net/core/dst_cache.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/core/dst_cache.c - dst entry cache
   4  *
   5  * Copyright (c) 2016 Paolo Abeni <pabeni@redhat.com>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/percpu.h>
  10 #include <net/dst_cache.h>
  11 #include <net/route.h>
  12 #if IS_ENABLED(CONFIG_IPV6)
  13 #include <net/ip6_fib.h>
  14 #endif
  15 #include <uapi/linux/in.h>
  16
  17 struct dst_cache_pcpu {
  18         unsigned long refresh_ts;
  19         struct dst_entry *dst;
  20         u32 cookie;
  21         union {
  22                 struct in_addr in_saddr;
  23                 struct in6_addr in6_saddr;
  24         };
  25 };
  26
  27 static void dst_cache_per_cpu_dst_set(struct dst_cache_pcpu *dst_cache,
  28                                       struct dst_entry *dst, u32 cookie)
  29 {
  30         DEBUG_NET_WARN_ON_ONCE(!in_softirq());
  31         dst_release(dst_cache->dst);
  32         if (dst)
  33                 dst_hold(dst);
  34
  35         dst_cache->cookie = cookie;
  36         dst_cache->dst = dst;
  37 }
  38
  39 static struct dst_entry *dst_cache_per_cpu_get(struct dst_cache *dst_cache,
  40                                                struct dst_cache_pcpu *idst)
  41 {
  42         struct dst_entry *dst;
  43
  44         DEBUG_NET_WARN_ON_ONCE(!in_softirq());
  45         dst = idst->dst;
  46         if (!dst)
  47                 goto fail;
  48
  49         /* the cache already hold a dst reference; it can't go away */
  50         dst_hold(dst);
  51
  52         if (unlikely(!time_after(idst->refresh_ts,
  53                                  READ_ONCE(dst_cache->reset_ts)) ||
  54                      (dst->obsolete && !dst->ops->check(dst, idst->cookie)))) {
  55                 dst_cache_per_cpu_dst_set(idst, NULL, 0);
  56                 dst_release(dst);
  57                 goto fail;
  58         }
  59         return dst;
  60
  61 fail:
  62         idst->refresh_ts = jiffies;
  63         return NULL;
  64 }
  65
  66 struct dst_entry *dst_cache_get(struct dst_cache *dst_cache)
  67 {
  68         if (!dst_cache->cache)
  69                 return NULL;
  70
  71         return dst_cache_per_cpu_get(dst_cache, this_cpu_ptr(dst_cache->cache));
  72 }
  73 EXPORT_SYMBOL_GPL(dst_cache_get);
  74
  75 struct rtable *dst_cache_get_ip4(struct dst_cache *dst_cache, __be32 *saddr)
  76 {
  77         struct dst_cache_pcpu *idst;
  78         struct dst_entry *dst;
  79
  80         if (!dst_cache->cache)
  81                 return NULL;
  82
  83         idst = this_cpu_ptr(dst_cache->cache);
  84         dst = dst_cache_per_cpu_get(dst_cache, idst);
  85         if (!dst)
  86                 return NULL;
  87
  88         *saddr = idst->in_saddr.s_addr;
  89         return dst_rtable(dst);
  90 }
  91 EXPORT_SYMBOL_GPL(dst_cache_get_ip4);
  92
  93 void dst_cache_set_ip4(struct dst_cache *dst_cache, struct dst_entry *dst,
  94                        __be32 saddr)
  95 {
  96         struct dst_cache_pcpu *idst;
  97
  98         if (!dst_cache->cache)
  99                 return;
 100
 101         idst = this_cpu_ptr(dst_cache->cache);
 102         dst_cache_per_cpu_dst_set(idst, dst, 0);
 103         idst->in_saddr.s_addr = saddr;
 104 }
 105 EXPORT_SYMBOL_GPL(dst_cache_set_ip4);
 106
 107 #if IS_ENABLED(CONFIG_IPV6)
 108 void dst_cache_set_ip6(struct dst_cache *dst_cache, struct dst_entry *dst,
 109                        const struct in6_addr *saddr)
 110 {
 111         struct dst_cache_pcpu *idst;
 112
 113         if (!dst_cache->cache)
 114                 return;
 115
 116         idst = this_cpu_ptr(dst_cache->cache);
 117         dst_cache_per_cpu_dst_set(idst, dst,
 118                                   rt6_get_cookie(dst_rt6_info(dst)));
 119         idst->in6_saddr = *saddr;
 120 }
 121 EXPORT_SYMBOL_GPL(dst_cache_set_ip6);
 122
 123 struct dst_entry *dst_cache_get_ip6(struct dst_cache *dst_cache,
 124                                     struct in6_addr *saddr)
 125 {
 126         struct dst_cache_pcpu *idst;
 127         struct dst_entry *dst;
 128
 129         if (!dst_cache->cache)
 130                 return NULL;
 131
 132         idst = this_cpu_ptr(dst_cache->cache);
 133         dst = dst_cache_per_cpu_get(dst_cache, idst);
 134         if (!dst)
 135                 return NULL;
 136
 137         *saddr = idst->in6_saddr;
 138         return dst;
 139 }
 140 EXPORT_SYMBOL_GPL(dst_cache_get_ip6);
 141 #endif
 142
 143 int dst_cache_init(struct dst_cache *dst_cache, gfp_t gfp)
 144 {
 145         dst_cache->cache = alloc_percpu_gfp(struct dst_cache_pcpu,
 146                                             gfp | __GFP_ZERO);
 147         if (!dst_cache->cache)
 148                 return -ENOMEM;
 149
 150         dst_cache_reset(dst_cache);
 151         return 0;
 152 }
 153 EXPORT_SYMBOL_GPL(dst_cache_init);
 154
 155 void dst_cache_destroy(struct dst_cache *dst_cache)
 156 {
 157         int i;
 158
 159         if (!dst_cache->cache)
 160                 return;
 161
 162         for_each_possible_cpu(i)
 163                 dst_release(per_cpu_ptr(dst_cache->cache, i)->dst);
 164
 165         free_percpu(dst_cache->cache);
 166 }
 167 EXPORT_SYMBOL_GPL(dst_cache_destroy);
 168
 169 void dst_cache_reset_now(struct dst_cache *dst_cache)
 170 {
 171         int i;
 172
 173         if (!dst_cache->cache)
 174                 return;
 175
 176         dst_cache_reset(dst_cache);
 177         for_each_possible_cpu(i) {
 178                 struct dst_cache_pcpu *idst = per_cpu_ptr(dst_cache->cache, i);
 179                 struct dst_entry *dst = idst->dst;
 180
 181                 idst->cookie = 0;
 182                 idst->dst = NULL;
 183                 dst_release(dst);
 184         }
 185 }
 186 EXPORT_SYMBOL_GPL(dst_cache_reset_now);