LXR linux/net/core/dst

   1/*
   2 * net/core/dst_cache.c - dst entry cache
   3 *
   4 * Copyright (c) 2016 Paolo Abeni <pabeni@redhat.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 */
  11
  12#include <linux/kernel.h>
  13#include <linux/percpu.h>
  14#include <net/dst_cache.h>
  15#include <net/route.h>
  16#if IS_ENABLED(CONFIG_IPV6)
  17#include <net/ip6_fib.h>
  18#endif
  19#include <uapi/linux/in.h>
  20
  21struct dst_cache_pcpu {
  22        unsigned long refresh_ts;
  23        struct dst_entry *dst;
  24        u32 cookie;
  25        union {
  26                struct in_addr in_saddr;
  27                struct in6_addr in6_saddr;
  28        };
  29};
  30
  31static void dst_cache_per_cpu_dst_set(struct dst_cache_pcpu *dst_cache,
  32                                      struct dst_entry *dst, u32 cookie)
  33{
  34        dst_release(dst_cache->dst);
  35        if (dst)
  36                dst_hold(dst);
  37
  38        dst_cache->cookie = cookie;
  39        dst_cache->dst = dst;
  40}
  41
  42static struct dst_entry *dst_cache_per_cpu_get(struct dst_cache *dst_cache,
  43                                               struct dst_cache_pcpu *idst)
  44{
  45        struct dst_entry *dst;
  46
  47        dst = idst->dst;
  48        if (!dst)
  49                goto fail;
  50
  51        /* the cache already hold a dst reference; it can't go away */
  52        dst_hold(dst);
  53
  54        if (unlikely(!time_after(idst->refresh_ts, dst_cache->reset_ts) ||
  55                     (dst->obsolete && !dst->ops->check(dst, idst->cookie)))) {
  56                dst_cache_per_cpu_dst_set(idst, NULL, 0);
  57                dst_release(dst);
  58                goto fail;
  59        }
  60        return dst;
  61
  62fail:
  63        idst->refresh_ts = jiffies;
  64        return NULL;
  65}
  66
  67struct dst_entry *dst_cache_get(struct dst_cache *dst_cache)
  68{
  69        if (!dst_cache->cache)
  70                return NULL;
  71
  72        return dst_cache_per_cpu_get(dst_cache, this_cpu_ptr(dst_cache->cache));
  73}
  74EXPORT_SYMBOL_GPL(dst_cache_get);
  75
  76struct rtable *dst_cache_get_ip4(struct dst_cache *dst_cache, __be32 *saddr)
  77{
  78        struct dst_cache_pcpu *idst;
  79        struct dst_entry *dst;
  80
  81        if (!dst_cache->cache)
  82                return NULL;
  83
  84        idst = this_cpu_ptr(dst_cache->cache);
  85        dst = dst_cache_per_cpu_get(dst_cache, idst);
  86        if (!dst)
  87                return NULL;
  88
  89        *saddr = idst->in_saddr.s_addr;
  90        return container_of(dst, struct rtable, dst);
  91}
  92EXPORT_SYMBOL_GPL(dst_cache_get_ip4);
  93
  94void dst_cache_set_ip4(struct dst_cache *dst_cache, struct dst_entry *dst,
  95                       __be32 saddr)
  96{
  97        struct dst_cache_pcpu *idst;
  98
  99        if (!dst_cache->cache)
 100                return;
 101
 102        idst = this_cpu_ptr(dst_cache->cache);
 103        dst_cache_per_cpu_dst_set(idst, dst, 0);
 104        idst->in_saddr.s_addr = saddr;
 105}
 106EXPORT_SYMBOL_GPL(dst_cache_set_ip4);
 107
 108#if IS_ENABLED(CONFIG_IPV6)
 109void dst_cache_set_ip6(struct dst_cache *dst_cache, struct dst_entry *dst,
 110                       const struct in6_addr *addr)
 111{
 112        struct dst_cache_pcpu *idst;
 113
 114        if (!dst_cache->cache)
 115                return;
 116
 117        idst = this_cpu_ptr(dst_cache->cache);
 118        dst_cache_per_cpu_dst_set(this_cpu_ptr(dst_cache->cache), dst,
 119                                  rt6_get_cookie((struct rt6_info *)dst));
 120        idst->in6_saddr = *addr;
 121}
 122EXPORT_SYMBOL_GPL(dst_cache_set_ip6);
 123
 124struct dst_entry *dst_cache_get_ip6(struct dst_cache *dst_cache,
 125                                    struct in6_addr *saddr)
 126{
 127        struct dst_cache_pcpu *idst;
 128        struct dst_entry *dst;
 129
 130        if (!dst_cache->cache)
 131                return NULL;
 132
 133        idst = this_cpu_ptr(dst_cache->cache);
 134        dst = dst_cache_per_cpu_get(dst_cache, idst);
 135        if (!dst)
 136                return NULL;
 137
 138        *saddr = idst->in6_saddr;
 139        return dst;
 140}
 141EXPORT_SYMBOL_GPL(dst_cache_get_ip6);
 142#endif
 143
 144int dst_cache_init(struct dst_cache *dst_cache, gfp_t gfp)
 145{
 146        dst_cache->cache = alloc_percpu_gfp(struct dst_cache_pcpu,
 147                                            gfp | __GFP_ZERO);
 148        if (!dst_cache->cache)
 149                return -ENOMEM;
 150
 151        dst_cache_reset(dst_cache);
 152        return 0;
 153}
 154EXPORT_SYMBOL_GPL(dst_cache_init);
 155
 156void dst_cache_destroy(struct dst_cache *dst_cache)
 157{
 158        int i;
 159
 160        if (!dst_cache->cache)
 161                return;
 162
 163        for_each_possible_cpu(i)
 164                dst_release(per_cpu_ptr(dst_cache->cache, i)->dst);
 165
 166        free_percpu(dst_cache->cache);
 167}
 168EXPORT_SYMBOL_GPL(dst_cache_destroy);
 169