// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS: Locality-Based Least-Connection scheduling module
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*
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* Authors: Wensong Zhang <wensong@gnuchina.org>
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*
|
* Changes:
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* Martin Hamilton : fixed the terrible locking bugs
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* *lock(tbl->lock) ==> *lock(&tbl->lock)
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* Wensong Zhang : fixed the uninitialized tbl->lock bug
|
* Wensong Zhang : added doing full expiration check to
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* collect stale entries of 24+ hours when
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* no partial expire check in a half hour
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* 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};
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* else
|
* n <- cachenode[dest_ip];
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* 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};
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*
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* return n;
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*
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* Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing
|
* me to write this module.
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*/
|
|
#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
|
|
#include <linux/ip.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/jiffies.h>
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#include <linux/hash.h>
|
|
/* for sysctl */
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#include <linux/fs.h>
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#include <linux/sysctl.h>
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#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
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#define CONFIG_IP_VS_LBLC_TAB_BITS 10
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#endif
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#define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS
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#define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS)
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#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;
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int af; /* address family */
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union nf_inet_addr addr; /* destination IP address */
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struct ip_vs_dest *dest; /* real server (cache) */
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unsigned long lastuse; /* last used time */
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struct rcu_head rcu_head;
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};
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|
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/*
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* IPVS lblc hash table
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*/
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struct ip_vs_lblc_table {
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struct rcu_head rcu_head;
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struct hlist_head bucket[IP_VS_LBLC_TAB_SIZE]; /* hash bucket */
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struct timer_list periodic_timer; /* collect stale entries */
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struct ip_vs_service *svc; /* pointer back to service */
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atomic_t entries; /* number of entries */
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int max_size; /* maximum size of entries */
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int rover; /* rover for expire check */
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int counter; /* counter for no expire */
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bool dead;
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};
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|
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/*
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* IPVS LBLC sysctl table
|
*/
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#ifdef CONFIG_SYSCTL
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static struct ctl_table vs_vars_table[] = {
|
{
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.procname = "lblc_expiration",
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.data = NULL,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec_jiffies,
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},
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{ }
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};
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#endif
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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);
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|
ip_vs_dest_put_and_free(en->dest);
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kfree(en);
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}
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static inline void ip_vs_lblc_del(struct ip_vs_lblc_entry *en)
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{
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hlist_del_rcu(&en->list);
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call_rcu(&en->rcu_head, ip_vs_lblc_rcu_free);
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}
|
|
/*
|
* Returns hash value for IPVS LBLC entry
|
*/
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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
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return hash_32(ntohl(addr_fold), IP_VS_LBLC_TAB_BITS);
|
}
|
|
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/*
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* Hash an entry in the ip_vs_lblc_table.
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* returns bool success.
|
*/
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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);
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}
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|
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/* Get ip_vs_lblc_entry associated with supplied parameters. */
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static inline struct ip_vs_lblc_entry *
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ip_vs_lblc_get(int af, struct ip_vs_lblc_table *tbl,
|
const union nf_inet_addr *addr)
|
{
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unsigned int hash = ip_vs_lblc_hashkey(af, addr);
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struct ip_vs_lblc_entry *en;
|
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hlist_for_each_entry_rcu(en, &tbl->bucket[hash], list)
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if (ip_vs_addr_equal(af, &en->addr, addr))
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return en;
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|
return NULL;
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}
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|
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/*
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* Create or update an ip_vs_lblc_entry, which is a mapping of a destination IP
|
* address to a server. Called under spin lock.
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*/
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static inline struct ip_vs_lblc_entry *
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ip_vs_lblc_new(struct ip_vs_lblc_table *tbl, const union nf_inet_addr *daddr,
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u16 af, struct ip_vs_dest *dest)
|
{
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struct ip_vs_lblc_entry *en;
|
|
en = ip_vs_lblc_get(af, tbl, daddr);
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if (en) {
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if (en->dest == dest)
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return en;
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ip_vs_lblc_del(en);
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}
|
en = kmalloc(sizeof(*en), GFP_ATOMIC);
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if (!en)
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return NULL;
|
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en->af = af;
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ip_vs_addr_copy(af, &en->addr, daddr);
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en->lastuse = jiffies;
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ip_vs_dest_hold(dest);
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en->dest = dest;
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ip_vs_lblc_hash(tbl, en);
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return en;
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}
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|
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/*
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* Flush all the entries of the specified table.
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*/
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static void ip_vs_lblc_flush(struct ip_vs_service *svc)
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{
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struct ip_vs_lblc_table *tbl = svc->sched_data;
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struct ip_vs_lblc_entry *en;
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struct hlist_node *next;
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int i;
|
|
spin_lock_bh(&svc->sched_lock);
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tbl->dead = true;
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for (i = 0; i < IP_VS_LBLC_TAB_SIZE; i++) {
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hlist_for_each_entry_safe(en, next, &tbl->bucket[i], list) {
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ip_vs_lblc_del(en);
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atomic_dec(&tbl->entries);
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}
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}
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spin_unlock_bh(&svc->sched_lock);
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}
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static int sysctl_lblc_expiration(struct ip_vs_service *svc)
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{
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#ifdef CONFIG_SYSCTL
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return svc->ipvs->sysctl_lblc_expiration;
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#else
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return DEFAULT_EXPIRATION;
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#endif
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}
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static inline void ip_vs_lblc_full_check(struct ip_vs_service *svc)
|
{
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struct ip_vs_lblc_table *tbl = svc->sched_data;
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struct ip_vs_lblc_entry *en;
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struct hlist_node *next;
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unsigned long now = jiffies;
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int i, j;
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for (i = 0, j = tbl->rover; i < IP_VS_LBLC_TAB_SIZE; i++) {
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j = (j + 1) & IP_VS_LBLC_TAB_MASK;
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spin_lock(&svc->sched_lock);
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hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
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if (time_before(now,
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en->lastuse +
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sysctl_lblc_expiration(svc)))
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continue;
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ip_vs_lblc_del(en);
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atomic_dec(&tbl->entries);
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}
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spin_unlock(&svc->sched_lock);
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}
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tbl->rover = j;
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}
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|
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/*
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* Periodical timer handler for IPVS lblc table
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* It is used to collect stale entries when the number of entries
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* exceeds the maximum size of the table.
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*
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* Fixme: we probably need more complicated algorithm to collect
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* entries that have not been used for a long time even
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* if the number of entries doesn't exceed the maximum size
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* of the table.
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* The full expiration check is for this purpose now.
|
*/
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static void ip_vs_lblc_check_expire(struct timer_list *t)
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{
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struct ip_vs_lblc_table *tbl = from_timer(tbl, t, periodic_timer);
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struct ip_vs_service *svc = tbl->svc;
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unsigned long now = jiffies;
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int goal;
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int i, j;
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struct ip_vs_lblc_entry *en;
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struct hlist_node *next;
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if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
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/* do full expiration check */
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ip_vs_lblc_full_check(svc);
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tbl->counter = 1;
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goto out;
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}
|
|
if (atomic_read(&tbl->entries) <= tbl->max_size) {
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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;
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for (i = 0, j = tbl->rover; i < IP_VS_LBLC_TAB_SIZE; i++) {
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j = (j + 1) & IP_VS_LBLC_TAB_MASK;
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|
spin_lock(&svc->sched_lock);
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hlist_for_each_entry_safe(en, next, &tbl->bucket[j], list) {
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if (time_before(now, en->lastuse + ENTRY_TIMEOUT))
|
continue;
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|
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");
|
