net/core/dst_cache.c

   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
  21 struct 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
  31 static 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
  42 static 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
  62 fail:
  63         idst->refresh_ts = jiffies;
  64         return NULL;
  65 }
  66
  67 struct 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 }
  74 EXPORT_SYMBOL_GPL(dst_cache_get);
  75
  76 struct 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 }
  92 EXPORT_SYMBOL_GPL(dst_cache_get_ip4);
  93
  94 void 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 }
 106 EXPORT_SYMBOL_GPL(dst_cache_set_ip4);
 107
 108 #if IS_ENABLED(CONFIG_IPV6)
 109 void 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 }
 122 EXPORT_SYMBOL_GPL(dst_cache_set_ip6);
 123
 124 struct 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 }
 141 EXPORT_SYMBOL_GPL(dst_cache_get_ip6);
 142 #endif
 143
 144 int 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 }
 154 EXPORT_SYMBOL_GPL(dst_cache_init);
 155
 156 void 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 }
 168 EXPORT_SYMBOL_GPL(dst_cache_destroy);