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Commit | Line | Data |
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1 | /* | |
2 | * Generic pidhash and scalable, time-bounded PID allocator | |
3 | * | |
4 | * (C) 2002-2003 Nadia Yvette Chambers, IBM | |
5 | * (C) 2004 Nadia Yvette Chambers, Oracle | |
6 | * (C) 2002-2004 Ingo Molnar, Red Hat | |
7 | * | |
8 | * pid-structures are backing objects for tasks sharing a given ID to chain | |
9 | * against. There is very little to them aside from hashing them and | |
10 | * parking tasks using given ID's on a list. | |
11 | * | |
12 | * The hash is always changed with the tasklist_lock write-acquired, | |
13 | * and the hash is only accessed with the tasklist_lock at least | |
14 | * read-acquired, so there's no additional SMP locking needed here. | |
15 | * | |
16 | * We have a list of bitmap pages, which bitmaps represent the PID space. | |
17 | * Allocating and freeing PIDs is completely lockless. The worst-case | |
18 | * allocation scenario when all but one out of 1 million PIDs possible are | |
19 | * allocated already: the scanning of 32 list entries and at most PAGE_SIZE | |
20 | * bytes. The typical fastpath is a single successful setbit. Freeing is O(1). | |
21 | * | |
22 | * Pid namespaces: | |
23 | * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc. | |
24 | * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM | |
25 | * Many thanks to Oleg Nesterov for comments and help | |
26 | * | |
27 | */ | |
28 | ||
29 | #include <linux/mm.h> | |
30 | #include <linux/export.h> | |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/rculist.h> | |
34 | #include <linux/bootmem.h> | |
35 | #include <linux/hash.h> | |
36 | #include <linux/pid_namespace.h> | |
37 | #include <linux/init_task.h> | |
38 | #include <linux/syscalls.h> | |
39 | #include <linux/proc_ns.h> | |
40 | #include <linux/proc_fs.h> | |
41 | ||
42 | #define pid_hashfn(nr, ns) \ | |
43 | hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift) | |
44 | static struct hlist_head *pid_hash; | |
45 | static unsigned int pidhash_shift = 4; | |
46 | struct pid init_struct_pid = INIT_STRUCT_PID; | |
47 | ||
48 | int pid_max = PID_MAX_DEFAULT; | |
49 | ||
50 | #define RESERVED_PIDS 300 | |
51 | ||
52 | int pid_max_min = RESERVED_PIDS + 1; | |
53 | int pid_max_max = PID_MAX_LIMIT; | |
54 | ||
55 | static inline int mk_pid(struct pid_namespace *pid_ns, | |
56 | struct pidmap *map, int off) | |
57 | { | |
58 | return (map - pid_ns->pidmap)*BITS_PER_PAGE + off; | |
59 | } | |
60 | ||
61 | #define find_next_offset(map, off) \ | |
62 | find_next_zero_bit((map)->page, BITS_PER_PAGE, off) | |
63 | ||
64 | /* | |
65 | * PID-map pages start out as NULL, they get allocated upon | |
66 | * first use and are never deallocated. This way a low pid_max | |
67 | * value does not cause lots of bitmaps to be allocated, but | |
68 | * the scheme scales to up to 4 million PIDs, runtime. | |
69 | */ | |
70 | struct pid_namespace init_pid_ns = { | |
71 | .kref = { | |
72 | .refcount = ATOMIC_INIT(2), | |
73 | }, | |
74 | .pidmap = { | |
75 | [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } | |
76 | }, | |
77 | .last_pid = 0, | |
78 | .nr_hashed = PIDNS_HASH_ADDING, | |
79 | .level = 0, | |
80 | .child_reaper = &init_task, | |
81 | .user_ns = &init_user_ns, | |
82 | .ns.inum = PROC_PID_INIT_INO, | |
83 | #ifdef CONFIG_PID_NS | |
84 | .ns.ops = &pidns_operations, | |
85 | #endif | |
86 | }; | |
87 | EXPORT_SYMBOL_GPL(init_pid_ns); | |
88 | ||
89 | /* | |
90 | * Note: disable interrupts while the pidmap_lock is held as an | |
91 | * interrupt might come in and do read_lock(&tasklist_lock). | |
92 | * | |
93 | * If we don't disable interrupts there is a nasty deadlock between | |
94 | * detach_pid()->free_pid() and another cpu that does | |
95 | * spin_lock(&pidmap_lock) followed by an interrupt routine that does | |
96 | * read_lock(&tasklist_lock); | |
97 | * | |
98 | * After we clean up the tasklist_lock and know there are no | |
99 | * irq handlers that take it we can leave the interrupts enabled. | |
100 | * For now it is easier to be safe than to prove it can't happen. | |
101 | */ | |
102 | ||
103 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); | |
104 | ||
105 | static void free_pidmap(struct upid *upid) | |
106 | { | |
107 | int nr = upid->nr; | |
108 | struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE; | |
109 | int offset = nr & BITS_PER_PAGE_MASK; | |
110 | ||
111 | clear_bit(offset, map->page); | |
112 | atomic_inc(&map->nr_free); | |
113 | } | |
114 | ||
115 | /* | |
116 | * If we started walking pids at 'base', is 'a' seen before 'b'? | |
117 | */ | |
118 | static int pid_before(int base, int a, int b) | |
119 | { | |
120 | /* | |
121 | * This is the same as saying | |
122 | * | |
123 | * (a - base + MAXUINT) % MAXUINT < (b - base + MAXUINT) % MAXUINT | |
124 | * and that mapping orders 'a' and 'b' with respect to 'base'. | |
125 | */ | |
126 | return (unsigned)(a - base) < (unsigned)(b - base); | |
127 | } | |
128 | ||
129 | /* | |
130 | * We might be racing with someone else trying to set pid_ns->last_pid | |
131 | * at the pid allocation time (there's also a sysctl for this, but racing | |
132 | * with this one is OK, see comment in kernel/pid_namespace.c about it). | |
133 | * We want the winner to have the "later" value, because if the | |
134 | * "earlier" value prevails, then a pid may get reused immediately. | |
135 | * | |
136 | * Since pids rollover, it is not sufficient to just pick the bigger | |
137 | * value. We have to consider where we started counting from. | |
138 | * | |
139 | * 'base' is the value of pid_ns->last_pid that we observed when | |
140 | * we started looking for a pid. | |
141 | * | |
142 | * 'pid' is the pid that we eventually found. | |
143 | */ | |
144 | static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid) | |
145 | { | |
146 | int prev; | |
147 | int last_write = base; | |
148 | do { | |
149 | prev = last_write; | |
150 | last_write = cmpxchg(&pid_ns->last_pid, prev, pid); | |
151 | } while ((prev != last_write) && (pid_before(base, last_write, pid))); | |
152 | } | |
153 | ||
154 | static int alloc_pidmap(struct pid_namespace *pid_ns) | |
155 | { | |
156 | int i, offset, max_scan, pid, last = pid_ns->last_pid; | |
157 | struct pidmap *map; | |
158 | ||
159 | pid = last + 1; | |
160 | if (pid >= pid_max) | |
161 | pid = RESERVED_PIDS; | |
162 | offset = pid & BITS_PER_PAGE_MASK; | |
163 | map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; | |
164 | /* | |
165 | * If last_pid points into the middle of the map->page we | |
166 | * want to scan this bitmap block twice, the second time | |
167 | * we start with offset == 0 (or RESERVED_PIDS). | |
168 | */ | |
169 | max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset; | |
170 | for (i = 0; i <= max_scan; ++i) { | |
171 | if (unlikely(!map->page)) { | |
172 | void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
173 | /* | |
174 | * Free the page if someone raced with us | |
175 | * installing it: | |
176 | */ | |
177 | spin_lock_irq(&pidmap_lock); | |
178 | if (!map->page) { | |
179 | map->page = page; | |
180 | page = NULL; | |
181 | } | |
182 | spin_unlock_irq(&pidmap_lock); | |
183 | kfree(page); | |
184 | if (unlikely(!map->page)) | |
185 | return -ENOMEM; | |
186 | } | |
187 | if (likely(atomic_read(&map->nr_free))) { | |
188 | for ( ; ; ) { | |
189 | if (!test_and_set_bit(offset, map->page)) { | |
190 | atomic_dec(&map->nr_free); | |
191 | set_last_pid(pid_ns, last, pid); | |
192 | return pid; | |
193 | } | |
194 | offset = find_next_offset(map, offset); | |
195 | if (offset >= BITS_PER_PAGE) | |
196 | break; | |
197 | pid = mk_pid(pid_ns, map, offset); | |
198 | if (pid >= pid_max) | |
199 | break; | |
200 | } | |
201 | } | |
202 | if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { | |
203 | ++map; | |
204 | offset = 0; | |
205 | } else { | |
206 | map = &pid_ns->pidmap[0]; | |
207 | offset = RESERVED_PIDS; | |
208 | if (unlikely(last == offset)) | |
209 | break; | |
210 | } | |
211 | pid = mk_pid(pid_ns, map, offset); | |
212 | } | |
213 | return -EAGAIN; | |
214 | } | |
215 | ||
216 | int next_pidmap(struct pid_namespace *pid_ns, unsigned int last) | |
217 | { | |
218 | int offset; | |
219 | struct pidmap *map, *end; | |
220 | ||
221 | if (last >= PID_MAX_LIMIT) | |
222 | return -1; | |
223 | ||
224 | offset = (last + 1) & BITS_PER_PAGE_MASK; | |
225 | map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE]; | |
226 | end = &pid_ns->pidmap[PIDMAP_ENTRIES]; | |
227 | for (; map < end; map++, offset = 0) { | |
228 | if (unlikely(!map->page)) | |
229 | continue; | |
230 | offset = find_next_bit((map)->page, BITS_PER_PAGE, offset); | |
231 | if (offset < BITS_PER_PAGE) | |
232 | return mk_pid(pid_ns, map, offset); | |
233 | } | |
234 | return -1; | |
235 | } | |
236 | ||
237 | void put_pid(struct pid *pid) | |
238 | { | |
239 | struct pid_namespace *ns; | |
240 | ||
241 | if (!pid) | |
242 | return; | |
243 | ||
244 | ns = pid->numbers[pid->level].ns; | |
245 | if ((atomic_read(&pid->count) == 1) || | |
246 | atomic_dec_and_test(&pid->count)) { | |
247 | kmem_cache_free(ns->pid_cachep, pid); | |
248 | put_pid_ns(ns); | |
249 | } | |
250 | } | |
251 | EXPORT_SYMBOL_GPL(put_pid); | |
252 | ||
253 | static void delayed_put_pid(struct rcu_head *rhp) | |
254 | { | |
255 | struct pid *pid = container_of(rhp, struct pid, rcu); | |
256 | put_pid(pid); | |
257 | } | |
258 | ||
259 | void free_pid(struct pid *pid) | |
260 | { | |
261 | /* We can be called with write_lock_irq(&tasklist_lock) held */ | |
262 | int i; | |
263 | unsigned long flags; | |
264 | ||
265 | spin_lock_irqsave(&pidmap_lock, flags); | |
266 | for (i = 0; i <= pid->level; i++) { | |
267 | struct upid *upid = pid->numbers + i; | |
268 | struct pid_namespace *ns = upid->ns; | |
269 | hlist_del_rcu(&upid->pid_chain); | |
270 | switch(--ns->nr_hashed) { | |
271 | case 2: | |
272 | case 1: | |
273 | /* When all that is left in the pid namespace | |
274 | * is the reaper wake up the reaper. The reaper | |
275 | * may be sleeping in zap_pid_ns_processes(). | |
276 | */ | |
277 | wake_up_process(ns->child_reaper); | |
278 | break; | |
279 | case PIDNS_HASH_ADDING: | |
280 | /* Handle a fork failure of the first process */ | |
281 | WARN_ON(ns->child_reaper); | |
282 | ns->nr_hashed = 0; | |
283 | /* fall through */ | |
284 | case 0: | |
285 | schedule_work(&ns->proc_work); | |
286 | break; | |
287 | } | |
288 | } | |
289 | spin_unlock_irqrestore(&pidmap_lock, flags); | |
290 | ||
291 | for (i = 0; i <= pid->level; i++) | |
292 | free_pidmap(pid->numbers + i); | |
293 | ||
294 | call_rcu(&pid->rcu, delayed_put_pid); | |
295 | } | |
296 | ||
297 | struct pid *alloc_pid(struct pid_namespace *ns) | |
298 | { | |
299 | struct pid *pid; | |
300 | enum pid_type type; | |
301 | int i, nr; | |
302 | struct pid_namespace *tmp; | |
303 | struct upid *upid; | |
304 | int retval = -ENOMEM; | |
305 | ||
306 | pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); | |
307 | if (!pid) | |
308 | return ERR_PTR(retval); | |
309 | ||
310 | tmp = ns; | |
311 | pid->level = ns->level; | |
312 | for (i = ns->level; i >= 0; i--) { | |
313 | nr = alloc_pidmap(tmp); | |
314 | if (nr < 0) { | |
315 | retval = nr; | |
316 | goto out_free; | |
317 | } | |
318 | ||
319 | pid->numbers[i].nr = nr; | |
320 | pid->numbers[i].ns = tmp; | |
321 | tmp = tmp->parent; | |
322 | } | |
323 | ||
324 | if (unlikely(is_child_reaper(pid))) { | |
325 | if (pid_ns_prepare_proc(ns)) | |
326 | goto out_free; | |
327 | } | |
328 | ||
329 | get_pid_ns(ns); | |
330 | atomic_set(&pid->count, 1); | |
331 | for (type = 0; type < PIDTYPE_MAX; ++type) | |
332 | INIT_HLIST_HEAD(&pid->tasks[type]); | |
333 | ||
334 | upid = pid->numbers + ns->level; | |
335 | spin_lock_irq(&pidmap_lock); | |
336 | if (!(ns->nr_hashed & PIDNS_HASH_ADDING)) | |
337 | goto out_unlock; | |
338 | for ( ; upid >= pid->numbers; --upid) { | |
339 | hlist_add_head_rcu(&upid->pid_chain, | |
340 | &pid_hash[pid_hashfn(upid->nr, upid->ns)]); | |
341 | upid->ns->nr_hashed++; | |
342 | } | |
343 | spin_unlock_irq(&pidmap_lock); | |
344 | ||
345 | return pid; | |
346 | ||
347 | out_unlock: | |
348 | spin_unlock_irq(&pidmap_lock); | |
349 | put_pid_ns(ns); | |
350 | ||
351 | out_free: | |
352 | while (++i <= ns->level) | |
353 | free_pidmap(pid->numbers + i); | |
354 | ||
355 | kmem_cache_free(ns->pid_cachep, pid); | |
356 | return ERR_PTR(retval); | |
357 | } | |
358 | ||
359 | void disable_pid_allocation(struct pid_namespace *ns) | |
360 | { | |
361 | spin_lock_irq(&pidmap_lock); | |
362 | ns->nr_hashed &= ~PIDNS_HASH_ADDING; | |
363 | spin_unlock_irq(&pidmap_lock); | |
364 | } | |
365 | ||
366 | struct pid *find_pid_ns(int nr, struct pid_namespace *ns) | |
367 | { | |
368 | struct upid *pnr; | |
369 | ||
370 | hlist_for_each_entry_rcu(pnr, | |
371 | &pid_hash[pid_hashfn(nr, ns)], pid_chain) | |
372 | if (pnr->nr == nr && pnr->ns == ns) | |
373 | return container_of(pnr, struct pid, | |
374 | numbers[ns->level]); | |
375 | ||
376 | return NULL; | |
377 | } | |
378 | EXPORT_SYMBOL_GPL(find_pid_ns); | |
379 | ||
380 | struct pid *find_vpid(int nr) | |
381 | { | |
382 | return find_pid_ns(nr, task_active_pid_ns(current)); | |
383 | } | |
384 | EXPORT_SYMBOL_GPL(find_vpid); | |
385 | ||
386 | /* | |
387 | * attach_pid() must be called with the tasklist_lock write-held. | |
388 | */ | |
389 | void attach_pid(struct task_struct *task, enum pid_type type) | |
390 | { | |
391 | struct pid_link *link = &task->pids[type]; | |
392 | hlist_add_head_rcu(&link->node, &link->pid->tasks[type]); | |
393 | } | |
394 | ||
395 | static void __change_pid(struct task_struct *task, enum pid_type type, | |
396 | struct pid *new) | |
397 | { | |
398 | struct pid_link *link; | |
399 | struct pid *pid; | |
400 | int tmp; | |
401 | ||
402 | link = &task->pids[type]; | |
403 | pid = link->pid; | |
404 | ||
405 | hlist_del_rcu(&link->node); | |
406 | link->pid = new; | |
407 | ||
408 | for (tmp = PIDTYPE_MAX; --tmp >= 0; ) | |
409 | if (!hlist_empty(&pid->tasks[tmp])) | |
410 | return; | |
411 | ||
412 | free_pid(pid); | |
413 | } | |
414 | ||
415 | void detach_pid(struct task_struct *task, enum pid_type type) | |
416 | { | |
417 | __change_pid(task, type, NULL); | |
418 | } | |
419 | ||
420 | void change_pid(struct task_struct *task, enum pid_type type, | |
421 | struct pid *pid) | |
422 | { | |
423 | __change_pid(task, type, pid); | |
424 | attach_pid(task, type); | |
425 | } | |
426 | ||
427 | /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ | |
428 | void transfer_pid(struct task_struct *old, struct task_struct *new, | |
429 | enum pid_type type) | |
430 | { | |
431 | new->pids[type].pid = old->pids[type].pid; | |
432 | hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node); | |
433 | } | |
434 | ||
435 | struct task_struct *pid_task(struct pid *pid, enum pid_type type) | |
436 | { | |
437 | struct task_struct *result = NULL; | |
438 | if (pid) { | |
439 | struct hlist_node *first; | |
440 | first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]), | |
441 | lockdep_tasklist_lock_is_held()); | |
442 | if (first) | |
443 | result = hlist_entry(first, struct task_struct, pids[(type)].node); | |
444 | } | |
445 | return result; | |
446 | } | |
447 | EXPORT_SYMBOL(pid_task); | |
448 | ||
449 | /* | |
450 | * Must be called under rcu_read_lock(). | |
451 | */ | |
452 | struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns) | |
453 | { | |
454 | RCU_LOCKDEP_WARN(!rcu_read_lock_held(), | |
455 | "find_task_by_pid_ns() needs rcu_read_lock() protection"); | |
456 | return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID); | |
457 | } | |
458 | ||
459 | struct task_struct *find_task_by_vpid(pid_t vnr) | |
460 | { | |
461 | return find_task_by_pid_ns(vnr, task_active_pid_ns(current)); | |
462 | } | |
463 | ||
464 | struct pid *get_task_pid(struct task_struct *task, enum pid_type type) | |
465 | { | |
466 | struct pid *pid; | |
467 | rcu_read_lock(); | |
468 | if (type != PIDTYPE_PID) | |
469 | task = task->group_leader; | |
470 | pid = get_pid(rcu_dereference(task->pids[type].pid)); | |
471 | rcu_read_unlock(); | |
472 | return pid; | |
473 | } | |
474 | EXPORT_SYMBOL_GPL(get_task_pid); | |
475 | ||
476 | struct task_struct *get_pid_task(struct pid *pid, enum pid_type type) | |
477 | { | |
478 | struct task_struct *result; | |
479 | rcu_read_lock(); | |
480 | result = pid_task(pid, type); | |
481 | if (result) | |
482 | get_task_struct(result); | |
483 | rcu_read_unlock(); | |
484 | return result; | |
485 | } | |
486 | EXPORT_SYMBOL_GPL(get_pid_task); | |
487 | ||
488 | struct pid *find_get_pid(pid_t nr) | |
489 | { | |
490 | struct pid *pid; | |
491 | ||
492 | rcu_read_lock(); | |
493 | pid = get_pid(find_vpid(nr)); | |
494 | rcu_read_unlock(); | |
495 | ||
496 | return pid; | |
497 | } | |
498 | EXPORT_SYMBOL_GPL(find_get_pid); | |
499 | ||
500 | pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) | |
501 | { | |
502 | struct upid *upid; | |
503 | pid_t nr = 0; | |
504 | ||
505 | if (pid && ns->level <= pid->level) { | |
506 | upid = &pid->numbers[ns->level]; | |
507 | if (upid->ns == ns) | |
508 | nr = upid->nr; | |
509 | } | |
510 | return nr; | |
511 | } | |
512 | EXPORT_SYMBOL_GPL(pid_nr_ns); | |
513 | ||
514 | pid_t pid_vnr(struct pid *pid) | |
515 | { | |
516 | return pid_nr_ns(pid, task_active_pid_ns(current)); | |
517 | } | |
518 | EXPORT_SYMBOL_GPL(pid_vnr); | |
519 | ||
520 | pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, | |
521 | struct pid_namespace *ns) | |
522 | { | |
523 | pid_t nr = 0; | |
524 | ||
525 | rcu_read_lock(); | |
526 | if (!ns) | |
527 | ns = task_active_pid_ns(current); | |
528 | if (likely(pid_alive(task))) { | |
529 | if (type != PIDTYPE_PID) | |
530 | task = task->group_leader; | |
531 | nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns); | |
532 | } | |
533 | rcu_read_unlock(); | |
534 | ||
535 | return nr; | |
536 | } | |
537 | EXPORT_SYMBOL(__task_pid_nr_ns); | |
538 | ||
539 | pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) | |
540 | { | |
541 | return pid_nr_ns(task_tgid(tsk), ns); | |
542 | } | |
543 | EXPORT_SYMBOL(task_tgid_nr_ns); | |
544 | ||
545 | struct pid_namespace *task_active_pid_ns(struct task_struct *tsk) | |
546 | { | |
547 | return ns_of_pid(task_pid(tsk)); | |
548 | } | |
549 | EXPORT_SYMBOL_GPL(task_active_pid_ns); | |
550 | ||
551 | /* | |
552 | * Used by proc to find the first pid that is greater than or equal to nr. | |
553 | * | |
554 | * If there is a pid at nr this function is exactly the same as find_pid_ns. | |
555 | */ | |
556 | struct pid *find_ge_pid(int nr, struct pid_namespace *ns) | |
557 | { | |
558 | struct pid *pid; | |
559 | ||
560 | do { | |
561 | pid = find_pid_ns(nr, ns); | |
562 | if (pid) | |
563 | break; | |
564 | nr = next_pidmap(ns, nr); | |
565 | } while (nr > 0); | |
566 | ||
567 | return pid; | |
568 | } | |
569 | ||
570 | /* | |
571 | * The pid hash table is scaled according to the amount of memory in the | |
572 | * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or | |
573 | * more. | |
574 | */ | |
575 | void __init pidhash_init(void) | |
576 | { | |
577 | unsigned int i, pidhash_size; | |
578 | ||
579 | pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18, | |
580 | HASH_EARLY | HASH_SMALL, | |
581 | &pidhash_shift, NULL, | |
582 | 0, 4096); | |
583 | pidhash_size = 1U << pidhash_shift; | |
584 | ||
585 | for (i = 0; i < pidhash_size; i++) | |
586 | INIT_HLIST_HEAD(&pid_hash[i]); | |
587 | } | |
588 | ||
589 | void __init pidmap_init(void) | |
590 | { | |
591 | /* Verify no one has done anything silly: */ | |
592 | BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING); | |
593 | ||
594 | /* bump default and minimum pid_max based on number of cpus */ | |
595 | pid_max = min(pid_max_max, max_t(int, pid_max, | |
596 | PIDS_PER_CPU_DEFAULT * num_possible_cpus())); | |
597 | pid_max_min = max_t(int, pid_max_min, | |
598 | PIDS_PER_CPU_MIN * num_possible_cpus()); | |
599 | pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min); | |
600 | ||
601 | init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
602 | /* Reserve PID 0. We never call free_pidmap(0) */ | |
603 | set_bit(0, init_pid_ns.pidmap[0].page); | |
604 | atomic_dec(&init_pid_ns.pidmap[0].nr_free); | |
605 | ||
606 | init_pid_ns.pid_cachep = KMEM_CACHE(pid, | |
607 | SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); | |
608 | } |