xref: /kernel/linux/linux-5.10/net/core/dst_cache.c (revision 8c2ecf20) 
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
17struct 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
27static void dst_cache_per_cpu_dst_set(struct dst_cache_pcpu *dst_cache,
28				      struct dst_entry *dst, u32 cookie)
29{
30	dst_release(dst_cache->dst);
31	if (dst)
32		dst_hold(dst);
33
34	dst_cache->cookie = cookie;
35	dst_cache->dst = dst;
36}
37
38static struct dst_entry *dst_cache_per_cpu_get(struct dst_cache *dst_cache,
39					       struct dst_cache_pcpu *idst)
40{
41	struct dst_entry *dst;
42
43	dst = idst->dst;
44	if (!dst)
45		goto fail;
46
47	/* the cache already hold a dst reference; it can't go away */
48	dst_hold(dst);
49
50	if (unlikely(!time_after(idst->refresh_ts, dst_cache->reset_ts) ||
51		     (dst->obsolete && !dst->ops->check(dst, idst->cookie)))) {
52		dst_cache_per_cpu_dst_set(idst, NULL, 0);
53		dst_release(dst);
54		goto fail;
55	}
56	return dst;
57
58fail:
59	idst->refresh_ts = jiffies;
60	return NULL;
61}
62
63struct dst_entry *dst_cache_get(struct dst_cache *dst_cache)
64{
65	if (!dst_cache->cache)
66		return NULL;
67
68	return dst_cache_per_cpu_get(dst_cache, this_cpu_ptr(dst_cache->cache));
69}
70EXPORT_SYMBOL_GPL(dst_cache_get);
71
72struct rtable *dst_cache_get_ip4(struct dst_cache *dst_cache, __be32 *saddr)
73{
74	struct dst_cache_pcpu *idst;
75	struct dst_entry *dst;
76
77	if (!dst_cache->cache)
78		return NULL;
79
80	idst = this_cpu_ptr(dst_cache->cache);
81	dst = dst_cache_per_cpu_get(dst_cache, idst);
82	if (!dst)
83		return NULL;
84
85	*saddr = idst->in_saddr.s_addr;
86	return container_of(dst, struct rtable, dst);
87}
88EXPORT_SYMBOL_GPL(dst_cache_get_ip4);
89
90void dst_cache_set_ip4(struct dst_cache *dst_cache, struct dst_entry *dst,
91		       __be32 saddr)
92{
93	struct dst_cache_pcpu *idst;
94
95	if (!dst_cache->cache)
96		return;
97
98	idst = this_cpu_ptr(dst_cache->cache);
99	dst_cache_per_cpu_dst_set(idst, dst, 0);
100	idst->in_saddr.s_addr = saddr;
101}
102EXPORT_SYMBOL_GPL(dst_cache_set_ip4);
103
104#if IS_ENABLED(CONFIG_IPV6)
105void dst_cache_set_ip6(struct dst_cache *dst_cache, struct dst_entry *dst,
106		       const struct in6_addr *saddr)
107{
108	struct dst_cache_pcpu *idst;
109
110	if (!dst_cache->cache)
111		return;
112
113	idst = this_cpu_ptr(dst_cache->cache);
114	dst_cache_per_cpu_dst_set(this_cpu_ptr(dst_cache->cache), dst,
115				  rt6_get_cookie((struct rt6_info *)dst));
116	idst->in6_saddr = *saddr;
117}
118EXPORT_SYMBOL_GPL(dst_cache_set_ip6);
119
120struct dst_entry *dst_cache_get_ip6(struct dst_cache *dst_cache,
121				    struct in6_addr *saddr)
122{
123	struct dst_cache_pcpu *idst;
124	struct dst_entry *dst;
125
126	if (!dst_cache->cache)
127		return NULL;
128
129	idst = this_cpu_ptr(dst_cache->cache);
130	dst = dst_cache_per_cpu_get(dst_cache, idst);
131	if (!dst)
132		return NULL;
133
134	*saddr = idst->in6_saddr;
135	return dst;
136}
137EXPORT_SYMBOL_GPL(dst_cache_get_ip6);
138#endif
139
140int dst_cache_init(struct dst_cache *dst_cache, gfp_t gfp)
141{
142	dst_cache->cache = alloc_percpu_gfp(struct dst_cache_pcpu,
143					    gfp | __GFP_ZERO);
144	if (!dst_cache->cache)
145		return -ENOMEM;
146
147	dst_cache_reset(dst_cache);
148	return 0;
149}
150EXPORT_SYMBOL_GPL(dst_cache_init);
151
152void dst_cache_destroy(struct dst_cache *dst_cache)
153{
154	int i;
155
156	if (!dst_cache->cache)
157		return;
158
159	for_each_possible_cpu(i)
160		dst_release(per_cpu_ptr(dst_cache->cache, i)->dst);
161
162	free_percpu(dst_cache->cache);
163}
164EXPORT_SYMBOL_GPL(dst_cache_destroy);
165
166void dst_cache_reset_now(struct dst_cache *dst_cache)
167{
168	int i;
169
170	if (!dst_cache->cache)
171		return;
172
173	dst_cache->reset_ts = jiffies;
174	for_each_possible_cpu(i) {
175		struct dst_cache_pcpu *idst = per_cpu_ptr(dst_cache->cache, i);
176		struct dst_entry *dst = idst->dst;
177
178		idst->cookie = 0;
179		idst->dst = NULL;
180		dst_release(dst);
181	}
182}
183EXPORT_SYMBOL_GPL(dst_cache_reset_now);
184