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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Generic pidhash and scalable, time-bounded PID allocator | |
3 | * | |
4 | * (C) 2002-2003 William Irwin, IBM | |
5 | * (C) 2004 William Irwin, 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). | |
30e49c26 PE |
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 | * | |
1da177e4 LT |
27 | */ |
28 | ||
29 | #include <linux/mm.h> | |
30 | #include <linux/module.h> | |
31 | #include <linux/slab.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/bootmem.h> | |
34 | #include <linux/hash.h> | |
61a58c6c | 35 | #include <linux/pid_namespace.h> |
820e45db | 36 | #include <linux/init_task.h> |
3eb07c8c | 37 | #include <linux/syscalls.h> |
1da177e4 | 38 | |
8ef047aa PE |
39 | #define pid_hashfn(nr, ns) \ |
40 | hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift) | |
92476d7f | 41 | static struct hlist_head *pid_hash; |
1da177e4 | 42 | static int pidhash_shift; |
820e45db | 43 | struct pid init_struct_pid = INIT_STRUCT_PID; |
1da177e4 LT |
44 | |
45 | int pid_max = PID_MAX_DEFAULT; | |
1da177e4 LT |
46 | |
47 | #define RESERVED_PIDS 300 | |
48 | ||
49 | int pid_max_min = RESERVED_PIDS + 1; | |
50 | int pid_max_max = PID_MAX_LIMIT; | |
51 | ||
1da177e4 LT |
52 | #define BITS_PER_PAGE (PAGE_SIZE*8) |
53 | #define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1) | |
3fbc9648 | 54 | |
61a58c6c SB |
55 | static inline int mk_pid(struct pid_namespace *pid_ns, |
56 | struct pidmap *map, int off) | |
3fbc9648 | 57 | { |
61a58c6c | 58 | return (map - pid_ns->pidmap)*BITS_PER_PAGE + off; |
3fbc9648 SB |
59 | } |
60 | ||
1da177e4 LT |
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 | */ | |
61a58c6c | 70 | struct pid_namespace init_pid_ns = { |
9a575a92 CLG |
71 | .kref = { |
72 | .refcount = ATOMIC_INIT(2), | |
73 | }, | |
3fbc9648 SB |
74 | .pidmap = { |
75 | [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } | |
76 | }, | |
84d73786 | 77 | .last_pid = 0, |
faacbfd3 PE |
78 | .level = 0, |
79 | .child_reaper = &init_task, | |
3fbc9648 | 80 | }; |
198fe21b | 81 | EXPORT_SYMBOL_GPL(init_pid_ns); |
1da177e4 | 82 | |
b461cc03 | 83 | int is_container_init(struct task_struct *tsk) |
b460cbc5 | 84 | { |
b461cc03 PE |
85 | int ret = 0; |
86 | struct pid *pid; | |
87 | ||
88 | rcu_read_lock(); | |
89 | pid = task_pid(tsk); | |
90 | if (pid != NULL && pid->numbers[pid->level].nr == 1) | |
91 | ret = 1; | |
92 | rcu_read_unlock(); | |
93 | ||
94 | return ret; | |
b460cbc5 | 95 | } |
b461cc03 | 96 | EXPORT_SYMBOL(is_container_init); |
b460cbc5 | 97 | |
92476d7f EB |
98 | /* |
99 | * Note: disable interrupts while the pidmap_lock is held as an | |
100 | * interrupt might come in and do read_lock(&tasklist_lock). | |
101 | * | |
102 | * If we don't disable interrupts there is a nasty deadlock between | |
103 | * detach_pid()->free_pid() and another cpu that does | |
104 | * spin_lock(&pidmap_lock) followed by an interrupt routine that does | |
105 | * read_lock(&tasklist_lock); | |
106 | * | |
107 | * After we clean up the tasklist_lock and know there are no | |
108 | * irq handlers that take it we can leave the interrupts enabled. | |
109 | * For now it is easier to be safe than to prove it can't happen. | |
110 | */ | |
3fbc9648 | 111 | |
1da177e4 LT |
112 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); |
113 | ||
7ad5b3a5 | 114 | static void free_pidmap(struct pid_namespace *pid_ns, int pid) |
1da177e4 | 115 | { |
61a58c6c | 116 | struct pidmap *map = pid_ns->pidmap + pid / BITS_PER_PAGE; |
1da177e4 LT |
117 | int offset = pid & BITS_PER_PAGE_MASK; |
118 | ||
119 | clear_bit(offset, map->page); | |
120 | atomic_inc(&map->nr_free); | |
121 | } | |
122 | ||
61a58c6c | 123 | static int alloc_pidmap(struct pid_namespace *pid_ns) |
1da177e4 | 124 | { |
61a58c6c | 125 | int i, offset, max_scan, pid, last = pid_ns->last_pid; |
6a1f3b84 | 126 | struct pidmap *map; |
1da177e4 LT |
127 | |
128 | pid = last + 1; | |
129 | if (pid >= pid_max) | |
130 | pid = RESERVED_PIDS; | |
131 | offset = pid & BITS_PER_PAGE_MASK; | |
61a58c6c | 132 | map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; |
1da177e4 LT |
133 | max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset; |
134 | for (i = 0; i <= max_scan; ++i) { | |
135 | if (unlikely(!map->page)) { | |
3fbc9648 | 136 | void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
1da177e4 LT |
137 | /* |
138 | * Free the page if someone raced with us | |
139 | * installing it: | |
140 | */ | |
92476d7f | 141 | spin_lock_irq(&pidmap_lock); |
1da177e4 | 142 | if (map->page) |
3fbc9648 | 143 | kfree(page); |
1da177e4 | 144 | else |
3fbc9648 | 145 | map->page = page; |
92476d7f | 146 | spin_unlock_irq(&pidmap_lock); |
1da177e4 LT |
147 | if (unlikely(!map->page)) |
148 | break; | |
149 | } | |
150 | if (likely(atomic_read(&map->nr_free))) { | |
151 | do { | |
152 | if (!test_and_set_bit(offset, map->page)) { | |
153 | atomic_dec(&map->nr_free); | |
61a58c6c | 154 | pid_ns->last_pid = pid; |
1da177e4 LT |
155 | return pid; |
156 | } | |
157 | offset = find_next_offset(map, offset); | |
61a58c6c | 158 | pid = mk_pid(pid_ns, map, offset); |
1da177e4 LT |
159 | /* |
160 | * find_next_offset() found a bit, the pid from it | |
161 | * is in-bounds, and if we fell back to the last | |
162 | * bitmap block and the final block was the same | |
163 | * as the starting point, pid is before last_pid. | |
164 | */ | |
165 | } while (offset < BITS_PER_PAGE && pid < pid_max && | |
166 | (i != max_scan || pid < last || | |
167 | !((last+1) & BITS_PER_PAGE_MASK))); | |
168 | } | |
61a58c6c | 169 | if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { |
1da177e4 LT |
170 | ++map; |
171 | offset = 0; | |
172 | } else { | |
61a58c6c | 173 | map = &pid_ns->pidmap[0]; |
1da177e4 LT |
174 | offset = RESERVED_PIDS; |
175 | if (unlikely(last == offset)) | |
176 | break; | |
177 | } | |
61a58c6c | 178 | pid = mk_pid(pid_ns, map, offset); |
1da177e4 LT |
179 | } |
180 | return -1; | |
181 | } | |
182 | ||
74bd59bb | 183 | int next_pidmap(struct pid_namespace *pid_ns, int last) |
0804ef4b EB |
184 | { |
185 | int offset; | |
f40f50d3 | 186 | struct pidmap *map, *end; |
0804ef4b EB |
187 | |
188 | offset = (last + 1) & BITS_PER_PAGE_MASK; | |
61a58c6c SB |
189 | map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE]; |
190 | end = &pid_ns->pidmap[PIDMAP_ENTRIES]; | |
f40f50d3 | 191 | for (; map < end; map++, offset = 0) { |
0804ef4b EB |
192 | if (unlikely(!map->page)) |
193 | continue; | |
194 | offset = find_next_bit((map)->page, BITS_PER_PAGE, offset); | |
195 | if (offset < BITS_PER_PAGE) | |
61a58c6c | 196 | return mk_pid(pid_ns, map, offset); |
0804ef4b EB |
197 | } |
198 | return -1; | |
199 | } | |
200 | ||
7ad5b3a5 | 201 | void put_pid(struct pid *pid) |
92476d7f | 202 | { |
baf8f0f8 PE |
203 | struct pid_namespace *ns; |
204 | ||
92476d7f EB |
205 | if (!pid) |
206 | return; | |
baf8f0f8 | 207 | |
8ef047aa | 208 | ns = pid->numbers[pid->level].ns; |
92476d7f | 209 | if ((atomic_read(&pid->count) == 1) || |
8ef047aa | 210 | atomic_dec_and_test(&pid->count)) { |
baf8f0f8 | 211 | kmem_cache_free(ns->pid_cachep, pid); |
b461cc03 | 212 | put_pid_ns(ns); |
8ef047aa | 213 | } |
92476d7f | 214 | } |
bbf73147 | 215 | EXPORT_SYMBOL_GPL(put_pid); |
92476d7f EB |
216 | |
217 | static void delayed_put_pid(struct rcu_head *rhp) | |
218 | { | |
219 | struct pid *pid = container_of(rhp, struct pid, rcu); | |
220 | put_pid(pid); | |
221 | } | |
222 | ||
7ad5b3a5 | 223 | void free_pid(struct pid *pid) |
92476d7f EB |
224 | { |
225 | /* We can be called with write_lock_irq(&tasklist_lock) held */ | |
8ef047aa | 226 | int i; |
92476d7f EB |
227 | unsigned long flags; |
228 | ||
229 | spin_lock_irqsave(&pidmap_lock, flags); | |
198fe21b PE |
230 | for (i = 0; i <= pid->level; i++) |
231 | hlist_del_rcu(&pid->numbers[i].pid_chain); | |
92476d7f EB |
232 | spin_unlock_irqrestore(&pidmap_lock, flags); |
233 | ||
8ef047aa PE |
234 | for (i = 0; i <= pid->level; i++) |
235 | free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr); | |
236 | ||
92476d7f EB |
237 | call_rcu(&pid->rcu, delayed_put_pid); |
238 | } | |
239 | ||
8ef047aa | 240 | struct pid *alloc_pid(struct pid_namespace *ns) |
92476d7f EB |
241 | { |
242 | struct pid *pid; | |
243 | enum pid_type type; | |
8ef047aa PE |
244 | int i, nr; |
245 | struct pid_namespace *tmp; | |
198fe21b | 246 | struct upid *upid; |
92476d7f | 247 | |
baf8f0f8 | 248 | pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); |
92476d7f EB |
249 | if (!pid) |
250 | goto out; | |
251 | ||
8ef047aa PE |
252 | tmp = ns; |
253 | for (i = ns->level; i >= 0; i--) { | |
254 | nr = alloc_pidmap(tmp); | |
255 | if (nr < 0) | |
256 | goto out_free; | |
92476d7f | 257 | |
8ef047aa PE |
258 | pid->numbers[i].nr = nr; |
259 | pid->numbers[i].ns = tmp; | |
260 | tmp = tmp->parent; | |
261 | } | |
262 | ||
b461cc03 | 263 | get_pid_ns(ns); |
8ef047aa | 264 | pid->level = ns->level; |
92476d7f | 265 | atomic_set(&pid->count, 1); |
92476d7f EB |
266 | for (type = 0; type < PIDTYPE_MAX; ++type) |
267 | INIT_HLIST_HEAD(&pid->tasks[type]); | |
268 | ||
269 | spin_lock_irq(&pidmap_lock); | |
198fe21b PE |
270 | for (i = ns->level; i >= 0; i--) { |
271 | upid = &pid->numbers[i]; | |
272 | hlist_add_head_rcu(&upid->pid_chain, | |
273 | &pid_hash[pid_hashfn(upid->nr, upid->ns)]); | |
274 | } | |
92476d7f EB |
275 | spin_unlock_irq(&pidmap_lock); |
276 | ||
277 | out: | |
278 | return pid; | |
279 | ||
280 | out_free: | |
8ef047aa PE |
281 | for (i++; i <= ns->level; i++) |
282 | free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr); | |
283 | ||
baf8f0f8 | 284 | kmem_cache_free(ns->pid_cachep, pid); |
92476d7f EB |
285 | pid = NULL; |
286 | goto out; | |
287 | } | |
288 | ||
7ad5b3a5 | 289 | struct pid *find_pid_ns(int nr, struct pid_namespace *ns) |
1da177e4 LT |
290 | { |
291 | struct hlist_node *elem; | |
198fe21b PE |
292 | struct upid *pnr; |
293 | ||
294 | hlist_for_each_entry_rcu(pnr, elem, | |
295 | &pid_hash[pid_hashfn(nr, ns)], pid_chain) | |
296 | if (pnr->nr == nr && pnr->ns == ns) | |
297 | return container_of(pnr, struct pid, | |
298 | numbers[ns->level]); | |
1da177e4 | 299 | |
1da177e4 LT |
300 | return NULL; |
301 | } | |
198fe21b | 302 | EXPORT_SYMBOL_GPL(find_pid_ns); |
1da177e4 | 303 | |
8990571e PE |
304 | struct pid *find_vpid(int nr) |
305 | { | |
306 | return find_pid_ns(nr, current->nsproxy->pid_ns); | |
307 | } | |
308 | EXPORT_SYMBOL_GPL(find_vpid); | |
309 | ||
310 | struct pid *find_pid(int nr) | |
311 | { | |
312 | return find_pid_ns(nr, &init_pid_ns); | |
313 | } | |
314 | EXPORT_SYMBOL_GPL(find_pid); | |
315 | ||
e713d0da SB |
316 | /* |
317 | * attach_pid() must be called with the tasklist_lock write-held. | |
318 | */ | |
7ad5b3a5 | 319 | int attach_pid(struct task_struct *task, enum pid_type type, |
e713d0da | 320 | struct pid *pid) |
1da177e4 | 321 | { |
92476d7f | 322 | struct pid_link *link; |
92476d7f | 323 | |
92476d7f | 324 | link = &task->pids[type]; |
e713d0da | 325 | link->pid = pid; |
92476d7f | 326 | hlist_add_head_rcu(&link->node, &pid->tasks[type]); |
1da177e4 LT |
327 | |
328 | return 0; | |
329 | } | |
330 | ||
7ad5b3a5 | 331 | void detach_pid(struct task_struct *task, enum pid_type type) |
1da177e4 | 332 | { |
92476d7f EB |
333 | struct pid_link *link; |
334 | struct pid *pid; | |
335 | int tmp; | |
1da177e4 | 336 | |
92476d7f EB |
337 | link = &task->pids[type]; |
338 | pid = link->pid; | |
1da177e4 | 339 | |
92476d7f EB |
340 | hlist_del_rcu(&link->node); |
341 | link->pid = NULL; | |
1da177e4 | 342 | |
92476d7f EB |
343 | for (tmp = PIDTYPE_MAX; --tmp >= 0; ) |
344 | if (!hlist_empty(&pid->tasks[tmp])) | |
345 | return; | |
1da177e4 | 346 | |
92476d7f | 347 | free_pid(pid); |
1da177e4 LT |
348 | } |
349 | ||
c18258c6 | 350 | /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ |
7ad5b3a5 | 351 | void transfer_pid(struct task_struct *old, struct task_struct *new, |
c18258c6 EB |
352 | enum pid_type type) |
353 | { | |
354 | new->pids[type].pid = old->pids[type].pid; | |
355 | hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node); | |
356 | old->pids[type].pid = NULL; | |
357 | } | |
358 | ||
7ad5b3a5 | 359 | struct task_struct *pid_task(struct pid *pid, enum pid_type type) |
1da177e4 | 360 | { |
92476d7f EB |
361 | struct task_struct *result = NULL; |
362 | if (pid) { | |
363 | struct hlist_node *first; | |
364 | first = rcu_dereference(pid->tasks[type].first); | |
365 | if (first) | |
366 | result = hlist_entry(first, struct task_struct, pids[(type)].node); | |
367 | } | |
368 | return result; | |
369 | } | |
eccba068 | 370 | EXPORT_SYMBOL(pid_task); |
1da177e4 | 371 | |
92476d7f EB |
372 | /* |
373 | * Must be called under rcu_read_lock() or with tasklist_lock read-held. | |
374 | */ | |
198fe21b PE |
375 | struct task_struct *find_task_by_pid_type_ns(int type, int nr, |
376 | struct pid_namespace *ns) | |
92476d7f | 377 | { |
198fe21b | 378 | return pid_task(find_pid_ns(nr, ns), type); |
92476d7f | 379 | } |
1da177e4 | 380 | |
198fe21b | 381 | EXPORT_SYMBOL(find_task_by_pid_type_ns); |
1da177e4 | 382 | |
228ebcbe PE |
383 | struct task_struct *find_task_by_pid(pid_t nr) |
384 | { | |
385 | return find_task_by_pid_type_ns(PIDTYPE_PID, nr, &init_pid_ns); | |
386 | } | |
387 | EXPORT_SYMBOL(find_task_by_pid); | |
388 | ||
389 | struct task_struct *find_task_by_vpid(pid_t vnr) | |
390 | { | |
391 | return find_task_by_pid_type_ns(PIDTYPE_PID, vnr, | |
392 | current->nsproxy->pid_ns); | |
393 | } | |
394 | EXPORT_SYMBOL(find_task_by_vpid); | |
395 | ||
396 | struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns) | |
397 | { | |
398 | return find_task_by_pid_type_ns(PIDTYPE_PID, nr, ns); | |
399 | } | |
400 | EXPORT_SYMBOL(find_task_by_pid_ns); | |
401 | ||
1a657f78 ON |
402 | struct pid *get_task_pid(struct task_struct *task, enum pid_type type) |
403 | { | |
404 | struct pid *pid; | |
405 | rcu_read_lock(); | |
406 | pid = get_pid(task->pids[type].pid); | |
407 | rcu_read_unlock(); | |
408 | return pid; | |
409 | } | |
410 | ||
7ad5b3a5 | 411 | struct task_struct *get_pid_task(struct pid *pid, enum pid_type type) |
92476d7f EB |
412 | { |
413 | struct task_struct *result; | |
414 | rcu_read_lock(); | |
415 | result = pid_task(pid, type); | |
416 | if (result) | |
417 | get_task_struct(result); | |
418 | rcu_read_unlock(); | |
419 | return result; | |
1da177e4 LT |
420 | } |
421 | ||
92476d7f | 422 | struct pid *find_get_pid(pid_t nr) |
1da177e4 LT |
423 | { |
424 | struct pid *pid; | |
425 | ||
92476d7f | 426 | rcu_read_lock(); |
198fe21b | 427 | pid = get_pid(find_vpid(nr)); |
92476d7f | 428 | rcu_read_unlock(); |
1da177e4 | 429 | |
92476d7f | 430 | return pid; |
1da177e4 LT |
431 | } |
432 | ||
7af57294 PE |
433 | pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) |
434 | { | |
435 | struct upid *upid; | |
436 | pid_t nr = 0; | |
437 | ||
438 | if (pid && ns->level <= pid->level) { | |
439 | upid = &pid->numbers[ns->level]; | |
440 | if (upid->ns == ns) | |
441 | nr = upid->nr; | |
442 | } | |
443 | return nr; | |
444 | } | |
445 | ||
44c4e1b2 EB |
446 | pid_t pid_vnr(struct pid *pid) |
447 | { | |
448 | return pid_nr_ns(pid, current->nsproxy->pid_ns); | |
449 | } | |
450 | EXPORT_SYMBOL_GPL(pid_vnr); | |
451 | ||
2f2a3a46 PE |
452 | pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) |
453 | { | |
454 | return pid_nr_ns(task_pid(tsk), ns); | |
455 | } | |
456 | EXPORT_SYMBOL(task_pid_nr_ns); | |
457 | ||
458 | pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) | |
459 | { | |
460 | return pid_nr_ns(task_tgid(tsk), ns); | |
461 | } | |
462 | EXPORT_SYMBOL(task_tgid_nr_ns); | |
463 | ||
464 | pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) | |
465 | { | |
466 | return pid_nr_ns(task_pgrp(tsk), ns); | |
467 | } | |
468 | EXPORT_SYMBOL(task_pgrp_nr_ns); | |
469 | ||
470 | pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) | |
471 | { | |
472 | return pid_nr_ns(task_session(tsk), ns); | |
473 | } | |
474 | EXPORT_SYMBOL(task_session_nr_ns); | |
475 | ||
0804ef4b EB |
476 | /* |
477 | * Used by proc to find the first pid that is greater then or equal to nr. | |
478 | * | |
479 | * If there is a pid at nr this function is exactly the same as find_pid. | |
480 | */ | |
198fe21b | 481 | struct pid *find_ge_pid(int nr, struct pid_namespace *ns) |
0804ef4b EB |
482 | { |
483 | struct pid *pid; | |
484 | ||
485 | do { | |
198fe21b | 486 | pid = find_pid_ns(nr, ns); |
0804ef4b EB |
487 | if (pid) |
488 | break; | |
198fe21b | 489 | nr = next_pidmap(ns, nr); |
0804ef4b EB |
490 | } while (nr > 0); |
491 | ||
492 | return pid; | |
493 | } | |
bbf73147 | 494 | EXPORT_SYMBOL_GPL(find_get_pid); |
0804ef4b | 495 | |
1da177e4 LT |
496 | /* |
497 | * The pid hash table is scaled according to the amount of memory in the | |
498 | * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or | |
499 | * more. | |
500 | */ | |
501 | void __init pidhash_init(void) | |
502 | { | |
92476d7f | 503 | int i, pidhash_size; |
1da177e4 LT |
504 | unsigned long megabytes = nr_kernel_pages >> (20 - PAGE_SHIFT); |
505 | ||
506 | pidhash_shift = max(4, fls(megabytes * 4)); | |
507 | pidhash_shift = min(12, pidhash_shift); | |
508 | pidhash_size = 1 << pidhash_shift; | |
509 | ||
510 | printk("PID hash table entries: %d (order: %d, %Zd bytes)\n", | |
511 | pidhash_size, pidhash_shift, | |
92476d7f EB |
512 | pidhash_size * sizeof(struct hlist_head)); |
513 | ||
514 | pid_hash = alloc_bootmem(pidhash_size * sizeof(*(pid_hash))); | |
515 | if (!pid_hash) | |
516 | panic("Could not alloc pidhash!\n"); | |
517 | for (i = 0; i < pidhash_size; i++) | |
518 | INIT_HLIST_HEAD(&pid_hash[i]); | |
1da177e4 LT |
519 | } |
520 | ||
521 | void __init pidmap_init(void) | |
522 | { | |
61a58c6c | 523 | init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
73b9ebfe | 524 | /* Reserve PID 0. We never call free_pidmap(0) */ |
61a58c6c SB |
525 | set_bit(0, init_pid_ns.pidmap[0].page); |
526 | atomic_dec(&init_pid_ns.pidmap[0].nr_free); | |
92476d7f | 527 | |
74bd59bb PE |
528 | init_pid_ns.pid_cachep = KMEM_CACHE(pid, |
529 | SLAB_HWCACHE_ALIGN | SLAB_PANIC); | |
1da177e4 | 530 | } |