}
+
 void bfd_cli_show_header(struct vty *vty,
 			 struct lyd_node *dnode __attribute__((__unused__)),
 			 bool show_defaults __attribute__((__unused__)))
@@ -343,6 +353,8 @@ void bfd_cli_show_echo_interval(struct vty *vty, struct lyd_node *dnode,
 void
 bfdd_cli_init(void)
 {
+	install_element(CONFIG_NODE, &bfd_config_reset_cmd);
+
 	install_element(BFD_NODE, &bfd_peer_enter_cmd);
 	install_element(BFD_NODE, &bfd_no_peer_cmd);
 

bfdd/bfdd_northbound.c

@@ -71,11 +71,27 @@ int bfd_session_create(enum nb_event event, const struct lyd_node *dnode,
 	switch (event) {
 	case NB_EV_VALIDATE:
 		bfd_session_get_key(mhop, dnode, &bk);
-		if (bfd_key_lookup(bk))
+		bs = bfd_key_lookup(bk);
+
+		/* This session was already configured by CLI. */
+		if (bs != NULL && BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG))
 			return NB_ERR_VALIDATION;
 		break;
 
 	case NB_EV_PREPARE:
+		bfd_session_get_key(mhop, dnode, &bk);
+		bs = bfd_key_lookup(bk);
+
+		/* This session was already configured by another daemon. */
+		if (bs != NULL) {
+			/* Now it is configured also by CLI. */
+			BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+			bs->refcount++;
+
+			resource->ptr = bs;
+			break;
+		}
+
 		bs = bfd_session_new();
 		if (bs == NULL)
 			return NB_ERR_RESOURCE;
@@ -84,6 +100,7 @@ int bfd_session_create(enum nb_event event, const struct lyd_node *dnode,
 		bfd_session_get_key(mhop, dnode, &bs->key);
 
 		/* Set configuration flags. */
+		bs->refcount = 1;
 		BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
 		if (mhop)
 			BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_MH);
@@ -95,13 +112,17 @@ int bfd_session_create(enum nb_event event, const struct lyd_node *dnode,
 
 	case NB_EV_APPLY:
 		bs = resource->ptr;
-		if (bs_registrate(bs) == NULL)
+
+		/* Only attempt to registrate if freshly allocated. */
+		if (bs->discrs.my_discr == 0 && bs_registrate(bs) == NULL)
 			return NB_ERR_RESOURCE;
 
 		nb_running_set_entry(dnode, bs);
 		break;
 
 	case NB_EV_ABORT:
+		bs = resource->ptr;
+		if (bs->refcount <= 1)
 			bfd_session_free(resource->ptr);
 		break;
 	}
@@ -112,6 +133,7 @@ int bfd_session_create(enum nb_event event, const struct lyd_node *dnode,
 int bfd_session_destroy(enum nb_event event, const struct lyd_node *dnode,
 			bool mhop)
 {
+	struct bfd_session *bs;
 	struct bfd_key bk;
 
 	switch (event) {
@@ -126,7 +148,18 @@ int bfd_session_destroy(enum nb_event event, const struct lyd_node *dnode,
 		break;
 
 	case NB_EV_APPLY:
-		bfd_session_free(nb_running_unset_entry(dnode));
+		bs = nb_running_unset_entry(dnode);
+		/* CLI is not using this session anymore. */
+		if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG) == 0)
+			break;
+
+		BFD_UNSET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+		bs->refcount--;
+		/* There are still daemons using it. */
+		if (bs->refcount > 0)
+			break;
+
+		bfd_session_free(bs);
 		break;
 
 	case NB_EV_ABORT:
@@ -152,8 +185,25 @@ static int bfdd_bfd_create(enum nb_event event,
 
 static int bfdd_bfd_destroy(enum nb_event event, const struct lyd_node *dnode)
 {
+	switch (event) {
+	case NB_EV_VALIDATE:
 		/* NOTHING */
 		return NB_OK;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		bfd_sessions_remove_manual();
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		return NB_OK;
+	}
+
+	return NB_OK;
 }
 
 /*