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 *saddr)
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 = *saddr;
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);