645241165e6cfce76283f76eceb9bca0de8ace3e
[linux-2.6.git] / net / core / flow.c
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         struct flowi            key;
34         u32                     genid;
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 kmem_cache_t *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 } ____cacheline_aligned;
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_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
111 static 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
118 static 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
126 static 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)
135 typedef u64 flow_compare_t;
136 #else
137 typedef u32 flow_compare_t;
138 #endif
139
140 extern 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  */
146 static 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
167 void *flow_cache_lookup(struct flowi *key, u16 family, u8 dir,
168                         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
221 nocache:
222         {
223                 void *obj;
224                 atomic_t *obj_ref;
225
226                 resolver(key, family, dir, &obj, &obj_ref);
227
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
245 static 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
271 static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
272 static 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
285 void flow_cache_flush(void)
286 {
287         struct flow_flush_info info;
288         static DEFINE_MUTEX(flow_flush_sem);
289
290         /* Don't want cpus going down or up during this. */
291         lock_cpu_hotplug();
292         mutex_lock(&flow_flush_sem);
293         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);
302         mutex_unlock(&flow_flush_sem);
303         unlock_cpu_hotplug();
304 }
305
306 static 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 **)
318                 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
319         if (!flow_table(cpu))
320                 panic("NET: failed to allocate flow cache order %lu\n", order);
321
322         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
330 static 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
340 static 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),
346                                         0, SLAB_HWCACHE_ALIGN,
347                                         NULL, NULL);
348
349         if (!flow_cachep)
350                 panic("NET: failed to allocate flow cache slab\n");
351
352         flow_hash_shift = 10;
353         flow_lwm = 2 * flow_hash_size;
354         flow_hwm = 4 * flow_hash_size;
355
356         init_timer(&flow_hash_rnd_timer);
357         flow_hash_rnd_timer.function = flow_cache_new_hashrnd;
358         flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
359         add_timer(&flow_hash_rnd_timer);
360
361         for_each_possible_cpu(i)
362                 flow_cache_cpu_prepare(i);
363
364         hotcpu_notifier(flow_cache_cpu, 0);
365         return 0;
366 }
367
368 module_init(flow_cache_init);
369
370 EXPORT_SYMBOL(flow_cache_genid);
371 EXPORT_SYMBOL(flow_cache_lookup);