6489f4e24ecf118f98a457284d130973ca841130
[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 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 } ____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_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_HWCACHE_ALIGN|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         init_timer(&flow_hash_rnd_timer);
356         flow_hash_rnd_timer.function = flow_cache_new_hashrnd;
357         flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
358         add_timer(&flow_hash_rnd_timer);
359
360         for_each_possible_cpu(i)
361                 flow_cache_cpu_prepare(i);
362
363         hotcpu_notifier(flow_cache_cpu, 0);
364         return 0;
365 }
366
367 module_init(flow_cache_init);
368
369 EXPORT_SYMBOL(flow_cache_genid);
370 EXPORT_SYMBOL(flow_cache_lookup);