Nest: Implement locking of prefix tries during walks (5a89edc6) · Commits · 戴 / Bird

nest/route.h

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -191,6 +191,9 @@ typedef struct rtable {
	struct fib_iterator prune_fit; /* Rtable prune FIB iterator */		struct fib_iterator prune_fit; /* Rtable prune FIB iterator */
	struct fib_iterator nhu_fit; /* Next Hop Update FIB iterator */		struct fib_iterator nhu_fit; /* Next Hop Update FIB iterator */
	struct f_trie trie_new; / New prefix trie defined during pruning */		struct f_trie trie_new; / New prefix trie defined during pruning */
			struct f_trie trie_old; / Old prefix trie waiting to be freed */
			u32 trie_lock_count; /* Prefix trie locked by walks */
			u32 trie_old_lock_count; /* Old prefix trie locked by walks */

	list subscribers; /* Subscribers for notifications */		list subscribers; /* Subscribers for notifications */
	struct timer settle_timer; / Settle time for notifications */		struct timer settle_timer; / Settle time for notifications */
	@@ -332,6 +335,8 @@ void rt_preconfig(struct config *);
	void rt_commit(struct config new, struct config old);		void rt_commit(struct config new, struct config old);
	void rt_lock_table(rtable *);		void rt_lock_table(rtable *);
	void rt_unlock_table(rtable *);		void rt_unlock_table(rtable *);
			struct f_trie * rt_lock_trie(rtable *tab);
			void rt_unlock_trie(rtable tab, struct f_trie trie);
	void rt_subscribe(rtable tab, struct rt_subscription s);		void rt_subscribe(rtable tab, struct rt_subscription s);
	void rt_unsubscribe(struct rt_subscription *s);		void rt_unsubscribe(struct rt_subscription *s);
	void rt_flowspec_link(rtable src, rtable dst);		void rt_flowspec_link(rtable src, rtable dst);
	@@ -405,6 +410,7 @@ struct rt_show_data {
	struct rt_show_data_rtable last_table; / Last table in output */		struct rt_show_data_rtable last_table; / Last table in output */
	struct fib_iterator fit; /* Iterator over networks in table */		struct fib_iterator fit; /* Iterator over networks in table */
	struct f_trie_walk_state walk_state; / Iterator over networks in trie */		struct f_trie_walk_state walk_state; / Iterator over networks in trie */
			struct f_trie walk_lock; / Locked trie for walking */
	int verbose, tables_defined_by;		int verbose, tables_defined_by;
	const struct filter *filter;		const struct filter *filter;
	struct proto *show_protocol;		struct proto *show_protocol;

nest/rt-show.c

+9 −0

Original line number	Original line	Diff line number	Diff line
	@@ -222,6 +222,9 @@ rt_show_cleanup(struct cli *c)
	if (d->table_open && !d->trie_walk)		if (d->table_open && !d->trie_walk)
	fit_get(&d->tab->table->fib, &d->fit);		fit_get(&d->tab->table->fib, &d->fit);

			if (d->walk_lock)
			rt_unlock_trie(d->tab->table, d->walk_lock);

	/* Unlock referenced tables */		/* Unlock referenced tables */
	WALK_LIST(tab, d->tables)		WALK_LIST(tab, d->tables)
	rt_unlock_table(tab->table);		rt_unlock_table(tab->table);
	@@ -257,7 +260,10 @@ rt_show_cont(struct cli *c)
	d->walk_state = lp_allocz(c->parser_pool, sizeof (struct f_trie_walk_state));		d->walk_state = lp_allocz(c->parser_pool, sizeof (struct f_trie_walk_state));

	if (d->trie_walk)		if (d->trie_walk)
			{
			d->walk_lock = rt_lock_trie(tab);
	trie_walk_init(d->walk_state, tab->trie, d->addr);		trie_walk_init(d->walk_state, tab->trie, d->addr);
			}
	else		else
	FIB_ITERATE_INIT(&d->fit, &tab->fib);		FIB_ITERATE_INIT(&d->fit, &tab->fib);

	@@ -288,6 +294,9 @@ rt_show_cont(struct cli *c)
	if (!--max)		if (!--max)
	return;		return;
	}		}

			rt_unlock_trie(tab, d->walk_lock);
			d->walk_lock = NULL;
	}		}
	else		else
	{		{

nest/rt-table.c

+80 −2

Original line number	Original line	Diff line number	Diff line
	@@ -2471,7 +2471,19 @@ again:
	if (tab->trie_new)		if (tab->trie_new)
	{		{
	/* Finish prefix trie pruning */		/* Finish prefix trie pruning */

			if (!tab->trie_lock_count)
			{
	rfree(tab->trie->lp);		rfree(tab->trie->lp);
			}
			else
			{
			ASSERT(!tab->trie_old);
			tab->trie_old = tab->trie;
			tab->trie_old_lock_count = tab->trie_lock_count;
			tab->trie_lock_count = 0;
			}

	tab->trie = tab->trie_new;		tab->trie = tab->trie_new;
	tab->trie_new = NULL;		tab->trie_new = NULL;
	tab->prune_trie = 0;		tab->prune_trie = 0;
	@@ -2479,7 +2491,7 @@ again:
	else		else
	{		{
	/* Schedule prefix trie pruning */		/* Schedule prefix trie pruning */
	if (tab->trie && (tab->trie->prefix_count > (2 * tab->fib.entries)))		if (tab->trie && !tab->trie_old && (tab->trie->prefix_count > (2 * tab->fib.entries)))
	{		{
	/* state change 0->1, 2->3 */		/* state change 0->1, 2->3 */
	tab->prune_state \|= 1;		tab->prune_state \|= 1;
	@@ -2504,6 +2516,72 @@ again:
	return;		return;
	}		}

			/**
			* rt_lock_trie - lock a prefix trie of a routing table
			* @tab: routing table with prefix trie to be locked
			*
			* The prune loop may rebuild the prefix trie and invalidate f_trie_walk_state
			* structures. Therefore, asynchronous walks should lock the prefix trie using
			* this function. That allows the prune loop to rebuild the trie, but postpones
			* its freeing until all walks are done (unlocked by rt_unlock_trie()).
			*
			* Return a current trie that will be locked, the value should be passed back to
			* rt_unlock_trie() for unlocking.
			*
			*/
			struct f_trie *
			rt_lock_trie(rtable *tab)
			{
			ASSERT(tab->trie);

			tab->trie_lock_count++;
			return tab->trie;
			}

			/**
			* rt_unlock_trie - unlock a prefix trie of a routing table
			* @tab: routing table with prefix trie to be locked
			* @trie: value returned by matching rt_lock_trie()
			*
			* Done for trie locked by rt_lock_trie() after walk over the trie is done.
			* It may free the trie and schedule next trie pruning.
			*/
			void
			rt_unlock_trie(rtable tab, struct f_trie trie)
			{
			ASSERT(trie);

			if (trie == tab->trie)
			{
			/* Unlock the current prefix trie */
			ASSERT(tab->trie_lock_count);
			tab->trie_lock_count--;
			}
			else if (trie == tab->trie_old)
			{
			/* Unlock the old prefix trie */
			ASSERT(tab->trie_old_lock_count);
			tab->trie_old_lock_count--;

			/* Free old prefix trie that is no longer needed */
			if (!tab->trie_old_lock_count)
			{
			rfree(tab->trie_old->lp);
			tab->trie_old = NULL;

			/* Kick prefix trie pruning that was postponed */
			if (tab->trie && (tab->trie->prefix_count > (2 * tab->fib.entries)))
			{
			tab->prune_trie = 1;
			rt_schedule_prune(tab);
			}
			}
			}
			else
			log(L_BUG "Invalid arg to rt_unlock_trie()");
			}


	void		void
	rt_preconfig(struct config *c)		rt_preconfig(struct config *c)
	{		{

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