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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* flow.c: Generic flow cache.
2 *
3 * Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
4 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
5 */
6
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/list.h>
10#include <linux/jhash.h>
11#include <linux/interrupt.h>
12#include <linux/mm.h>
13#include <linux/random.h>
14#include <linux/init.h>
15#include <linux/slab.h>
16#include <linux/smp.h>
17#include <linux/completion.h>
18#include <linux/percpu.h>
19#include <linux/bitops.h>
20#include <linux/notifier.h>
21#include <linux/cpu.h>
22#include <linux/cpumask.h>
Arjan van de Ven4a3e2f72006-03-20 22:33:17 -080023#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <net/flow.h>
25#include <asm/atomic.h>
26#include <asm/semaphore.h>
Trent Jaegerdf718372005-12-13 23:12:27 -080027#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
29struct flow_cache_entry {
30 struct flow_cache_entry *next;
31 u16 family;
32 u8 dir;
33 struct flowi key;
34 u32 genid;
35 void *object;
36 atomic_t *object_ref;
37};
38
39atomic_t flow_cache_genid = ATOMIC_INIT(0);
40
41static u32 flow_hash_shift;
42#define flow_hash_size (1 << flow_hash_shift)
43static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
44
45#define flow_table(cpu) (per_cpu(flow_tables, cpu))
46
Eric Dumazetba899662005-08-26 12:05:31 -070047static kmem_cache_t *flow_cachep __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
49static int flow_lwm, flow_hwm;
50
51struct flow_percpu_info {
52 int hash_rnd_recalc;
53 u32 hash_rnd;
54 int count;
55} ____cacheline_aligned;
56static DEFINE_PER_CPU(struct flow_percpu_info, flow_hash_info) = { 0 };
57
58#define flow_hash_rnd_recalc(cpu) \
59 (per_cpu(flow_hash_info, cpu).hash_rnd_recalc)
60#define flow_hash_rnd(cpu) \
61 (per_cpu(flow_hash_info, cpu).hash_rnd)
62#define flow_count(cpu) \
63 (per_cpu(flow_hash_info, cpu).count)
64
65static struct timer_list flow_hash_rnd_timer;
66
67#define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
68
69struct flow_flush_info {
70 atomic_t cpuleft;
71 struct completion completion;
72};
73static DEFINE_PER_CPU(struct tasklet_struct, flow_flush_tasklets) = { NULL };
74
75#define flow_flush_tasklet(cpu) (&per_cpu(flow_flush_tasklets, cpu))
76
77static void flow_cache_new_hashrnd(unsigned long arg)
78{
79 int i;
80
KAMEZAWA Hiroyuki6f912042006-04-10 22:52:50 -070081 for_each_possible_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 flow_hash_rnd_recalc(i) = 1;
83
84 flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
85 add_timer(&flow_hash_rnd_timer);
86}
87
88static void __flow_cache_shrink(int cpu, int shrink_to)
89{
90 struct flow_cache_entry *fle, **flp;
91 int i;
92
93 for (i = 0; i < flow_hash_size; i++) {
94 int k = 0;
95
96 flp = &flow_table(cpu)[i];
97 while ((fle = *flp) != NULL && k < shrink_to) {
98 k++;
99 flp = &fle->next;
100 }
101 while ((fle = *flp) != NULL) {
102 *flp = fle->next;
103 if (fle->object)
104 atomic_dec(fle->object_ref);
105 kmem_cache_free(flow_cachep, fle);
106 flow_count(cpu)--;
107 }
108 }
109}
110
111static void flow_cache_shrink(int cpu)
112{
113 int shrink_to = flow_lwm / flow_hash_size;
114
115 __flow_cache_shrink(cpu, shrink_to);
116}
117
118static void flow_new_hash_rnd(int cpu)
119{
120 get_random_bytes(&flow_hash_rnd(cpu), sizeof(u32));
121 flow_hash_rnd_recalc(cpu) = 0;
122
123 __flow_cache_shrink(cpu, 0);
124}
125
126static u32 flow_hash_code(struct flowi *key, int cpu)
127{
128 u32 *k = (u32 *) key;
129
130 return (jhash2(k, (sizeof(*key) / sizeof(u32)), flow_hash_rnd(cpu)) &
131 (flow_hash_size - 1));
132}
133
134#if (BITS_PER_LONG == 64)
135typedef u64 flow_compare_t;
136#else
137typedef u32 flow_compare_t;
138#endif
139
140extern void flowi_is_missized(void);
141
142/* I hear what you're saying, use memcmp. But memcmp cannot make
143 * important assumptions that we can here, such as alignment and
144 * constant size.
145 */
146static int flow_key_compare(struct flowi *key1, struct flowi *key2)
147{
148 flow_compare_t *k1, *k1_lim, *k2;
149 const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
150
151 if (sizeof(struct flowi) % sizeof(flow_compare_t))
152 flowi_is_missized();
153
154 k1 = (flow_compare_t *) key1;
155 k1_lim = k1 + n_elem;
156
157 k2 = (flow_compare_t *) key2;
158
159 do {
160 if (*k1++ != *k2++)
161 return 1;
162 } while (k1 < k1_lim);
163
164 return 0;
165}
166
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700167void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 flow_resolve_t resolver)
169{
170 struct flow_cache_entry *fle, **head;
171 unsigned int hash;
172 int cpu;
173
174 local_bh_disable();
175 cpu = smp_processor_id();
176
177 fle = NULL;
178 /* Packet really early in init? Making flow_cache_init a
179 * pre-smp initcall would solve this. --RR */
180 if (!flow_table(cpu))
181 goto nocache;
182
183 if (flow_hash_rnd_recalc(cpu))
184 flow_new_hash_rnd(cpu);
185 hash = flow_hash_code(key, cpu);
186
187 head = &flow_table(cpu)[hash];
188 for (fle = *head; fle; fle = fle->next) {
189 if (fle->family == family &&
190 fle->dir == dir &&
191 flow_key_compare(key, &fle->key) == 0) {
192 if (fle->genid == atomic_read(&flow_cache_genid)) {
193 void *ret = fle->object;
194
195 if (ret)
196 atomic_inc(fle->object_ref);
197 local_bh_enable();
198
199 return ret;
200 }
201 break;
202 }
203 }
204
205 if (!fle) {
206 if (flow_count(cpu) > flow_hwm)
207 flow_cache_shrink(cpu);
208
209 fle = kmem_cache_alloc(flow_cachep, SLAB_ATOMIC);
210 if (fle) {
211 fle->next = *head;
212 *head = fle;
213 fle->family = family;
214 fle->dir = dir;
215 memcpy(&fle->key, key, sizeof(*key));
216 fle->object = NULL;
217 flow_count(cpu)++;
218 }
219 }
220
221nocache:
222 {
223 void *obj;
224 atomic_t *obj_ref;
225
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700226 resolver(key, family, dir, &obj, &obj_ref);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
228 if (fle) {
229 fle->genid = atomic_read(&flow_cache_genid);
230
231 if (fle->object)
232 atomic_dec(fle->object_ref);
233
234 fle->object = obj;
235 fle->object_ref = obj_ref;
236 if (obj)
237 atomic_inc(fle->object_ref);
238 }
239 local_bh_enable();
240
241 return obj;
242 }
243}
244
245static void flow_cache_flush_tasklet(unsigned long data)
246{
247 struct flow_flush_info *info = (void *)data;
248 int i;
249 int cpu;
250
251 cpu = smp_processor_id();
252 for (i = 0; i < flow_hash_size; i++) {
253 struct flow_cache_entry *fle;
254
255 fle = flow_table(cpu)[i];
256 for (; fle; fle = fle->next) {
257 unsigned genid = atomic_read(&flow_cache_genid);
258
259 if (!fle->object || fle->genid == genid)
260 continue;
261
262 fle->object = NULL;
263 atomic_dec(fle->object_ref);
264 }
265 }
266
267 if (atomic_dec_and_test(&info->cpuleft))
268 complete(&info->completion);
269}
270
271static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
272static void flow_cache_flush_per_cpu(void *data)
273{
274 struct flow_flush_info *info = data;
275 int cpu;
276 struct tasklet_struct *tasklet;
277
278 cpu = smp_processor_id();
279
280 tasklet = flow_flush_tasklet(cpu);
281 tasklet->data = (unsigned long)info;
282 tasklet_schedule(tasklet);
283}
284
285void flow_cache_flush(void)
286{
287 struct flow_flush_info info;
Arjan van de Ven4a3e2f72006-03-20 22:33:17 -0800288 static DEFINE_MUTEX(flow_flush_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289
290 /* Don't want cpus going down or up during this. */
291 lock_cpu_hotplug();
Arjan van de Ven4a3e2f72006-03-20 22:33:17 -0800292 mutex_lock(&flow_flush_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 atomic_set(&info.cpuleft, num_online_cpus());
294 init_completion(&info.completion);
295
296 local_bh_disable();
297 smp_call_function(flow_cache_flush_per_cpu, &info, 1, 0);
298 flow_cache_flush_tasklet((unsigned long)&info);
299 local_bh_enable();
300
301 wait_for_completion(&info.completion);
Arjan van de Ven4a3e2f72006-03-20 22:33:17 -0800302 mutex_unlock(&flow_flush_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 unlock_cpu_hotplug();
304}
305
306static void __devinit flow_cache_cpu_prepare(int cpu)
307{
308 struct tasklet_struct *tasklet;
309 unsigned long order;
310
311 for (order = 0;
312 (PAGE_SIZE << order) <
313 (sizeof(struct flow_cache_entry *)*flow_hash_size);
314 order++)
315 /* NOTHING */;
316
317 flow_table(cpu) = (struct flow_cache_entry **)
Andrew Morton77d04bd2006-04-07 14:52:59 -0700318 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 if (!flow_table(cpu))
320 panic("NET: failed to allocate flow cache order %lu\n", order);
321
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 flow_hash_rnd_recalc(cpu) = 1;
323 flow_count(cpu) = 0;
324
325 tasklet = flow_flush_tasklet(cpu);
326 tasklet_init(tasklet, flow_cache_flush_tasklet, 0);
327}
328
329#ifdef CONFIG_HOTPLUG_CPU
330static int flow_cache_cpu(struct notifier_block *nfb,
331 unsigned long action,
332 void *hcpu)
333{
334 if (action == CPU_DEAD)
335 __flow_cache_shrink((unsigned long)hcpu, 0);
336 return NOTIFY_OK;
337}
338#endif /* CONFIG_HOTPLUG_CPU */
339
340static int __init flow_cache_init(void)
341{
342 int i;
343
344 flow_cachep = kmem_cache_create("flow_cache",
345 sizeof(struct flow_cache_entry),
Alexey Dobriyane5d679f332006-08-26 19:25:52 -0700346 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 flow_hash_shift = 10;
349 flow_lwm = 2 * flow_hash_size;
350 flow_hwm = 4 * flow_hash_size;
351
352 init_timer(&flow_hash_rnd_timer);
353 flow_hash_rnd_timer.function = flow_cache_new_hashrnd;
354 flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
355 add_timer(&flow_hash_rnd_timer);
356
KAMEZAWA Hiroyuki6f912042006-04-10 22:52:50 -0700357 for_each_possible_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 flow_cache_cpu_prepare(i);
359
360 hotcpu_notifier(flow_cache_cpu, 0);
361 return 0;
362}
363
364module_init(flow_cache_init);
365
366EXPORT_SYMBOL(flow_cache_genid);
367EXPORT_SYMBOL(flow_cache_lookup);