![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
379 lines
9.2 KiB
C
379 lines
9.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPVS: Source Hashing scheduling module
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*
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* Authors: Wensong Zhang <wensong@gnuchina.org>
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*
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* Changes:
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*/
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/*
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* The sh algorithm is to select server by the hash key of source IP
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* address. The pseudo code is as follows:
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*
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* n <- servernode[src_ip];
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* if (n is dead) OR
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* (n is overloaded) or (n.weight <= 0) then
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* return NULL;
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*
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* return n;
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*
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* Notes that servernode is a 256-bucket hash table that maps the hash
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* index derived from packet source IP address to the current server
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* array. If the sh scheduler is used in cache cluster, it is good to
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* combine it with cache_bypass feature. When the statically assigned
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* server is dead or overloaded, the load balancer can bypass the cache
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* server and send requests to the original server directly.
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*
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* The weight destination attribute can be used to control the
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* distribution of connections to the destinations in servernode. The
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* greater the weight, the more connections the destination
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* will receive.
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*
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*/
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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#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 <net/ip_vs.h>
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#include <net/tcp.h>
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#include <linux/udp.h>
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#include <linux/sctp.h>
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/*
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* IPVS SH bucket
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*/
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struct ip_vs_sh_bucket {
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struct ip_vs_dest __rcu *dest; /* real server (cache) */
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};
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/*
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* for IPVS SH entry hash table
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*/
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#ifndef CONFIG_IP_VS_SH_TAB_BITS
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#define CONFIG_IP_VS_SH_TAB_BITS 8
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#endif
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#define IP_VS_SH_TAB_BITS CONFIG_IP_VS_SH_TAB_BITS
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#define IP_VS_SH_TAB_SIZE (1 << IP_VS_SH_TAB_BITS)
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#define IP_VS_SH_TAB_MASK (IP_VS_SH_TAB_SIZE - 1)
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struct ip_vs_sh_state {
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struct rcu_head rcu_head;
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struct ip_vs_sh_bucket buckets[IP_VS_SH_TAB_SIZE];
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};
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/* Helper function to determine if server is unavailable */
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static inline bool is_unavailable(struct ip_vs_dest *dest)
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{
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return atomic_read(&dest->weight) <= 0 ||
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dest->flags & IP_VS_DEST_F_OVERLOAD;
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}
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/*
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* Returns hash value for IPVS SH entry
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*/
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static inline unsigned int
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ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr,
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__be16 port, unsigned int offset)
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{
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__be32 addr_fold = addr->ip;
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#ifdef CONFIG_IP_VS_IPV6
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if (af == AF_INET6)
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addr_fold = addr->ip6[0]^addr->ip6[1]^
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addr->ip6[2]^addr->ip6[3];
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#endif
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return (offset + hash_32(ntohs(port) + ntohl(addr_fold),
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IP_VS_SH_TAB_BITS)) &
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IP_VS_SH_TAB_MASK;
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}
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/*
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* Get ip_vs_dest associated with supplied parameters.
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*/
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static inline struct ip_vs_dest *
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ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s,
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const union nf_inet_addr *addr, __be16 port)
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{
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unsigned int hash = ip_vs_sh_hashkey(svc->af, addr, port, 0);
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struct ip_vs_dest *dest = rcu_dereference(s->buckets[hash].dest);
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return (!dest || is_unavailable(dest)) ? NULL : dest;
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}
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/* As ip_vs_sh_get, but with fallback if selected server is unavailable
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*
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* The fallback strategy loops around the table starting from a "random"
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* point (in fact, it is chosen to be the original hash value to make the
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* algorithm deterministic) to find a new server.
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*/
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static inline struct ip_vs_dest *
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ip_vs_sh_get_fallback(struct ip_vs_service *svc, struct ip_vs_sh_state *s,
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const union nf_inet_addr *addr, __be16 port)
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{
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unsigned int offset, roffset;
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unsigned int hash, ihash;
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struct ip_vs_dest *dest;
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/* first try the dest it's supposed to go to */
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ihash = ip_vs_sh_hashkey(svc->af, addr, port, 0);
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dest = rcu_dereference(s->buckets[ihash].dest);
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if (!dest)
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return NULL;
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if (!is_unavailable(dest))
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return dest;
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IP_VS_DBG_BUF(6, "SH: selected unavailable server %s:%d, reselecting",
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IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port));
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/* if the original dest is unavailable, loop around the table
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* starting from ihash to find a new dest
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*/
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for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) {
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roffset = (offset + ihash) % IP_VS_SH_TAB_SIZE;
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hash = ip_vs_sh_hashkey(svc->af, addr, port, roffset);
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dest = rcu_dereference(s->buckets[hash].dest);
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if (!dest)
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break;
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if (!is_unavailable(dest))
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return dest;
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IP_VS_DBG_BUF(6, "SH: selected unavailable "
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"server %s:%d (offset %d), reselecting",
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IP_VS_DBG_ADDR(dest->af, &dest->addr),
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ntohs(dest->port), roffset);
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}
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return NULL;
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}
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/*
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* Assign all the hash buckets of the specified table with the service.
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*/
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static int
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ip_vs_sh_reassign(struct ip_vs_sh_state *s, struct ip_vs_service *svc)
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{
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int i;
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struct ip_vs_sh_bucket *b;
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struct list_head *p;
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struct ip_vs_dest *dest;
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int d_count;
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bool empty;
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b = &s->buckets[0];
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p = &svc->destinations;
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empty = list_empty(p);
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d_count = 0;
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for (i=0; i<IP_VS_SH_TAB_SIZE; i++) {
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dest = rcu_dereference_protected(b->dest, 1);
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if (dest)
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ip_vs_dest_put(dest);
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if (empty)
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RCU_INIT_POINTER(b->dest, NULL);
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else {
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if (p == &svc->destinations)
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p = p->next;
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dest = list_entry(p, struct ip_vs_dest, n_list);
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ip_vs_dest_hold(dest);
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RCU_INIT_POINTER(b->dest, dest);
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IP_VS_DBG_BUF(6, "assigned i: %d dest: %s weight: %d\n",
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i, IP_VS_DBG_ADDR(dest->af, &dest->addr),
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atomic_read(&dest->weight));
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/* Don't move to next dest until filling weight */
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if (++d_count >= atomic_read(&dest->weight)) {
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p = p->next;
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d_count = 0;
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}
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}
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b++;
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}
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return 0;
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}
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/*
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* Flush all the hash buckets of the specified table.
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*/
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static void ip_vs_sh_flush(struct ip_vs_sh_state *s)
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{
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int i;
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struct ip_vs_sh_bucket *b;
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struct ip_vs_dest *dest;
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b = &s->buckets[0];
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for (i=0; i<IP_VS_SH_TAB_SIZE; i++) {
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dest = rcu_dereference_protected(b->dest, 1);
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if (dest) {
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ip_vs_dest_put(dest);
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RCU_INIT_POINTER(b->dest, NULL);
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}
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b++;
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}
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}
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static int ip_vs_sh_init_svc(struct ip_vs_service *svc)
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{
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struct ip_vs_sh_state *s;
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/* allocate the SH table for this service */
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s = kzalloc(sizeof(struct ip_vs_sh_state), GFP_KERNEL);
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if (s == NULL)
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return -ENOMEM;
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svc->sched_data = s;
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IP_VS_DBG(6, "SH hash table (memory=%zdbytes) allocated for "
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"current service\n",
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sizeof(struct ip_vs_sh_bucket)*IP_VS_SH_TAB_SIZE);
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/* assign the hash buckets with current dests */
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ip_vs_sh_reassign(s, svc);
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return 0;
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}
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static void ip_vs_sh_done_svc(struct ip_vs_service *svc)
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{
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struct ip_vs_sh_state *s = svc->sched_data;
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/* got to clean up hash buckets here */
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ip_vs_sh_flush(s);
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/* release the table itself */
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kfree_rcu(s, rcu_head);
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IP_VS_DBG(6, "SH hash table (memory=%zdbytes) released\n",
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sizeof(struct ip_vs_sh_bucket)*IP_VS_SH_TAB_SIZE);
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}
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static int ip_vs_sh_dest_changed(struct ip_vs_service *svc,
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struct ip_vs_dest *dest)
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{
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struct ip_vs_sh_state *s = svc->sched_data;
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/* assign the hash buckets with the updated service */
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ip_vs_sh_reassign(s, svc);
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return 0;
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}
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/* Helper function to get port number */
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static inline __be16
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ip_vs_sh_get_port(const struct sk_buff *skb, struct ip_vs_iphdr *iph)
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{
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__be16 _ports[2], *ports;
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/* At this point we know that we have a valid packet of some kind.
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* Because ICMP packets are only guaranteed to have the first 8
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* bytes, let's just grab the ports. Fortunately they're in the
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* same position for all three of the protocols we care about.
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*/
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switch (iph->protocol) {
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case IPPROTO_TCP:
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case IPPROTO_UDP:
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case IPPROTO_SCTP:
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ports = skb_header_pointer(skb, iph->len, sizeof(_ports),
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&_ports);
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if (unlikely(!ports))
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return 0;
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if (likely(!ip_vs_iph_inverse(iph)))
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return ports[0];
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else
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return ports[1];
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default:
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return 0;
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}
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}
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/*
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* Source Hashing scheduling
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*/
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static struct ip_vs_dest *
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ip_vs_sh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
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struct ip_vs_iphdr *iph)
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{
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struct ip_vs_dest *dest;
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struct ip_vs_sh_state *s;
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__be16 port = 0;
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const union nf_inet_addr *hash_addr;
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hash_addr = ip_vs_iph_inverse(iph) ? &iph->daddr : &iph->saddr;
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IP_VS_DBG(6, "ip_vs_sh_schedule(): Scheduling...\n");
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if (svc->flags & IP_VS_SVC_F_SCHED_SH_PORT)
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port = ip_vs_sh_get_port(skb, iph);
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s = (struct ip_vs_sh_state *) svc->sched_data;
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if (svc->flags & IP_VS_SVC_F_SCHED_SH_FALLBACK)
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dest = ip_vs_sh_get_fallback(svc, s, hash_addr, port);
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else
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dest = ip_vs_sh_get(svc, s, hash_addr, port);
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if (!dest) {
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ip_vs_scheduler_err(svc, "no destination available");
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return NULL;
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}
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IP_VS_DBG_BUF(6, "SH: source IP address %s --> server %s:%d\n",
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IP_VS_DBG_ADDR(svc->af, hash_addr),
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IP_VS_DBG_ADDR(dest->af, &dest->addr),
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ntohs(dest->port));
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return dest;
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}
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/*
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* IPVS SH Scheduler structure
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*/
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static struct ip_vs_scheduler ip_vs_sh_scheduler =
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{
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.name = "sh",
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.refcnt = ATOMIC_INIT(0),
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.module = THIS_MODULE,
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.n_list = LIST_HEAD_INIT(ip_vs_sh_scheduler.n_list),
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.init_service = ip_vs_sh_init_svc,
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.done_service = ip_vs_sh_done_svc,
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.add_dest = ip_vs_sh_dest_changed,
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.del_dest = ip_vs_sh_dest_changed,
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.upd_dest = ip_vs_sh_dest_changed,
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.schedule = ip_vs_sh_schedule,
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};
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static int __init ip_vs_sh_init(void)
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{
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return register_ip_vs_scheduler(&ip_vs_sh_scheduler);
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}
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static void __exit ip_vs_sh_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_sh_scheduler);
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synchronize_rcu();
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}
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module_init(ip_vs_sh_init);
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module_exit(ip_vs_sh_cleanup);
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MODULE_LICENSE("GPL");
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