// SPDX-License-Identifier: GPL-2.0-or-later /* * IPVS: Locality-Based Least-Connection scheduling module * * Authors: Wensong Zhang * * Changes: * Martin Hamilton : fixed the terrible locking bugs * *lock(tbl->lock) ==> *lock(&tbl->lock) * Wensong Zhang : fixed the uninitialized tbl->lock bug * Wensong Zhang : added doing full expiration check to * collect stale entries of 24+ hours when * no partial expire check in a half hour * Julian Anastasov : replaced del_timer call with del_timer_sync * to avoid the possible race between timer * handler and del_timer thread in SMP */ /* * The lblc algorithm is as follows (pseudo code): * * if cachenode[dest_ip] is null then * n, cachenode[dest_ip] <- {weighted least-conn node}; * else * n <- cachenode[dest_ip]; * if (n is dead) OR * (n.conns>n.weight AND * there is a node m with m.conns #include #include #include #include #include #include /* for sysctl */ #include #include #include /* * It is for garbage collection of stale IPVS lblc entries, * when the table is full. */ #define CHECK_EXPIRE_INTERVAL (60*HZ) #define ENTRY_TIMEOUT (6*60*HZ) #define DEFAULT_EXPIRATION (24*60*60*HZ) /* * It is for full expiration check. * When there is no partial expiration check (garbage collection) * in a half hour, do a full expiration check to collect stale * entries that haven't been touched for a day. */ #define COUNT_FOR_FULL_EXPIRATION 30 /* * for IPVS lblc entry hash table */ #ifndef CONFIG_IP_VS_LBLC_TAB_BITS #define CONFIG_IP_VS_LBLC_TAB_BITS 10 #endif #define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS #define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS) #define IP_VS_LBLC_TAB_MASK (IP_VS_LBLC_TAB_SIZE - 1) /* * IPVS lblc entry represents an association between destination * IP address and its destination server */ struct ip_vs_lblc_entry { struct hlist_node list; int af; /* address family */ union nf_inet_addr addr; /* destination IP address */ struct ip_vs_dest *dest; /* real server (cache) */ unsigned long lastuse; /* last used time */ struct rcu_head rcu_head; }; /* * IPVS lblc hash table */ struct ip_vs_lblc_table { struct rcu_head rcu_head; struct hlist_head bucket[IP_VS_LBLC_TAB_SIZE]; /* hash bucket */ struct timer_list periodic_timer; /* collect stale entries */ struct ip_vs_service *svc; /* pointer back to service */ atomic_t entries; /* number of entries */ int max_size; /* maximum size of entries */ int rover; /* rover for expire check */ int counter; /* counter for no expire */ bool dead; }; /* * IPVS LBLC sysctl table */ #ifdef CONFIG_SYSCTL static struct ctl_table vs_vars_table[] = { { .procname = "lblc_expiration", .data = NULL, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_jiffies, }, { } }; #endif static void ip_vs_lblc_rcu_free(struct rcu_head *head) { struct ip_vs_lblc_entry *en = container_of(head, struct ip_vs_lblc_entry, rcu_head); ip_vs_dest_put_and_free(en->dest); kfree(en); } static inline void ip_vs_lblc_del(struct ip_vs_lblc_entry *en) { hlist_del_rcu(&en->list); call_rcu(&en->rcu_head, ip_vs_lblc_rcu_free); } /* * Returns hash value for IPVS LBLC entry */ static inline unsigned int ip_vs_lblc_hashkey(int af, const union nf_inet_addr *addr) { __be32 addr_fold = addr->ip; #ifdef CONFIG_IP_VS_IPV6 if (af == AF_INET6) addr_fold = addr->ip6[0]^addr->ip6[1]^ addr->ip6[2]^addr->ip6[3]; #endif return hash_32(ntohl(addr_fold), IP_VS_LBLC_TAB_BITS); } /* * Hash an entry in the ip_vs_lblc_table. * returns bool success. */ static void 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); hlist_add_head_rcu(&en->list, &tbl->bucket[hash]); atomic_inc(&tbl->entries); } /* 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) { unsigned int hash = ip_vs_lblc_hashkey(af, addr); struct ip_vs_lblc_entry *en; hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list) if (ip_vs_addr_equal(af, &en->addr, addr)) return en; return NULL; } /* * Create or update an ip_vs_lblc_entry, which is a mapping of a destination IP * address to a server. Called under spin lock. */ static inline struct ip_vs_lblc_entry * ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr, u16 af, struct ip_vs_dest *dest) { struct ip_vs_lblc_entry *en; en = ip_vs_lblc_get(af, tbl, daddr); if (en) { if (en->dest == dest) return en; ip_vs_lblc_del(en); } en = kmalloc(sizeof(*en), GFP_ATOMIC); if (!en) return NULL; en->af = af; ip_vs_addr_copy(af, &en->addr, daddr); en->lastuse = jiffies; ip_vs_dest_hold(dest); en->dest = dest; ip_vs_lblc_hash(tbl, en); return en; } /* * Flush all the entries of the specified table. */ static void ip_vs_lblc_flush(struct ip_vs_service *svc) { struct ip_vs_lblc_table *tbl = svc->sched_data; struct ip_vs_lblc_entry *en; struct hlist_node *next; int i; spin_lock_bh(&svc->sched_lock); tbl->dead = true; for (i = 0; i < IP_VS_LBLC_TAB_SIZE; i++) { hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) { ip_vs_lblc_del(en); atomic_dec(&tbl->entries); } } spin_unlock_bh(&svc->sched_lock); } static int sysctl_lblc_expiration(struct ip_vs_service *svc) { #ifdef CONFIG_SYSCTL return svc->ipvs->sysctl_lblc_expiration; #else return DEFAULT_EXPIRATION; #endif } 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; struct hlist_node *next; unsigned long now = jiffies; int i, j; for (i = 0, j = tbl->rover; i < IP_VS_LBLC_TAB_SIZE; i++) { j = (j + 1) & IP_VS_LBLC_TAB_MASK; spin_lock(&svc->sched_lock); hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) { if (time_before(now, en->lastuse + sysctl_lblc_expiration(svc))) continue; ip_vs_lblc_del(en); atomic_dec(&tbl->entries); } spin_unlock(&svc->sched_lock); } tbl->rover = j; } /* * Periodical timer handler for IPVS lblc table * It is used to collect stale entries when the number of entries * exceeds the maximum size of the table. * * Fixme: we probably need more complicated algorithm to collect * entries that have not been used for a long time even * if the number of entries doesn't exceed the maximum size * of the table. * The full expiration check is for this purpose now. */ static void ip_vs_lblc_check_expire(struct timer_list *t) { struct ip_vs_lblc_table *tbl = from_timer(tbl, t, periodic_timer); struct ip_vs_service *svc = tbl->svc; unsigned long now = jiffies; int goal; int i, j; struct ip_vs_lblc_entry *en; struct hlist_node *next; if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) { /* do full expiration check */ ip_vs_lblc_full_check(svc); tbl->counter = 1; goto out; } if (atomic_read(&tbl->entries) <= tbl->max_size) { tbl->counter++; goto out; } goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3; if (goal > tbl->max_size/2) goal = tbl->max_size/2; for (i = 0, j = tbl->rover; i < IP_VS_LBLC_TAB_SIZE; i++) { j = (j + 1) & IP_VS_LBLC_TAB_MASK; spin_lock(&svc->sched_lock); hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) { if (time_before(now, en->lastuse + ENTRY_TIMEOUT)) continue; ip_vs_lblc_del(en); atomic_dec(&tbl->entries); goal--; } spin_unlock(&svc->sched_lock); if (goal <= 0) break; } tbl->rover = j; out: mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL); } static int ip_vs_lblc_init_svc(struct ip_vs_service *svc) { int i; struct ip_vs_lblc_table *tbl; /* * Allocate the ip_vs_lblc_table for this service */ tbl = kmalloc(sizeof(*tbl), GFP_KERNEL); if (tbl == NULL) return -ENOMEM; svc->sched_data = tbl; IP_VS_DBG(6, "LBLC hash table (memory=%zdbytes) allocated for " "current service\n", sizeof(*tbl)); /* * Initialize the hash buckets */ for (i = 0; i < IP_VS_LBLC_TAB_SIZE; i++) { INIT_HLIST_HEAD(&tbl->bucket[i]); } tbl->max_size = IP_VS_LBLC_TAB_SIZE*16; tbl->rover = 0; tbl->counter = 1; tbl->dead = false; tbl->svc = svc; atomic_set(&tbl->entries, 0); /* * Hook periodic timer for garbage collection */ timer_setup(&tbl->periodic_timer, ip_vs_lblc_check_expire, 0); mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL); return 0; } static void ip_vs_lblc_done_svc(struct ip_vs_service *svc) { struct ip_vs_lblc_table *tbl = svc->sched_data; /* remove periodic timer */ timer_shutdown_sync(&tbl->periodic_timer); /* got to clean up table entries here */ ip_vs_lblc_flush(svc); /* release the table itself */ kfree_rcu(tbl, rcu_head); IP_VS_DBG(6, "LBLC hash table (memory=%zdbytes) released\n", sizeof(*tbl)); } static inline struct ip_vs_dest * __ip_vs_lblc_schedule(struct ip_vs_service *svc) { struct ip_vs_dest *dest, *least; int loh, doh; /* * We use the following formula to estimate the load: * (dest overhead) / dest->weight * * Remember -- no floats in kernel mode!!! * The comparison of h1*w2 > h2*w1 is equivalent to that of * h1/w1 > h2/w2 * if every weight is larger than zero. * * The server with weight=0 is quiesced and will not receive any * new connection. */ 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) { least = dest; loh = ip_vs_dest_conn_overhead(least); goto nextstage; } } return NULL; /* * Find the destination with the least load. */ nextstage: list_for_each_entry_continue_rcu(dest, &svc->destinations, n_list) { if (dest->flags & IP_VS_DEST_F_OVERLOAD) continue; doh = ip_vs_dest_conn_overhead(dest); if ((__s64)loh * atomic_read(&dest->weight) > (__s64)doh * atomic_read(&least->weight)) { least = dest; loh = doh; } } IP_VS_DBG_BUF(6, "LBLC: server %s:%d " "activeconns %d refcnt %d weight %d overhead %d\n", IP_VS_DBG_ADDR(least->af, &least->addr), ntohs(least->port), atomic_read(&least->activeconns), refcount_read(&least->refcnt), atomic_read(&least->weight), loh); return least; } /* * If this destination server is overloaded and there is a less loaded * server, then return true. */ static inline int 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_rcu(d, &svc->destinations, n_list) { if (atomic_read(&d->activeconns)*2 < atomic_read(&d->weight)) { return 1; } } } return 0; } /* * Locality-Based (weighted) Least-Connection scheduling */ static struct ip_vs_dest * ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, struct ip_vs_iphdr *iph) { struct ip_vs_lblc_table *tbl = svc->sched_data; struct ip_vs_dest *dest = NULL; struct ip_vs_lblc_entry *en; IP_VS_DBG(6, "%s(): Scheduling...\n", __func__); /* First look in our cache */ en = ip_vs_lblc_get(svc->af, tbl, &iph->daddr); if (en) { /* We only hold a read lock, but this is atomic */ en->lastuse = jiffies; /* * If the destination is not available, i.e. it's in the trash, * we must ignore it, as it may be removed from under our feet, * if someone drops our reference count. Our caller only makes * sure that destinations, that are not in the trash, are not * moved to the trash, while we are scheduling. But anyone can * free up entries from the trash at any time. */ dest = 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); if (!dest) { ip_vs_scheduler_err(svc, "no destination available"); return NULL; } /* If we fail to create a cache entry, we'll just use the valid dest */ spin_lock_bh(&svc->sched_lock); if (!tbl->dead) ip_vs_lblc_new(tbl, &iph->daddr, svc->af, dest); spin_unlock_bh(&svc->sched_lock); out: IP_VS_DBG_BUF(6, "LBLC: destination IP address %s --> server %s:%d\n", IP_VS_DBG_ADDR(svc->af, &iph->daddr), IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port)); return dest; } /* * IPVS LBLC Scheduler structure */ static struct ip_vs_scheduler ip_vs_lblc_scheduler = { .name = "lblc", .refcnt = ATOMIC_INIT(0), .module = THIS_MODULE, .n_list = LIST_HEAD_INIT(ip_vs_lblc_scheduler.n_list), .init_service = ip_vs_lblc_init_svc, .done_service = ip_vs_lblc_done_svc, .schedule = ip_vs_lblc_schedule, }; /* * per netns init. */ #ifdef CONFIG_SYSCTL static int __net_init __ip_vs_lblc_init(struct net *net) { struct netns_ipvs *ipvs = net_ipvs(net); size_t vars_table_size = ARRAY_SIZE(vs_vars_table); if (!ipvs) return -ENOENT; if (!net_eq(net, &init_net)) { ipvs->lblc_ctl_table = kmemdup(vs_vars_table, sizeof(vs_vars_table), GFP_KERNEL); if (ipvs->lblc_ctl_table == NULL) return -ENOMEM; /* Don't export sysctls to unprivileged users */ if (net->user_ns != &init_user_ns) { ipvs->lblc_ctl_table[0].procname = NULL; vars_table_size = 0; } } else ipvs->lblc_ctl_table = vs_vars_table; ipvs->sysctl_lblc_expiration = DEFAULT_EXPIRATION; ipvs->lblc_ctl_table[0].data = &ipvs->sysctl_lblc_expiration; ipvs->lblc_ctl_header = register_net_sysctl_sz(net, "net/ipv4/vs", ipvs->lblc_ctl_table, vars_table_size); if (!ipvs->lblc_ctl_header) { if (!net_eq(net, &init_net)) kfree(ipvs->lblc_ctl_table); return -ENOMEM; } return 0; } static void __net_exit __ip_vs_lblc_exit(struct net *net) { struct netns_ipvs *ipvs = net_ipvs(net); unregister_net_sysctl_table(ipvs->lblc_ctl_header); if (!net_eq(net, &init_net)) kfree(ipvs->lblc_ctl_table); } #else static int __net_init __ip_vs_lblc_init(struct net *net) { return 0; } static void __net_exit __ip_vs_lblc_exit(struct net *net) { } #endif static struct pernet_operations ip_vs_lblc_ops = { .init = __ip_vs_lblc_init, .exit = __ip_vs_lblc_exit, }; static int __init ip_vs_lblc_init(void) { int ret; ret = register_pernet_subsys(&ip_vs_lblc_ops); if (ret) return ret; ret = register_ip_vs_scheduler(&ip_vs_lblc_scheduler); if (ret) unregister_pernet_subsys(&ip_vs_lblc_ops); return ret; } static void __exit ip_vs_lblc_cleanup(void) { unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler); unregister_pernet_subsys(&ip_vs_lblc_ops); rcu_barrier(); } module_init(ip_vs_lblc_init); module_exit(ip_vs_lblc_cleanup); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ipvs locality-based least-connection scheduler");