arm: tegra: enterprise: Controls for 3d barrier
[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 <linux/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         struct net                      *net;
34         u16                             family;
35         u8                              dir;
36         u32                             genid;
37         struct flowi                    key;
38         struct flow_cache_object        *object;
39 };
40
41 struct flow_cache_percpu {
42         struct hlist_head               *hash_table;
43         int                             hash_count;
44         u32                             hash_rnd;
45         int                             hash_rnd_recalc;
46         struct tasklet_struct           flush_tasklet;
47 };
48
49 struct flow_flush_info {
50         struct flow_cache               *cache;
51         atomic_t                        cpuleft;
52         struct completion               completion;
53 };
54
55 struct flow_cache {
56         u32                             hash_shift;
57         struct flow_cache_percpu __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 EXPORT_SYMBOL(flow_cache_genid);
66 static struct flow_cache flow_cache_global;
67 static struct kmem_cache *flow_cachep __read_mostly;
68
69 static DEFINE_SPINLOCK(flow_cache_gc_lock);
70 static LIST_HEAD(flow_cache_gc_list);
71
72 #define flow_cache_hash_size(cache)     (1 << (cache)->hash_shift)
73 #define FLOW_HASH_RND_PERIOD            (10 * 60 * HZ)
74
75 static void flow_cache_new_hashrnd(unsigned long arg)
76 {
77         struct flow_cache *fc = (void *) arg;
78         int i;
79
80         for_each_possible_cpu(i)
81                 per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
82
83         fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
84         add_timer(&fc->rnd_timer);
85 }
86
87 static int flow_entry_valid(struct flow_cache_entry *fle)
88 {
89         if (atomic_read(&flow_cache_genid) != fle->genid)
90                 return 0;
91         if (fle->object && !fle->object->ops->check(fle->object))
92                 return 0;
93         return 1;
94 }
95
96 static void flow_entry_kill(struct flow_cache_entry *fle)
97 {
98         if (fle->object)
99                 fle->object->ops->delete(fle->object);
100         kmem_cache_free(flow_cachep, fle);
101 }
102
103 static void flow_cache_gc_task(struct work_struct *work)
104 {
105         struct list_head gc_list;
106         struct flow_cache_entry *fce, *n;
107
108         INIT_LIST_HEAD(&gc_list);
109         spin_lock_bh(&flow_cache_gc_lock);
110         list_splice_tail_init(&flow_cache_gc_list, &gc_list);
111         spin_unlock_bh(&flow_cache_gc_lock);
112
113         list_for_each_entry_safe(fce, n, &gc_list, u.gc_list)
114                 flow_entry_kill(fce);
115 }
116 static DECLARE_WORK(flow_cache_gc_work, flow_cache_gc_task);
117
118 static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
119                                      int deleted, struct list_head *gc_list)
120 {
121         if (deleted) {
122                 fcp->hash_count -= deleted;
123                 spin_lock_bh(&flow_cache_gc_lock);
124                 list_splice_tail(gc_list, &flow_cache_gc_list);
125                 spin_unlock_bh(&flow_cache_gc_lock);
126                 schedule_work(&flow_cache_gc_work);
127         }
128 }
129
130 static void __flow_cache_shrink(struct flow_cache *fc,
131                                 struct flow_cache_percpu *fcp,
132                                 int shrink_to)
133 {
134         struct flow_cache_entry *fle;
135         struct hlist_node *entry, *tmp;
136         LIST_HEAD(gc_list);
137         int i, deleted = 0;
138
139         for (i = 0; i < flow_cache_hash_size(fc); i++) {
140                 int saved = 0;
141
142                 hlist_for_each_entry_safe(fle, entry, tmp,
143                                           &fcp->hash_table[i], u.hlist) {
144                         if (saved < shrink_to &&
145                             flow_entry_valid(fle)) {
146                                 saved++;
147                         } else {
148                                 deleted++;
149                                 hlist_del(&fle->u.hlist);
150                                 list_add_tail(&fle->u.gc_list, &gc_list);
151                         }
152                 }
153         }
154
155         flow_cache_queue_garbage(fcp, deleted, &gc_list);
156 }
157
158 static void flow_cache_shrink(struct flow_cache *fc,
159                               struct flow_cache_percpu *fcp)
160 {
161         int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
162
163         __flow_cache_shrink(fc, fcp, shrink_to);
164 }
165
166 static void flow_new_hash_rnd(struct flow_cache *fc,
167                               struct flow_cache_percpu *fcp)
168 {
169         get_random_bytes(&fcp->hash_rnd, sizeof(u32));
170         fcp->hash_rnd_recalc = 0;
171         __flow_cache_shrink(fc, fcp, 0);
172 }
173
174 static u32 flow_hash_code(struct flow_cache *fc,
175                           struct flow_cache_percpu *fcp,
176                           const struct flowi *key,
177                           size_t keysize)
178 {
179         const u32 *k = (const u32 *) key;
180         const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
181
182         return jhash2(k, length, fcp->hash_rnd)
183                 & (flow_cache_hash_size(fc) - 1);
184 }
185
186 /* I hear what you're saying, use memcmp.  But memcmp cannot make
187  * important assumptions that we can here, such as alignment.
188  */
189 static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
190                             size_t keysize)
191 {
192         const flow_compare_t *k1, *k1_lim, *k2;
193
194         k1 = (const flow_compare_t *) key1;
195         k1_lim = k1 + keysize;
196
197         k2 = (const flow_compare_t *) key2;
198
199         do {
200                 if (*k1++ != *k2++)
201                         return 1;
202         } while (k1 < k1_lim);
203
204         return 0;
205 }
206
207 struct flow_cache_object *
208 flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
209                   flow_resolve_t resolver, void *ctx)
210 {
211         struct flow_cache *fc = &flow_cache_global;
212         struct flow_cache_percpu *fcp;
213         struct flow_cache_entry *fle, *tfle;
214         struct hlist_node *entry;
215         struct flow_cache_object *flo;
216         size_t keysize;
217         unsigned int hash;
218
219         local_bh_disable();
220         fcp = this_cpu_ptr(fc->percpu);
221
222         fle = NULL;
223         flo = NULL;
224
225         keysize = flow_key_size(family);
226         if (!keysize)
227                 goto nocache;
228
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, keysize);
238         hlist_for_each_entry(tfle, entry, &fcp->hash_table[hash], u.hlist) {
239                 if (tfle->net == net &&
240                     tfle->family == family &&
241                     tfle->dir == dir &&
242                     flow_key_compare(key, &tfle->key, keysize) == 0) {
243                         fle = tfle;
244                         break;
245                 }
246         }
247
248         if (unlikely(!fle)) {
249                 if (fcp->hash_count > fc->high_watermark)
250                         flow_cache_shrink(fc, fcp);
251
252                 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
253                 if (fle) {
254                         fle->net = net;
255                         fle->family = family;
256                         fle->dir = dir;
257                         memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
258                         fle->object = NULL;
259                         hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
260                         fcp->hash_count++;
261                 }
262         } else if (likely(fle->genid == atomic_read(&flow_cache_genid))) {
263                 flo = fle->object;
264                 if (!flo)
265                         goto ret_object;
266                 flo = flo->ops->get(flo);
267                 if (flo)
268                         goto ret_object;
269         } else if (fle->object) {
270                 flo = fle->object;
271                 flo->ops->delete(flo);
272                 fle->object = NULL;
273         }
274
275 nocache:
276         flo = NULL;
277         if (fle) {
278                 flo = fle->object;
279                 fle->object = NULL;
280         }
281         flo = resolver(net, key, family, dir, flo, ctx);
282         if (fle) {
283                 fle->genid = atomic_read(&flow_cache_genid);
284                 if (!IS_ERR(flo))
285                         fle->object = flo;
286                 else
287                         fle->genid--;
288         } else {
289                 if (flo && !IS_ERR(flo))
290                         flo->ops->delete(flo);
291         }
292 ret_object:
293         local_bh_enable();
294         return flo;
295 }
296 EXPORT_SYMBOL(flow_cache_lookup);
297
298 static void flow_cache_flush_tasklet(unsigned long data)
299 {
300         struct flow_flush_info *info = (void *)data;
301         struct flow_cache *fc = info->cache;
302         struct flow_cache_percpu *fcp;
303         struct flow_cache_entry *fle;
304         struct hlist_node *entry, *tmp;
305         LIST_HEAD(gc_list);
306         int i, deleted = 0;
307
308         fcp = this_cpu_ptr(fc->percpu);
309         for (i = 0; i < flow_cache_hash_size(fc); i++) {
310                 hlist_for_each_entry_safe(fle, entry, tmp,
311                                           &fcp->hash_table[i], u.hlist) {
312                         if (flow_entry_valid(fle))
313                                 continue;
314
315                         deleted++;
316                         hlist_del(&fle->u.hlist);
317                         list_add_tail(&fle->u.gc_list, &gc_list);
318                 }
319         }
320
321         flow_cache_queue_garbage(fcp, deleted, &gc_list);
322
323         if (atomic_dec_and_test(&info->cpuleft))
324                 complete(&info->completion);
325 }
326
327 static void flow_cache_flush_per_cpu(void *data)
328 {
329         struct flow_flush_info *info = data;
330         int cpu;
331         struct tasklet_struct *tasklet;
332
333         cpu = smp_processor_id();
334         tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
335         tasklet->data = (unsigned long)info;
336         tasklet_schedule(tasklet);
337 }
338
339 void flow_cache_flush(void)
340 {
341         struct flow_flush_info info;
342         static DEFINE_MUTEX(flow_flush_sem);
343
344         /* Don't want cpus going down or up during this. */
345         get_online_cpus();
346         mutex_lock(&flow_flush_sem);
347         info.cache = &flow_cache_global;
348         atomic_set(&info.cpuleft, num_online_cpus());
349         init_completion(&info.completion);
350
351         local_bh_disable();
352         smp_call_function(flow_cache_flush_per_cpu, &info, 0);
353         flow_cache_flush_tasklet((unsigned long)&info);
354         local_bh_enable();
355
356         wait_for_completion(&info.completion);
357         mutex_unlock(&flow_flush_sem);
358         put_online_cpus();
359 }
360
361 static int __cpuinit flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
362 {
363         struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
364         size_t sz = sizeof(struct hlist_head) * flow_cache_hash_size(fc);
365
366         if (!fcp->hash_table) {
367                 fcp->hash_table = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu));
368                 if (!fcp->hash_table) {
369                         pr_err("NET: failed to allocate flow cache sz %zu\n", sz);
370                         return -ENOMEM;
371                 }
372                 fcp->hash_rnd_recalc = 1;
373                 fcp->hash_count = 0;
374                 tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
375         }
376         return 0;
377 }
378
379 static int __cpuinit flow_cache_cpu(struct notifier_block *nfb,
380                           unsigned long action,
381                           void *hcpu)
382 {
383         struct flow_cache *fc = container_of(nfb, struct flow_cache, hotcpu_notifier);
384         int res, cpu = (unsigned long) hcpu;
385         struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
386
387         switch (action) {
388         case CPU_UP_PREPARE:
389         case CPU_UP_PREPARE_FROZEN:
390                 res = flow_cache_cpu_prepare(fc, cpu);
391                 if (res)
392                         return notifier_from_errno(res);
393                 break;
394         case CPU_DEAD:
395         case CPU_DEAD_FROZEN:
396                 __flow_cache_shrink(fc, fcp, 0);
397                 break;
398         }
399         return NOTIFY_OK;
400 }
401
402 static int __init flow_cache_init(struct flow_cache *fc)
403 {
404         int i;
405
406         fc->hash_shift = 10;
407         fc->low_watermark = 2 * flow_cache_hash_size(fc);
408         fc->high_watermark = 4 * flow_cache_hash_size(fc);
409
410         fc->percpu = alloc_percpu(struct flow_cache_percpu);
411         if (!fc->percpu)
412                 return -ENOMEM;
413
414         for_each_online_cpu(i) {
415                 if (flow_cache_cpu_prepare(fc, i))
416                         return -ENOMEM;
417         }
418         fc->hotcpu_notifier = (struct notifier_block){
419                 .notifier_call = flow_cache_cpu,
420         };
421         register_hotcpu_notifier(&fc->hotcpu_notifier);
422
423         setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
424                     (unsigned long) fc);
425         fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
426         add_timer(&fc->rnd_timer);
427
428         return 0;
429 }
430
431 static int __init flow_cache_init_global(void)
432 {
433         flow_cachep = kmem_cache_create("flow_cache",
434                                         sizeof(struct flow_cache_entry),
435                                         0, SLAB_PANIC, NULL);
436
437         return flow_cache_init(&flow_cache_global);
438 }
439
440 module_init(flow_cache_init_global);