net: rtnetlink: decouple rtnetlink address families from real address families
[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 <linux/security.h>
27
28 struct flow_cache_entry {
29         union {
30                 struct hlist_node       hlist;
31                 struct list_head        gc_list;
32         } u;
33         u16                             family;
34         u8                              dir;
35         u32                             genid;
36         struct flowi                    key;
37         struct flow_cache_object        *object;
38 };
39
40 struct flow_cache_percpu {
41         struct hlist_head               *hash_table;
42         int                             hash_count;
43         u32                             hash_rnd;
44         int                             hash_rnd_recalc;
45         struct tasklet_struct           flush_tasklet;
46 };
47
48 struct flow_flush_info {
49         struct flow_cache               *cache;
50         atomic_t                        cpuleft;
51         struct completion               completion;
52 };
53
54 struct flow_cache {
55         u32                             hash_shift;
56         unsigned long                   order;
57         struct flow_cache_percpu        *percpu;
58         struct notifier_block           hotcpu_notifier;
59         int                             low_watermark;
60         int                             high_watermark;
61         struct timer_list               rnd_timer;
62 };
63
64 atomic_t flow_cache_genid = ATOMIC_INIT(0);
65 static struct flow_cache flow_cache_global;
66 static struct kmem_cache *flow_cachep;
67
68 static DEFINE_SPINLOCK(flow_cache_gc_lock);
69 static LIST_HEAD(flow_cache_gc_list);
70
71 #define flow_cache_hash_size(cache)     (1 << (cache)->hash_shift)
72 #define FLOW_HASH_RND_PERIOD            (10 * 60 * HZ)
73
74 static void flow_cache_new_hashrnd(unsigned long arg)
75 {
76         struct flow_cache *fc = (void *) arg;
77         int i;
78
79         for_each_possible_cpu(i)
80                 per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
81
82         fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
83         add_timer(&fc->rnd_timer);
84 }
85
86 static int flow_entry_valid(struct flow_cache_entry *fle)
87 {
88         if (atomic_read(&flow_cache_genid) != fle->genid)
89                 return 0;
90         if (fle->object && !fle->object->ops->check(fle->object))
91                 return 0;
92         return 1;
93 }
94
95 static void flow_entry_kill(struct flow_cache_entry *fle)
96 {
97         if (fle->object)
98                 fle->object->ops->delete(fle->object);
99         kmem_cache_free(flow_cachep, fle);
100 }
101
102 static void flow_cache_gc_task(struct work_struct *work)
103 {
104         struct list_head gc_list;
105         struct flow_cache_entry *fce, *n;
106
107         INIT_LIST_HEAD(&gc_list);
108         spin_lock_bh(&flow_cache_gc_lock);
109         list_splice_tail_init(&flow_cache_gc_list, &gc_list);
110         spin_unlock_bh(&flow_cache_gc_lock);
111
112         list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
113                 flow_entry_kill(fce);
114 }
115 static DECLARE_WORK(flow_cache_gc_work, flow_cache_gc_task);
116
117 static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
118                                      int deleted, struct list_head *gc_list)
119 {
120         if (deleted) {
121                 fcp->hash_count -= deleted;
122                 spin_lock_bh(&flow_cache_gc_lock);
123                 list_splice_tail(gc_list, &flow_cache_gc_list);
124                 spin_unlock_bh(&flow_cache_gc_lock);
125                 schedule_work(&flow_cache_gc_work);
126         }
127 }
128
129 static void __flow_cache_shrink(struct flow_cache *fc,
130                                 struct flow_cache_percpu *fcp,
131                                 int shrink_to)
132 {
133         struct flow_cache_entry *fle;
134         struct hlist_node *entry, *tmp;
135         LIST_HEAD(gc_list);
136         int i, deleted = 0;
137
138         for (i = 0; i < flow_cache_hash_size(fc); i++) {
139                 int saved = 0;
140
141                 hlist_for_each_entry_safe(fle, entry, tmp,
142                                           &fcp->hash_table[i], u.hlist) {
143                         if (saved < shrink_to &&
144                             flow_entry_valid(fle)) {
145                                 saved++;
146                         } else {
147                                 deleted++;
148                                 hlist_del(&fle->u.hlist);
149                                 list_add_tail(&fle->u.gc_list, &gc_list);
150                         }
151                 }
152         }
153
154         flow_cache_queue_garbage(fcp, deleted, &gc_list);
155 }
156
157 static void flow_cache_shrink(struct flow_cache *fc,
158                               struct flow_cache_percpu *fcp)
159 {
160         int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
161
162         __flow_cache_shrink(fc, fcp, shrink_to);
163 }
164
165 static void flow_new_hash_rnd(struct flow_cache *fc,
166                               struct flow_cache_percpu *fcp)
167 {
168         get_random_bytes(&fcp->hash_rnd, sizeof(u32));
169         fcp->hash_rnd_recalc = 0;
170         __flow_cache_shrink(fc, fcp, 0);
171 }
172
173 static u32 flow_hash_code(struct flow_cache *fc,
174                           struct flow_cache_percpu *fcp,
175                           struct flowi *key)
176 {
177         u32 *k = (u32 *) key;
178
179         return (jhash2(k, (sizeof(*key) / sizeof(u32)), fcp->hash_rnd)
180                 & (flow_cache_hash_size(fc) - 1));
181 }
182
183 #if (BITS_PER_LONG == 64)
184 typedef u64 flow_compare_t;
185 #else
186 typedef u32 flow_compare_t;
187 #endif
188
189 /* I hear what you're saying, use memcmp.  But memcmp cannot make
190  * important assumptions that we can here, such as alignment and
191  * constant size.
192  */
193 static int flow_key_compare(struct flowi *key1, struct flowi *key2)
194 {
195         flow_compare_t *k1, *k1_lim, *k2;
196         const int n_elem = sizeof(struct flowi) / sizeof(flow_compare_t);
197
198         BUILD_BUG_ON(sizeof(struct flowi) % sizeof(flow_compare_t));
199
200         k1 = (flow_compare_t *) key1;
201         k1_lim = k1 + n_elem;
202
203         k2 = (flow_compare_t *) key2;
204
205         do {
206                 if (*k1++ != *k2++)
207                         return 1;
208         } while (k1 < k1_lim);
209
210         return 0;
211 }
212
213 struct flow_cache_object *
214 flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
215                   flow_resolve_t resolver, void *ctx)
216 {
217         struct flow_cache *fc = &flow_cache_global;
218         struct flow_cache_percpu *fcp;
219         struct flow_cache_entry *fle, *tfle;
220         struct hlist_node *entry;
221         struct flow_cache_object *flo;
222         unsigned int hash;
223
224         local_bh_disable();
225         fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
226
227         fle = NULL;
228         flo = NULL;
229         /* Packet really early in init?  Making flow_cache_init a
230          * pre-smp initcall would solve this.  --RR */
231         if (!fcp->hash_table)
232                 goto nocache;
233
234         if (fcp->hash_rnd_recalc)
235                 flow_new_hash_rnd(fc, fcp);
236
237         hash = flow_hash_code(fc, fcp, key);
238         hlist_for_each_entry(tfle, entry, &fcp->hash_table[hash], u.hlist) {
239                 if (tfle->family == family &&
240                     tfle->dir == dir &&
241                     flow_key_compare(key, &tfle->key) == 0) {
242                         fle = tfle;
243                         break;
244                 }
245         }
246
247         if (unlikely(!fle)) {
248                 if (fcp->hash_count > fc->high_watermark)
249                         flow_cache_shrink(fc, fcp);
250
251                 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
252                 if (fle) {
253                         fle->family = family;
254                         fle->dir = dir;
255                         memcpy(&fle->key, key, sizeof(*key));
256                         fle->object = NULL;
257                         hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
258                         fcp->hash_count++;
259                 }
260         } else if (likely(fle->genid == atomic_read(&flow_cache_genid))) {
261                 flo = fle->object;
262                 if (!flo)
263                         goto ret_object;
264                 flo = flo->ops->get(flo);
265                 if (flo)
266                         goto ret_object;
267         } else if (fle->object) {
268                 flo = fle->object;
269                 flo->ops->delete(flo);
270                 fle->object = NULL;
271         }
272
273 nocache:
274         flo = NULL;
275         if (fle) {
276                 flo = fle->object;
277                 fle->object = NULL;
278         }
279         flo = resolver(net, key, family, dir, flo, ctx);
280         if (fle) {
281                 fle->genid = atomic_read(&flow_cache_genid);
282                 if (!IS_ERR(flo))
283                         fle->object = flo;
284                 else
285                         fle->genid--;
286         } else {
287                 if (flo && !IS_ERR(flo))
288                         flo->ops->delete(flo);
289         }
290 ret_object:
291         local_bh_enable();
292         return flo;
293 }
294
295 static void flow_cache_flush_tasklet(unsigned long data)
296 {
297         struct flow_flush_info *info = (void *)data;
298         struct flow_cache *fc = info->cache;
299         struct flow_cache_percpu *fcp;
300         struct flow_cache_entry *fle;
301         struct hlist_node *entry, *tmp;
302         LIST_HEAD(gc_list);
303         int i, deleted = 0;
304
305         fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
306         for (i = 0; i < flow_cache_hash_size(fc); i++) {
307                 hlist_for_each_entry_safe(fle, entry, tmp,
308                                           &fcp->hash_table[i], u.hlist) {
309                         if (flow_entry_valid(fle))
310                                 continue;
311
312                         deleted++;
313                         hlist_del(&fle->u.hlist);
314                         list_add_tail(&fle->u.gc_list, &gc_list);
315                 }
316         }
317
318         flow_cache_queue_garbage(fcp, deleted, &gc_list);
319
320         if (atomic_dec_and_test(&info->cpuleft))
321                 complete(&info->completion);
322 }
323
324 static void flow_cache_flush_per_cpu(void *data)
325 {
326         struct flow_flush_info *info = data;
327         int cpu;
328         struct tasklet_struct *tasklet;
329
330         cpu = smp_processor_id();
331         tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
332         tasklet->data = (unsigned long)info;
333         tasklet_schedule(tasklet);
334 }
335
336 void flow_cache_flush(void)
337 {
338         struct flow_flush_info info;
339         static DEFINE_MUTEX(flow_flush_sem);
340
341         /* Don't want cpus going down or up during this. */
342         get_online_cpus();
343         mutex_lock(&flow_flush_sem);
344         info.cache = &flow_cache_global;
345         atomic_set(&info.cpuleft, num_online_cpus());
346         init_completion(&info.completion);
347
348         local_bh_disable();
349         smp_call_function(flow_cache_flush_per_cpu, &info, 0);
350         flow_cache_flush_tasklet((unsigned long)&info);
351         local_bh_enable();
352
353         wait_for_completion(&info.completion);
354         mutex_unlock(&flow_flush_sem);
355         put_online_cpus();
356 }
357
358 static void __init flow_cache_cpu_prepare(struct flow_cache *fc,
359                                           struct flow_cache_percpu *fcp)
360 {
361         fcp->hash_table = (struct hlist_head *)
362                 __get_free_pages(GFP_KERNEL|__GFP_ZERO, fc->order);
363         if (!fcp->hash_table)
364                 panic("NET: failed to allocate flow cache order %lu\n", fc->order);
365
366         fcp->hash_rnd_recalc = 1;
367         fcp->hash_count = 0;
368         tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
369 }
370
371 static int flow_cache_cpu(struct notifier_block *nfb,
372                           unsigned long action,
373                           void *hcpu)
374 {
375         struct flow_cache *fc = container_of(nfb, struct flow_cache, hotcpu_notifier);
376         int cpu = (unsigned long) hcpu;
377         struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
378
379         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
380                 __flow_cache_shrink(fc, fcp, 0);
381         return NOTIFY_OK;
382 }
383
384 static int flow_cache_init(struct flow_cache *fc)
385 {
386         unsigned long order;
387         int i;
388
389         fc->hash_shift = 10;
390         fc->low_watermark = 2 * flow_cache_hash_size(fc);
391         fc->high_watermark = 4 * flow_cache_hash_size(fc);
392
393         for (order = 0;
394              (PAGE_SIZE << order) <
395                      (sizeof(struct hlist_head)*flow_cache_hash_size(fc));
396              order++)
397                 /* NOTHING */;
398         fc->order = order;
399         fc->percpu = alloc_percpu(struct flow_cache_percpu);
400
401         setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
402                     (unsigned long) fc);
403         fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
404         add_timer(&fc->rnd_timer);
405
406         for_each_possible_cpu(i)
407                 flow_cache_cpu_prepare(fc, per_cpu_ptr(fc->percpu, i));
408
409         fc->hotcpu_notifier = (struct notifier_block){
410                 .notifier_call = flow_cache_cpu,
411         };
412         register_hotcpu_notifier(&fc->hotcpu_notifier);
413
414         return 0;
415 }
416
417 static int __init flow_cache_init_global(void)
418 {
419         flow_cachep = kmem_cache_create("flow_cache",
420                                         sizeof(struct flow_cache_entry),
421                                         0, SLAB_PANIC, NULL);
422
423         return flow_cache_init(&flow_cache_global);
424 }
425
426 module_init(flow_cache_init_global);
427
428 EXPORT_SYMBOL(flow_cache_genid);
429 EXPORT_SYMBOL(flow_cache_lookup);