/net/netfilter/ipvs/ip_vs_lblc.c
http://github.com/mirrors/linux · C · 630 lines · 385 code · 107 blank · 138 comment · 42 complexity · 812e8f00956c22f1462cfd00e9c0e884 MD5 · raw file
- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * IPVS: Locality-Based Least-Connection scheduling module
- *
- * Authors: Wensong Zhang <wensong@gnuchina.org>
- *
- * 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<m.weight/2) then
- * n, cachenode[dest_ip] <- {weighted least-conn node};
- *
- * return n;
- *
- * Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing
- * me to write this module.
- */
- #define KMSG_COMPONENT "IPVS"
- #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
- #include <linux/ip.h>
- #include <linux/slab.h>
- #include <linux/module.h>
- #include <linux/kernel.h>
- #include <linux/skbuff.h>
- #include <linux/jiffies.h>
- #include <linux/hash.h>
- /* for sysctl */
- #include <linux/fs.h>
- #include <linux/sysctl.h>
- #include <net/ip_vs.h>
- /*
- * 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 */
- del_timer_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);
- 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;
- } 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(net, "net/ipv4/vs", ipvs->lblc_ctl_table);
- 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");