blob: 064e76afa507a252f6f4de8aec046f03c6cc62a7 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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).
Pavel Emelyanov30e49c22007-10-18 23:40:10 -070021 *
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 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 */
28
29#include <linux/mm.h>
30#include <linux/module.h>
31#include <linux/slab.h>
32#include <linux/init.h>
Franck Bui-Huu82524742008-05-12 21:21:05 +020033#include <linux/rculist.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/bootmem.h>
35#include <linux/hash.h>
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -080036#include <linux/pid_namespace.h>
Sukadev Bhattiprolu820e45d2007-05-10 22:23:00 -070037#include <linux/init_task.h>
Sukadev Bhattiprolu3eb07c82007-10-18 23:40:13 -070038#include <linux/syscalls.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -070040#define pid_hashfn(nr, ns) \
41 hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
Eric W. Biederman92476d72006-03-31 02:31:42 -080042static struct hlist_head *pid_hash;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043static int pidhash_shift;
Sukadev Bhattiprolu820e45d2007-05-10 22:23:00 -070044struct pid init_struct_pid = INIT_STRUCT_PID;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46int pid_max = PID_MAX_DEFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48#define RESERVED_PIDS 300
49
50int pid_max_min = RESERVED_PIDS + 1;
51int pid_max_max = PID_MAX_LIMIT;
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#define BITS_PER_PAGE (PAGE_SIZE*8)
54#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070055
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -080056static inline int mk_pid(struct pid_namespace *pid_ns,
57 struct pidmap *map, int off)
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070058{
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -080059 return (map - pid_ns->pidmap)*BITS_PER_PAGE + off;
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070060}
61
Linus Torvalds1da177e2005-04-16 15:20:36 -070062#define find_next_offset(map, off) \
63 find_next_zero_bit((map)->page, BITS_PER_PAGE, off)
64
65/*
66 * PID-map pages start out as NULL, they get allocated upon
67 * first use and are never deallocated. This way a low pid_max
68 * value does not cause lots of bitmaps to be allocated, but
69 * the scheme scales to up to 4 million PIDs, runtime.
70 */
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -080071struct pid_namespace init_pid_ns = {
Cedric Le Goater9a575a92006-12-08 02:37:59 -080072 .kref = {
73 .refcount = ATOMIC_INIT(2),
74 },
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070075 .pidmap = {
76 [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
77 },
Sukadev Bhattiprolu84d73782006-12-08 02:38:01 -080078 .last_pid = 0,
Pavel Emelyanovfaacbfd2007-10-18 23:40:04 -070079 .level = 0,
80 .child_reaper = &init_task,
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070081};
Pavel Emelyanov198fe212007-10-18 23:40:06 -070082EXPORT_SYMBOL_GPL(init_pid_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
Pavel Emelyanovb461cc02007-10-18 23:40:09 -070084int is_container_init(struct task_struct *tsk)
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070085{
Pavel Emelyanovb461cc02007-10-18 23:40:09 -070086 int ret = 0;
87 struct pid *pid;
88
89 rcu_read_lock();
90 pid = task_pid(tsk);
91 if (pid != NULL && pid->numbers[pid->level].nr == 1)
92 ret = 1;
93 rcu_read_unlock();
94
95 return ret;
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070096}
Pavel Emelyanovb461cc02007-10-18 23:40:09 -070097EXPORT_SYMBOL(is_container_init);
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070098
Eric W. Biederman92476d72006-03-31 02:31:42 -080099/*
100 * Note: disable interrupts while the pidmap_lock is held as an
101 * interrupt might come in and do read_lock(&tasklist_lock).
102 *
103 * If we don't disable interrupts there is a nasty deadlock between
104 * detach_pid()->free_pid() and another cpu that does
105 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
106 * read_lock(&tasklist_lock);
107 *
108 * After we clean up the tasklist_lock and know there are no
109 * irq handlers that take it we can leave the interrupts enabled.
110 * For now it is easier to be safe than to prove it can't happen.
111 */
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -0700112
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
114
Oleg Nesterovb7127aa2008-04-30 00:54:22 -0700115static void free_pidmap(struct upid *upid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116{
Oleg Nesterovb7127aa2008-04-30 00:54:22 -0700117 int nr = upid->nr;
118 struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE;
119 int offset = nr & BITS_PER_PAGE_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121 clear_bit(offset, map->page);
122 atomic_inc(&map->nr_free);
123}
124
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800125static int alloc_pidmap(struct pid_namespace *pid_ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126{
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800127 int i, offset, max_scan, pid, last = pid_ns->last_pid;
Sukadev Bhattiprolu6a1f3b82006-10-02 02:17:20 -0700128 struct pidmap *map;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
130 pid = last + 1;
131 if (pid >= pid_max)
132 pid = RESERVED_PIDS;
133 offset = pid & BITS_PER_PAGE_MASK;
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800134 map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
136 for (i = 0; i <= max_scan; ++i) {
137 if (unlikely(!map->page)) {
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -0700138 void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 /*
140 * Free the page if someone raced with us
141 * installing it:
142 */
Eric W. Biederman92476d72006-03-31 02:31:42 -0800143 spin_lock_irq(&pidmap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 if (map->page)
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -0700145 kfree(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 else
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -0700147 map->page = page;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800148 spin_unlock_irq(&pidmap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 if (unlikely(!map->page))
150 break;
151 }
152 if (likely(atomic_read(&map->nr_free))) {
153 do {
154 if (!test_and_set_bit(offset, map->page)) {
155 atomic_dec(&map->nr_free);
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800156 pid_ns->last_pid = pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 return pid;
158 }
159 offset = find_next_offset(map, offset);
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800160 pid = mk_pid(pid_ns, map, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 /*
162 * find_next_offset() found a bit, the pid from it
163 * is in-bounds, and if we fell back to the last
164 * bitmap block and the final block was the same
165 * as the starting point, pid is before last_pid.
166 */
167 } while (offset < BITS_PER_PAGE && pid < pid_max &&
168 (i != max_scan || pid < last ||
169 !((last+1) & BITS_PER_PAGE_MASK)));
170 }
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800171 if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 ++map;
173 offset = 0;
174 } else {
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800175 map = &pid_ns->pidmap[0];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 offset = RESERVED_PIDS;
177 if (unlikely(last == offset))
178 break;
179 }
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800180 pid = mk_pid(pid_ns, map, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 }
182 return -1;
183}
184
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800185int next_pidmap(struct pid_namespace *pid_ns, int last)
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700186{
187 int offset;
Eric W. Biedermanf40f50d2006-10-02 02:17:25 -0700188 struct pidmap *map, *end;
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700189
190 offset = (last + 1) & BITS_PER_PAGE_MASK;
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800191 map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
192 end = &pid_ns->pidmap[PIDMAP_ENTRIES];
Eric W. Biedermanf40f50d2006-10-02 02:17:25 -0700193 for (; map < end; map++, offset = 0) {
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700194 if (unlikely(!map->page))
195 continue;
196 offset = find_next_bit((map)->page, BITS_PER_PAGE, offset);
197 if (offset < BITS_PER_PAGE)
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800198 return mk_pid(pid_ns, map, offset);
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700199 }
200 return -1;
201}
202
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800203void put_pid(struct pid *pid)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800204{
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700205 struct pid_namespace *ns;
206
Eric W. Biederman92476d72006-03-31 02:31:42 -0800207 if (!pid)
208 return;
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700209
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700210 ns = pid->numbers[pid->level].ns;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800211 if ((atomic_read(&pid->count) == 1) ||
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700212 atomic_dec_and_test(&pid->count)) {
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700213 kmem_cache_free(ns->pid_cachep, pid);
Pavel Emelyanovb461cc02007-10-18 23:40:09 -0700214 put_pid_ns(ns);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700215 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800216}
Eric W. Biedermanbbf73142006-10-02 02:17:11 -0700217EXPORT_SYMBOL_GPL(put_pid);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800218
219static void delayed_put_pid(struct rcu_head *rhp)
220{
221 struct pid *pid = container_of(rhp, struct pid, rcu);
222 put_pid(pid);
223}
224
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800225void free_pid(struct pid *pid)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800226{
227 /* We can be called with write_lock_irq(&tasklist_lock) held */
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700228 int i;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800229 unsigned long flags;
230
231 spin_lock_irqsave(&pidmap_lock, flags);
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700232 for (i = 0; i <= pid->level; i++)
233 hlist_del_rcu(&pid->numbers[i].pid_chain);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800234 spin_unlock_irqrestore(&pidmap_lock, flags);
235
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700236 for (i = 0; i <= pid->level; i++)
Oleg Nesterovb7127aa2008-04-30 00:54:22 -0700237 free_pidmap(pid->numbers + i);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700238
Eric W. Biederman92476d72006-03-31 02:31:42 -0800239 call_rcu(&pid->rcu, delayed_put_pid);
240}
241
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700242struct pid *alloc_pid(struct pid_namespace *ns)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800243{
244 struct pid *pid;
245 enum pid_type type;
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700246 int i, nr;
247 struct pid_namespace *tmp;
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700248 struct upid *upid;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800249
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700250 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800251 if (!pid)
252 goto out;
253
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700254 tmp = ns;
255 for (i = ns->level; i >= 0; i--) {
256 nr = alloc_pidmap(tmp);
257 if (nr < 0)
258 goto out_free;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800259
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700260 pid->numbers[i].nr = nr;
261 pid->numbers[i].ns = tmp;
262 tmp = tmp->parent;
263 }
264
Pavel Emelyanovb461cc02007-10-18 23:40:09 -0700265 get_pid_ns(ns);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700266 pid->level = ns->level;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800267 atomic_set(&pid->count, 1);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800268 for (type = 0; type < PIDTYPE_MAX; ++type)
269 INIT_HLIST_HEAD(&pid->tasks[type]);
270
271 spin_lock_irq(&pidmap_lock);
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700272 for (i = ns->level; i >= 0; i--) {
273 upid = &pid->numbers[i];
274 hlist_add_head_rcu(&upid->pid_chain,
275 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
276 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800277 spin_unlock_irq(&pidmap_lock);
278
279out:
280 return pid;
281
282out_free:
Oleg Nesterovb7127aa2008-04-30 00:54:22 -0700283 while (++i <= ns->level)
284 free_pidmap(pid->numbers + i);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700285
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700286 kmem_cache_free(ns->pid_cachep, pid);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800287 pid = NULL;
288 goto out;
289}
290
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800291struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292{
293 struct hlist_node *elem;
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700294 struct upid *pnr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700296 hlist_for_each_entry_rcu(pnr, elem,
297 &pid_hash[pid_hashfn(nr, ns)], pid_chain)
298 if (pnr->nr == nr && pnr->ns == ns)
299 return container_of(pnr, struct pid,
300 numbers[ns->level]);
301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 return NULL;
303}
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700304EXPORT_SYMBOL_GPL(find_pid_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Pavel Emelyanov89905712007-10-18 23:40:19 -0700306struct pid *find_vpid(int nr)
307{
308 return find_pid_ns(nr, current->nsproxy->pid_ns);
309}
310EXPORT_SYMBOL_GPL(find_vpid);
311
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700312/*
313 * attach_pid() must be called with the tasklist_lock write-held.
314 */
Oleg Nesterov24336ea2008-04-30 00:54:26 -0700315void attach_pid(struct task_struct *task, enum pid_type type,
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700316 struct pid *pid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317{
Eric W. Biederman92476d72006-03-31 02:31:42 -0800318 struct pid_link *link;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319
Eric W. Biederman92476d72006-03-31 02:31:42 -0800320 link = &task->pids[type];
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700321 link->pid = pid;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800322 hlist_add_head_rcu(&link->node, &pid->tasks[type]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323}
324
Oleg Nesterov24336ea2008-04-30 00:54:26 -0700325static void __change_pid(struct task_struct *task, enum pid_type type,
326 struct pid *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327{
Eric W. Biederman92476d72006-03-31 02:31:42 -0800328 struct pid_link *link;
329 struct pid *pid;
330 int tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
Eric W. Biederman92476d72006-03-31 02:31:42 -0800332 link = &task->pids[type];
333 pid = link->pid;
334
335 hlist_del_rcu(&link->node);
Oleg Nesterov24336ea2008-04-30 00:54:26 -0700336 link->pid = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
338 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
Eric W. Biederman92476d72006-03-31 02:31:42 -0800339 if (!hlist_empty(&pid->tasks[tmp]))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 return;
341
Eric W. Biederman92476d72006-03-31 02:31:42 -0800342 free_pid(pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343}
344
Oleg Nesterov24336ea2008-04-30 00:54:26 -0700345void detach_pid(struct task_struct *task, enum pid_type type)
346{
347 __change_pid(task, type, NULL);
348}
349
350void change_pid(struct task_struct *task, enum pid_type type,
351 struct pid *pid)
352{
353 __change_pid(task, type, pid);
354 attach_pid(task, type, pid);
355}
356
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700357/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800358void transfer_pid(struct task_struct *old, struct task_struct *new,
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700359 enum pid_type type)
360{
361 new->pids[type].pid = old->pids[type].pid;
362 hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700363}
364
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800365struct task_struct *pid_task(struct pid *pid, enum pid_type type)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800366{
367 struct task_struct *result = NULL;
368 if (pid) {
369 struct hlist_node *first;
370 first = rcu_dereference(pid->tasks[type].first);
371 if (first)
372 result = hlist_entry(first, struct task_struct, pids[(type)].node);
373 }
374 return result;
375}
Pavel Emelyanoveccba062008-02-07 00:13:21 -0800376EXPORT_SYMBOL(pid_task);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800377
378/*
379 * Must be called under rcu_read_lock() or with tasklist_lock read-held.
380 */
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700381struct task_struct *find_task_by_pid_type_ns(int type, int nr,
382 struct pid_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383{
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700384 return pid_task(find_pid_ns(nr, ns), type);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385}
386
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700387EXPORT_SYMBOL(find_task_by_pid_type_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700389struct 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}
394EXPORT_SYMBOL(find_task_by_vpid);
395
396struct 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}
400EXPORT_SYMBOL(find_task_by_pid_ns);
401
Oleg Nesterov1a657f782006-10-02 02:18:59 -0700402struct 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
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800411struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800412{
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;
420}
421
422struct pid *find_get_pid(pid_t nr)
423{
424 struct pid *pid;
425
426 rcu_read_lock();
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700427 pid = get_pid(find_vpid(nr));
Eric W. Biederman92476d72006-03-31 02:31:42 -0800428 rcu_read_unlock();
429
430 return pid;
431}
David Sterba339caf22008-07-25 01:48:31 -0700432EXPORT_SYMBOL_GPL(find_get_pid);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800433
Pavel Emelyanov7af57292007-10-18 23:40:06 -0700434pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
435{
436 struct upid *upid;
437 pid_t nr = 0;
438
439 if (pid && ns->level <= pid->level) {
440 upid = &pid->numbers[ns->level];
441 if (upid->ns == ns)
442 nr = upid->nr;
443 }
444 return nr;
445}
446
Eric W. Biederman44c4e1b2008-02-08 04:19:15 -0800447pid_t pid_vnr(struct pid *pid)
448{
449 return pid_nr_ns(pid, current->nsproxy->pid_ns);
450}
451EXPORT_SYMBOL_GPL(pid_vnr);
452
Pavel Emelyanov2f2a3a42007-10-18 23:40:19 -0700453pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
454{
455 return pid_nr_ns(task_pid(tsk), ns);
456}
457EXPORT_SYMBOL(task_pid_nr_ns);
458
459pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
460{
461 return pid_nr_ns(task_tgid(tsk), ns);
462}
463EXPORT_SYMBOL(task_tgid_nr_ns);
464
465pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
466{
467 return pid_nr_ns(task_pgrp(tsk), ns);
468}
469EXPORT_SYMBOL(task_pgrp_nr_ns);
470
471pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
472{
473 return pid_nr_ns(task_session(tsk), ns);
474}
475EXPORT_SYMBOL(task_session_nr_ns);
476
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477/*
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700478 * Used by proc to find the first pid that is greater then or equal to nr.
479 *
Pavel Emelyanove49859e2008-07-25 01:48:36 -0700480 * If there is a pid at nr this function is exactly the same as find_pid_ns.
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700481 */
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700482struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700483{
484 struct pid *pid;
485
486 do {
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700487 pid = find_pid_ns(nr, ns);
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700488 if (pid)
489 break;
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700490 nr = next_pidmap(ns, nr);
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700491 } while (nr > 0);
492
493 return pid;
494}
495
496/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 * 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 */
501void __init pidhash_init(void)
502{
Eric W. Biederman92476d72006-03-31 02:31:42 -0800503 int i, pidhash_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 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,
Eric W. Biederman92476d72006-03-31 02:31:42 -0800512 pidhash_size * sizeof(struct hlist_head));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
Eric W. Biederman92476d72006-03-31 02:31:42 -0800514 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]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519}
520
521void __init pidmap_init(void)
522{
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800523 init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
Oleg Nesterov73b9ebf2006-03-28 16:11:07 -0800524 /* Reserve PID 0. We never call free_pidmap(0) */
Sukadev Bhattiprolu61a58c62006-12-08 02:37:58 -0800525 set_bit(0, init_pid_ns.pidmap[0].page);
526 atomic_dec(&init_pid_ns.pidmap[0].nr_free);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800527
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800528 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
529 SLAB_HWCACHE_ALIGN | SLAB_PANIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530}