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TOMOYO Linux Cross Reference
Linux/net/core/dst_cache.c

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  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);
169 

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