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Commit c2a4ffb7 authored by Julian Anastasov's avatar Julian Anastasov Committed by Pablo Neira Ayuso
Browse files

ipvs: convert lblc scheduler to rcu 



The schedule method now needs _rcu list-traversal
primitive for svc->destinations. The read_lock for sched_lock is
removed. Use a dead flag to prevent new entries to be created
while scheduler is reclaimed. Use hlist for the hash table.

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
parent 8f3d0023

net/netfilter/ipvs/ip_vs_lblc.c

+55 −41
Original line number Diff line number Diff line
@@ -90,11 +90,12 @@ 
 *      IP address and its destination server

 */

struct ip_vs_lblc_entry {

	struct list_head        list;

	struct hlist_node	list;

	int			af;		/* address family */

	union nf_inet_addr      addr;           /* destination IP address */

	struct ip_vs_dest       *dest;          /* real server (cache) */

	struct ip_vs_dest __rcu	*dest;          /* real server (cache) */

	unsigned long           lastuse;        /* last used time */

	struct rcu_head		rcu_head;

};
@@ -102,12 +103,14 @@ struct ip_vs_lblc_entry { 
 *      IPVS lblc hash table

 */

struct ip_vs_lblc_table {

	struct list_head        bucket[IP_VS_LBLC_TAB_SIZE];  /* hash bucket */

	struct rcu_head		rcu_head;

	struct hlist_head __rcu bucket[IP_VS_LBLC_TAB_SIZE];  /* hash bucket */

	struct timer_list       periodic_timer; /* collect stale entries */

	atomic_t                entries;        /* number of entries */

	int                     max_size;       /* maximum size of entries */

	struct timer_list       periodic_timer; /* collect stale entries */

	int                     rover;          /* rover for expire check */

	int                     counter;        /* counter for no expire */

	bool			dead;

};
@@ -129,13 +132,16 @@ static ctl_table vs_vars_table[] = { 


static inline void ip_vs_lblc_free(struct ip_vs_lblc_entry *en)

{

	list_del(&en->list);

	struct ip_vs_dest *dest;



	hlist_del_rcu(&en->list);

	/*

	 * We don't kfree dest because it is referred either by its service

	 * or the trash dest list.

	 */

	atomic_dec(&en->dest->refcnt);

	kfree(en);

	dest = rcu_dereference_protected(en->dest, 1);

	ip_vs_dest_put(dest);

	kfree_rcu(en, rcu_head);

}
@@ -165,15 +171,12 @@ ip_vs_lblc_hash(struct ip_vs_lblc_table *tbl, struct ip_vs_lblc_entry *en) 
{

	unsigned int hash = ip_vs_lblc_hashkey(en->af, &en->addr);



	list_add(&en->list, &tbl->bucket[hash]);

	hlist_add_head_rcu(&en->list, &tbl->bucket[hash]);

	atomic_inc(&tbl->entries);

}





/*

 *  Get ip_vs_lblc_entry associated with supplied parameters. Called under read

 *  lock

 */

/* Get ip_vs_lblc_entry associated with supplied parameters. */

static inline struct ip_vs_lblc_entry *

ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl,

	       const union nf_inet_addr *addr)
@@ -181,7 +184,7 @@ ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl, 
	unsigned int hash = ip_vs_lblc_hashkey(af, addr);

	struct ip_vs_lblc_entry *en;



	list_for_each_entry(en, &tbl->bucket[hash], list)

	hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list)

		if (ip_vs_addr_equal(af, &en->addr, addr))

			return en;
@@ -209,14 +212,20 @@ ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr, 
		ip_vs_addr_copy(dest->af, &en->addr, daddr);

		en->lastuse = jiffies;



		atomic_inc(&dest->refcnt);

		en->dest = dest;

		ip_vs_dest_hold(dest);

		RCU_INIT_POINTER(en->dest, dest);



		ip_vs_lblc_hash(tbl, en);

	} else if (en->dest != dest) {

		atomic_dec(&en->dest->refcnt);

		atomic_inc(&dest->refcnt);

		en->dest = dest;

	} else {

		struct ip_vs_dest *old_dest;



		old_dest = rcu_dereference_protected(en->dest, 1);

		if (old_dest != dest) {

			ip_vs_dest_put(old_dest);

			ip_vs_dest_hold(dest);

			/* No ordering constraints for refcnt */

			RCU_INIT_POINTER(en->dest, dest);

		}

	}



	return en;
@@ -226,17 +235,22 @@ ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr, 
/*

 *      Flush all the entries of the specified table.

 */

static void ip_vs_lblc_flush(struct ip_vs_lblc_table *tbl)

static void ip_vs_lblc_flush(struct ip_vs_service *svc)

{

	struct ip_vs_lblc_entry *en, *nxt;

	struct ip_vs_lblc_table *tbl = svc->sched_data;

	struct ip_vs_lblc_entry *en;

	struct hlist_node *next;

	int i;



	write_lock_bh(&svc->sched_lock);

	tbl->dead = 1;

	for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {

		list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {

		hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) {

			ip_vs_lblc_free(en);

			atomic_dec(&tbl->entries);

		}

	}

	write_unlock_bh(&svc->sched_lock);

}



static int sysctl_lblc_expiration(struct ip_vs_service *svc)
@@ -252,7 +266,8 @@ static int sysctl_lblc_expiration(struct ip_vs_service *svc) 
static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc)

{

	struct ip_vs_lblc_table *tbl = svc->sched_data;

	struct ip_vs_lblc_entry *en, *nxt;

	struct ip_vs_lblc_entry *en;

	struct hlist_node *next;

	unsigned long now = jiffies;

	int i, j;
@@ -260,7 +275,7 @@ static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc) 
		j = (j + 1) & IP_VS_LBLC_TAB_MASK;



		write_lock(&svc->sched_lock);

		list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {

		hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {

			if (time_before(now,

					en->lastuse +

					sysctl_lblc_expiration(svc)))
@@ -293,7 +308,8 @@ static void ip_vs_lblc_check_expire(unsigned long data) 
	unsigned long now = jiffies;

	int goal;

	int i, j;

	struct ip_vs_lblc_entry *en, *nxt;

	struct ip_vs_lblc_entry *en;

	struct hlist_node *next;



	if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {

		/* do full expiration check */
@@ -315,7 +331,7 @@ static void ip_vs_lblc_check_expire(unsigned long data) 
		j = (j + 1) & IP_VS_LBLC_TAB_MASK;



		write_lock(&svc->sched_lock);

		list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {

		hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {

			if (time_before(now, en->lastuse + ENTRY_TIMEOUT))

				continue;
@@ -354,11 +370,12 @@ static int ip_vs_lblc_init_svc(struct ip_vs_service *svc) 
	 *    Initialize the hash buckets

	 */

	for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {

		INIT_LIST_HEAD(&tbl->bucket[i]);

		INIT_HLIST_HEAD(&tbl->bucket[i]);

	}

	tbl->max_size = IP_VS_LBLC_TAB_SIZE*16;

	tbl->rover = 0;

	tbl->counter = 1;

	tbl->dead = 0;



	/*

	 *    Hook periodic timer for garbage collection
@@ -379,10 +396,10 @@ static int ip_vs_lblc_done_svc(struct ip_vs_service *svc) 
	del_timer_sync(&tbl->periodic_timer);



	/* got to clean up table entries here */

	ip_vs_lblc_flush(tbl);

	ip_vs_lblc_flush(svc);



	/* release the table itself */

	kfree(tbl);

	kfree_rcu(tbl, rcu_head);

	IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n",

		  sizeof(*tbl));
@@ -408,7 +425,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service *svc) 
	 * The server with weight=0 is quiesced and will not receive any

	 * new connection.

	 */

	list_for_each_entry(dest, &svc->destinations, n_list) {

	list_for_each_entry_rcu(dest, &svc->destinations, n_list) {

		if (dest->flags & IP_VS_DEST_F_OVERLOAD)

			continue;

		if (atomic_read(&dest->weight) > 0) {
@@ -423,7 +440,7 @@ __ip_vs_lblc_schedule(struct ip_vs_service *svc) 
	 *    Find the destination with the least load.

	 */

  nextstage:

	list_for_each_entry_continue(dest, &svc->destinations, n_list) {

	list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) {

		if (dest->flags & IP_VS_DEST_F_OVERLOAD)

			continue;
@@ -457,7 +474,7 @@ is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc) 
	if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {

		struct ip_vs_dest *d;



		list_for_each_entry(d, &svc->destinations, n_list) {

		list_for_each_entry_rcu(d, &svc->destinations, n_list) {

			if (atomic_read(&d->activeconns)*2

			    < atomic_read(&d->weight)) {

				return 1;
@@ -484,7 +501,6 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) 
	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);



	/* First look in our cache */

	read_lock(&svc->sched_lock);

	en = ip_vs_lblc_get(svc->af, tbl, &iph.daddr);

	if (en) {

		/* We only hold a read lock, but this is atomic */
@@ -499,14 +515,11 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) 
		 * free up entries from the trash at any time.

		 */



		if (en->dest->flags & IP_VS_DEST_F_AVAILABLE)

			dest = en->dest;

	}

	read_unlock(&svc->sched_lock);



	/* If the destination has a weight and is not overloaded, use it */

	if (dest && atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc))

		dest = rcu_dereference(en->dest);

		if ((dest->flags & IP_VS_DEST_F_AVAILABLE) &&

		    atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc))

			goto out;

	}



	/* No cache entry or it is invalid, time to schedule */

	dest = __ip_vs_lblc_schedule(svc);
@@ -517,6 +530,7 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) 


	/* If we fail to create a cache entry, we'll just use the valid dest */

	write_lock(&svc->sched_lock);

	if (!tbl->dead)

		ip_vs_lblc_new(tbl, &iph.daddr, dest);

	write_unlock(&svc->sched_lock);