From: Julian Anastasov Date: Fri, 22 Mar 2013 09:46:40 +0000 (+0200) Subject: ipvs: convert lblc scheduler to rcu X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c2a4ffb70eef39;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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: Julian Anastasov Signed-off-by: Simon Horman --- diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c index fdd89b9564ea..b873e177435a 100644 --- a/net/netfilter/ipvs/ip_vs_lblc.c +++ b/net/netfilter/ipvs/ip_vs_lblc.c @@ -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; ibucket[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; ibucket[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; + dest = rcu_dereference(en->dest); + if ((dest->flags & IP_VS_DEST_F_AVAILABLE) && + atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc)) + goto out; } - 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)) - goto out; /* No cache entry or it is invalid, time to schedule */ dest = __ip_vs_lblc_schedule(svc); @@ -517,7 +530,8 @@ 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); - ip_vs_lblc_new(tbl, &iph.daddr, dest); + if (!tbl->dead) + ip_vs_lblc_new(tbl, &iph.daddr, dest); write_unlock(&svc->sched_lock); out: