Nest: Fix race condition during reconfiguration (a81e18da) · Commits · 戴 / Bird

nest/proto.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -165,6 +165,7 @@ proto_add_channel(struct proto p, struct channel_config cf)
		c->channel_state = CS_DOWN;
		c->export_state = ES_DOWN;
		c->last_state_change = current_time();
		c->last_tx_filter_change = current_time();
		c->reloadable = 1;

		CALL(c->channel->init, c, cf);
		@@ -557,6 +558,9 @@ channel_reconfigure(struct channel c, struct channel_config cf)

		channel_verify_limits(c);

		if (export_changed)
		c->last_tx_filter_change = current_time();

		/* Execute channel-specific reconfigure hook */
		if (c->channel->reconfigure && !c->channel->reconfigure(c, cf))
		return 0;

nest/protocol.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -536,6 +536,7 @@ struct channel {
		u8 gr_wait; /* Route export to channel is postponed until graceful restart */

		btime last_state_change; /* Time of last state transition */
		btime last_tx_filter_change;
		};

nest/rt-table.c

+15 −15

Original line number	Diff line number	Diff line
		@@ -549,29 +549,29 @@ rt_notify_basic(struct channel c, net net, rte new0, rte old0, int refeed)
		c->stats.exp_withdraws_received++;

		/*
		* This is a tricky part - we don't know whether route 'old' was
		* exported to protocol 'p' or was filtered by the export filter.
		* We try to run the export filter to know this to have a correct
		* value in 'old' argument of rte_update (and proper filter value)
		* This is a tricky part - we don't know whether route 'old' was exported to
		* protocol 'p' or was filtered by the export filter. We try to run the export
		* filter to know this to have a correct value in 'old' argument of rte_update
		* (and proper filter value).
		*
		* FIXME - this is broken because 'configure soft' may change
		* filters but keep routes. Refeed is expected to be called after
		* change of the filters and with old == new, therefore we do not
		* even try to run the filter on an old route, This may lead to
		* 'spurious withdraws' but ensure that there are no 'missing
		* This is broken because 'configure soft' may change filters but keep routes.
		* Refeed cycle is expected to be called after change of the filters and with
		* old == new, therefore we do not even try to run the filter on an old route.
		* This may lead to 'spurious withdraws' but ensure that there are no 'missing
		* withdraws'.
		*
		* This is not completely safe as there is a window between
		* reconfiguration and the end of refeed - if a newly filtered
		* route disappears during this period, proper withdraw is not
		* sent (because old would be also filtered) and the route is
		* not refeeded (because it disappeared before that).
		* This is not completely safe as there is a window between reconfiguration
		* and the end of refeed - if a newly filtered route disappears during this
		* period, proper withdraw is not sent (because old would be also filtered)
		* and the route is not refeeded (because it disappeared before that).
		* Therefore, we also do not try to run the filter on old routes that are
		* older than the last filter change.
		*/

		if (new)
		new = export_filter(c, new, &new_free, 0);

		if (old && !refeed)
		if (old && !(refeed \|\| (old->lastmod <= c->last_tx_filter_change)))
		old = export_filter(c, old, &old_free, 1);

		if (!new && !old)

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