ipvs: preparations for using rcu in schedulers

Allow schedulers to use rcu_dereference when returning destination on lookup. The RCU read-side critical section will allow ip_vs_bind_dest to get dest refcnt as preparation for the step where destinations will be deleted without an IP_VS_WAIT_WHILE guard that holds the packet processing during update. Add new optional scheduler methods add_dest, del_dest and upd_dest. For now the methods are called together with update_service but update_service will be removed in a following change. Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>

ipvs: preparations for using rcu in schedulers
Allow schedulers to use rcu_dereference when returning destination on lookup. The RCU read-side critical section will allow ip_vs_bind_dest to get dest refcnt as preparation for the step where destinations will be deleted without an IP_VS_WAIT_WHILE guard that holds the packet processing during update. Add new optional scheduler methods add_dest, del_dest and upd_dest. For now the methods are called together with update_service but update_service will be removed in a following change. Signed-off-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Simon Horman <horms@verge.net.au>
Julian Anastasov · Pablo Neira Ayuso
1 parent 71dfa982f1
Showing 3 changed files with 20 additions and 0 deletions Side-by-side Diff
include/net/ip_vs.h
net/netfilter/ipvs/ip_vs_core.c
net/netfilter/ipvs/ip_vs_ctl.c
@@ -805,6 +805,12 @@
 	int (*done_service)(struct ip_vs_service *svc);
 	/* scheduler updating service */
 	int (*update_service)(struct ip_vs_service *svc);
+	/* dest is linked */
+	int (*add_dest)(struct ip_vs_service *svc, struct ip_vs_dest *dest);
+	/* dest is unlinked */
+	int (*del_dest)(struct ip_vs_service *svc, struct ip_vs_dest *dest);
+	/* dest is updated */
+	int (*upd_dest)(struct ip_vs_service *svc, struct ip_vs_dest *dest);
  
 	/* selecting a server from the given service */
 	struct ip_vs_dest* (*schedule)(struct ip_vs_service *svc,
@@ -301,8 +301,10 @@
 		 * template is not available.
 		 * return *ignored=0 i.e. ICMP and NF_DROP
 		 */
+		rcu_read_lock();
 		dest = svc->scheduler->schedule(svc, skb);
 		if (!dest) {
+			rcu_read_unlock();
 			IP_VS_DBG(1, "p-schedule: no dest found.\n");
 			kfree(param.pe_data);
 			*ignored = 0;
@@ -318,6 +320,7 @@
 		 * when the template expires */
 		ct = ip_vs_conn_new(&param, &dest->addr, dport,
 				    IP_VS_CONN_F_TEMPLATE, dest, skb->mark);
+		rcu_read_unlock();
 		if (ct == NULL) {
 			kfree(param.pe_data);
 			*ignored = -1;
  
@@ -446,8 +449,10 @@
 		return NULL;
 	}
  
+	rcu_read_lock();
 	dest = svc->scheduler->schedule(svc, skb);
 	if (dest == NULL) {
+		rcu_read_unlock();
 		IP_VS_DBG(1, "Schedule: no dest found.\n");
 		return NULL;
 	}
@@ -468,6 +473,7 @@
 		cp = ip_vs_conn_new(&p, &dest->addr,
 				    dest->port ? dest->port : pptr[1],
 				    flags, dest, skb->mark);
+		rcu_read_unlock();
 		if (!cp) {
 			*ignored = -1;
 			return NULL;
@@ -825,6 +825,11 @@
 	if (add) {
 		list_add(&dest->n_list, &svc->destinations);
 		svc->num_dests++;
+		if (svc->scheduler->add_dest)
+			svc->scheduler->add_dest(svc, dest);
+	} else {
+		if (svc->scheduler->upd_dest)
+			svc->scheduler->upd_dest(svc, dest);
 	}
  
 	/* call the update_service, because server weight may be changed */
@@ -1070,6 +1075,9 @@
 	 */
 	list_del(&dest->n_list);
 	svc->num_dests--;
+
+	if (svcupd && svc->scheduler->del_dest)
+		svc->scheduler->del_dest(svc, dest);
  
 	/*
 	 *  Call the update_service function of its scheduler
...	...	@@ -805,6 +805,12 @@
805	805	int (done_service)(struct ip_vs_service svc);
806	806	/* scheduler updating service */
807	807	int (update_service)(struct ip_vs_service svc);
	808	+ /* dest is linked */
	809	+ int (add_dest)(struct ip_vs_service svc, struct ip_vs_dest *dest);
	810	+ /* dest is unlinked */
	811	+ int (del_dest)(struct ip_vs_service svc, struct ip_vs_dest *dest);
	812	+ /* dest is updated */
	813	+ int (upd_dest)(struct ip_vs_service svc, struct ip_vs_dest *dest);
808	814
809	815	/* selecting a server from the given service */
810	816	struct ip_vs_dest* (schedule)(struct ip_vs_service svc,
...	...	@@ -301,8 +301,10 @@
301	301	* template is not available.
302	302	* return *ignored=0 i.e. ICMP and NF_DROP
303	303	*/
	304	+ rcu_read_lock();
304	305	dest = svc->scheduler->schedule(svc, skb);
305	306	if (!dest) {
	307	+ rcu_read_unlock();
306	308	IP_VS_DBG(1, "p-schedule: no dest found.\n");
307	309	kfree(param.pe_data);
308	310	*ignored = 0;
...	...	@@ -318,6 +320,7 @@
318	320	* when the template expires */
319	321	ct = ip_vs_conn_new(&param, &dest->addr, dport,
320	322	IP_VS_CONN_F_TEMPLATE, dest, skb->mark);
	323	+ rcu_read_unlock();
321	324	if (ct == NULL) {
322	325	kfree(param.pe_data);
323	326	*ignored = -1;
324	327
...	...	@@ -446,8 +449,10 @@
446	449	return NULL;
447	450	}
448	451
	452	+ rcu_read_lock();
449	453	dest = svc->scheduler->schedule(svc, skb);
450	454	if (dest == NULL) {
	455	+ rcu_read_unlock();
451	456	IP_VS_DBG(1, "Schedule: no dest found.\n");
452	457	return NULL;
453	458	}
...	...	@@ -468,6 +473,7 @@
468	473	cp = ip_vs_conn_new(&p, &dest->addr,
469	474	dest->port ? dest->port : pptr[1],
470	475	flags, dest, skb->mark);
	476	+ rcu_read_unlock();
471	477	if (!cp) {
472	478	*ignored = -1;
473	479	return NULL;
...	...	@@ -825,6 +825,11 @@
825	825	if (add) {
826	826	list_add(&dest->n_list, &svc->destinations);
827	827	svc->num_dests++;
	828	+ if (svc->scheduler->add_dest)
	829	+ svc->scheduler->add_dest(svc, dest);
	830	+ } else {
	831	+ if (svc->scheduler->upd_dest)
	832	+ svc->scheduler->upd_dest(svc, dest);
828	833	}
829	834
830	835	/* call the update_service, because server weight may be changed */
...	...	@@ -1070,6 +1075,9 @@
1070	1075	*/
1071	1076	list_del(&dest->n_list);
1072	1077	svc->num_dests--;
	1078	+
	1079	+ if (svcupd && svc->scheduler->del_dest)
	1080	+ svc->scheduler->del_dest(svc, dest);
1073	1081
1074	1082	/*
1075	1083	* Call the update_service function of its scheduler