1 /* 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>
23 #include <linux/mutex.h>
24 #include <net/flow.h>
25 #include <asm/atomic.h>
26 #include <asm/semaphore.h>
27 #include <linux/security.h>
28
29 struct flow_cache_entry {
30 struct flow_cache_entry *next;
31 u16 family;
32 u8 dir;
33 u32 genid;
34 struct flowi key;
35 void *object;
36 atomic_t *object_ref;
37 };
38
39 atomic_t flow_cache_genid = ATOMIC_INIT(0);
40
41 static u32 flow_hash_shift;
42 #define flow_hash_size (1 << flow_hash_shift)
43 static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
44
45 #define flow_table(cpu) (per_cpu(flow_tables, cpu))
46
47 static struct kmem_cache *flow_cachep __read_mostly;
48
49 static int flow_lwm, flow_hwm;
50
51 struct flow_percpu_info {
52 int hash_rnd_recalc;
53 u32 hash_rnd;
54 int count;
55 };
56 static 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
65 static struct timer_list flow_hash_rnd_timer;
66
67 #define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
68
69 struct flow_flush_info {
70 atomic_t cpuleft;
71 struct completion completion;
72 };
73 static DEFINE_PER_CPU(struct tasklet_struct, flow_flush_tasklets) = { NULL };
74
75 #define flow_flush_tasklet(cpu) (&per_cpu(flow_flush_tasklets, cpu))
76
77 static void flow_cache_new_hashrnd(unsigned long arg)
78 {
79 int i;
80
81 for_each_possible_cpu(i)
82 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
88 static void flow_entry_kill(int cpu, struct flow_cache_entry *fle)
89 {
90 if (fle->object)
91 atomic_dec(fle->object_ref);
92 kmem_cache_free(flow_cachep, fle);
93 flow_count(cpu)--;
94 }
95
96 static void __flow_cache_shrink(int cpu, int shrink_to)
97 {
98 struct flow_cache_entry *fle, **flp;
99 int i;
100
101 for (i = 0; i < flow_hash_size; i++) {
102 int k = 0;
103
104 flp = &flow_table(cpu)[i];
105 while ((fle = *flp) != NULL && k < shrink_to) {
106 k++;
107 flp = &fle->next;
108 }
109 while ((fle = *flp) != NULL) {
110 *flp = fle->next;
111 flow_entry_kill(cpu, fle);
112 }
113 }
114 }
115
116 static void flow_cache_shrink(int cpu)
117 {
118 int shrink_to = flow_lwm / flow_hash_size;
119
120 __flow_cache_shrink(cpu, shrink_to);
121 }
122
123 static void flow_new_hash_rnd(int cpu)
124 {
125 get_random_bytes(&flow_hash_rnd(cpu), sizeof(u32));
126 flow_hash_rnd_recalc(cpu) = 0;
127
128 __flow_cache_shrink(cpu, 0);
129 }
130
131 static u32 flow_hash_code(struct flowi *key, int cpu)
132 {
133 u32 *k = (u32 *) key;
134
135 return (jhash2(k, (sizeof(*key) / sizeof(u32)), flow_hash_rnd(cpu)) &
136 (flow_hash_size - 1));
137 }
138
139 #if (BITS_PER_LONG == 64)
140 typedef u64 flow_compare_t;
141 #else
142 typedef u32 flow_compare_t;
143 #endif
144
145 /* I hear what you're saying, use memcmp. But memcmp cannot make
146 * important assumptions that we can here, such as alignment and
147 * constant size.
148 */
149 static int flow_key_compare(struct flowi *key1, struct flowi *key2)
150 {
151 flow_compare_t *k1, *k1_lim, *k2;
152 const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
153
154 BUILD_BUG_ON(sizeof(struct flowi) % sizeof(flow_compare_t));
155
156 k1 = (flow_compare_t *) key1;
157 k1_lim = k1 + n_elem;
158
159 k2 = (flow_compare_t *) key2;
160
161 do {
162 if (*k1++ != *k2++)
163 return 1;
164 } while (k1 < k1_lim);
165
166 return 0;
167 }
168
169 void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
170 flow_resolve_t resolver)
171 {
172 struct flow_cache_entry *fle, **head;
173 unsigned int hash;
174 int cpu;
175
176 local_bh_disable();
177 cpu = smp_processor_id();
178
179 fle = NULL;
180 /* Packet really early in init? Making flow_cache_init a
181 * pre-smp initcall would solve this. --RR */
182 if (!flow_table(cpu))
183 goto nocache;
184
185 if (flow_hash_rnd_recalc(cpu))
186 flow_new_hash_rnd(cpu);
187 hash = flow_hash_code(key, cpu);
188
189 head = &flow_table(cpu)[hash];
190 for (fle = *head; fle; fle = fle->next) {
191 if (fle->family == family &&
192 fle->dir == dir &&
193 flow_key_compare(key, &fle->key) == 0) {
194 if (fle->genid == atomic_read(&flow_cache_genid)) {
195 void *ret = fle->object;
196
197 if (ret)
198 atomic_inc(fle->object_ref);
199 local_bh_enable();
200
201 return ret;
202 }
203 break;
204 }
205 }
206
207 if (!fle) {
208 if (flow_count(cpu) > flow_hwm)
209 flow_cache_shrink(cpu);
210
211 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
212 if (fle) {
213 fle->next = *head;
214 *head = fle;
215 fle->family = family;
216 fle->dir = dir;
217 memcpy(&fle->key, key, sizeof(*key));
218 fle->object = NULL;
219 flow_count(cpu)++;
220 }
221 }
222
223 nocache:
224 {
225 int err;
226 void *obj;
227 atomic_t *obj_ref;
228
229 err = resolver(key, family, dir, &obj, &obj_ref);
230
231 if (fle && !err) {
232 fle->genid = atomic_read(&flow_cache_genid);
233
234 if (fle->object)
235 atomic_dec(fle->object_ref);
236
237 fle->object = obj;
238 fle->object_ref = obj_ref;
239 if (obj)
240 atomic_inc(fle->object_ref);
241 }
242 local_bh_enable();
243
244 if (err)
245 obj = ERR_PTR(err);
246 return obj;
247 }
248 }
249
250 static void flow_cache_flush_tasklet(unsigned long data)
251 {
252 struct flow_flush_info *info = (void *)data;
253 int i;
254 int cpu;
255
256 cpu = smp_processor_id();
257 for (i = 0; i < flow_hash_size; i++) {
258 struct flow_cache_entry *fle;
259
260 fle = flow_table(cpu)[i];
261 for (; fle; fle = fle->next) {
262 unsigned genid = atomic_read(&flow_cache_genid);
263
264 if (!fle->object || fle->genid == genid)
265 continue;
266
267 fle->object = NULL;
268 atomic_dec(fle->object_ref);
269 }
270 }
271
272 if (atomic_dec_and_test(&info->cpuleft))
273 complete(&info->completion);
274 }
275
276 static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
277 static void flow_cache_flush_per_cpu(void *data)
278 {
279 struct flow_flush_info *info = data;
280 int cpu;
281 struct tasklet_struct *tasklet;
282
283 cpu = smp_processor_id();
284
285 tasklet = flow_flush_tasklet(cpu);
286 tasklet->data = (unsigned long)info;
287 tasklet_schedule(tasklet);
288 }
289
290 void flow_cache_flush(void)
291 {
292 struct flow_flush_info info;
293 static DEFINE_MUTEX(flow_flush_sem);
294
295 /* Don't want cpus going down or up during this. */
296 get_online_cpus();
297 mutex_lock(&flow_flush_sem);
298 atomic_set(&info.cpuleft, num_online_cpus());
299 init_completion(&info.completion);
300
301 local_bh_disable();
302 smp_call_function(flow_cache_flush_per_cpu, &info, 1, 0);
303 flow_cache_flush_tasklet((unsigned long)&info);
304 local_bh_enable();
305
306 wait_for_completion(&info.completion);
307 mutex_unlock(&flow_flush_sem);
308 put_online_cpus();
309 }
310
311 static void __devinit flow_cache_cpu_prepare(int cpu)
312 {
313 struct tasklet_struct *tasklet;
314 unsigned long order;
315
316 for (order = 0;
317 (PAGE_SIZE << order) <
318 (sizeof(struct flow_cache_entry *)*flow_hash_size);
319 order++)
320 /* NOTHING */;
321
322 flow_table(cpu) = (struct flow_cache_entry **)
323 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
324 if (!flow_table(cpu))
325 panic("NET: failed to allocate flow cache order %lu\n", order);
326
327 flow_hash_rnd_recalc(cpu) = 1;
328 flow_count(cpu) = 0;
329
330 tasklet = flow_flush_tasklet(cpu);
331 tasklet_init(tasklet, flow_cache_flush_tasklet, 0);
332 }
333
334 static int flow_cache_cpu(struct notifier_block *nfb,
335 unsigned long action,
336 void *hcpu)
337 {
338 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
339 __flow_cache_shrink((unsigned long)hcpu, 0);
340 return NOTIFY_OK;
341 }
342
343 static int __init flow_cache_init(void)
344 {
345 int i;
346
347 flow_cachep = kmem_cache_create("flow_cache",
348 sizeof(struct flow_cache_entry),
349 0, SLAB_PANIC,
350 NULL);
351 flow_hash_shift = 10;
352 flow_lwm = 2 * flow_hash_size;
353 flow_hwm = 4 * flow_hash_size;
354
355 setup_timer(&flow_hash_rnd_timer, flow_cache_new_hashrnd, 0);
356 flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
357 add_timer(&flow_hash_rnd_timer);
358
359 for_each_possible_cpu(i)
360 flow_cache_cpu_prepare(i);
361
362 hotcpu_notifier(flow_cache_cpu, 0);
363 return 0;
364 }
365
366 module_init(flow_cache_init);
367
368 EXPORT_SYMBOL(flow_cache_genid);
369 EXPORT_SYMBOL(flow_cache_lookup);
370
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