blob: 157fe4b199713b65cb62c6d591225306cd5289f9 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Generic pidhash and scalable, time-bounded PID allocator
3 *
Nadia Yvette Chambers6d49e352012-12-06 10:39:54 +01004 * (C) 2002-2003 Nadia Yvette Chambers, IBM
5 * (C) 2004 Nadia Yvette Chambers, Oracle
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 * (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>
Paul Gortmaker9984de12011-05-23 14:51:41 -040030#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#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>
David Howells0bb80f22013-04-12 01:50:06 +010039#include <linux/proc_ns.h>
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -070040#include <linux/proc_fs.h>
Ingo Molnar29930022017-02-08 18:51:36 +010041#include <linux/sched/task.h>
Gargi Sharma95846ec2017-11-17 15:30:30 -080042#include <linux/idr.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
David Howellse1e871a2018-01-02 15:12:01 +000044struct pid init_struct_pid = {
45 .count = ATOMIC_INIT(1),
46 .tasks = {
47 { .first = NULL },
48 { .first = NULL },
49 { .first = NULL },
50 },
51 .level = 0,
52 .numbers = { {
53 .nr = 0,
54 .ns = &init_pid_ns,
55 }, }
56};
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
58int pid_max = PID_MAX_DEFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60#define RESERVED_PIDS 300
61
62int pid_max_min = RESERVED_PIDS + 1;
63int pid_max_max = PID_MAX_LIMIT;
64
Linus Torvalds1da177e2005-04-16 15:20:36 -070065/*
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 = {
Peter Zijlstra1e24edc2016-11-14 17:12:23 +010072 .kref = KREF_INIT(2),
Matthew Wilcoxf6bb2a22018-04-10 16:36:52 -070073 .idr = IDR_INIT(init_pid_ns.idr),
Gargi Sharmae8cfbc22017-11-17 15:30:34 -080074 .pid_allocated = PIDNS_ADDING,
Pavel Emelyanovfaacbfd2007-10-18 23:40:04 -070075 .level = 0,
76 .child_reaper = &init_task,
Eric W. Biederman49f4d8b2012-08-02 04:25:10 -070077 .user_ns = &init_user_ns,
Al Viro435d5f42014-10-31 22:56:04 -040078 .ns.inum = PROC_PID_INIT_INO,
Al Viro33c42942014-11-01 02:32:53 -040079#ifdef CONFIG_PID_NS
80 .ns.ops = &pidns_operations,
81#endif
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070082};
Pavel Emelyanov198fe212007-10-18 23:40:06 -070083EXPORT_SYMBOL_GPL(init_pid_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Eric W. Biederman92476d72006-03-31 02:31:42 -080085/*
86 * Note: disable interrupts while the pidmap_lock is held as an
87 * interrupt might come in and do read_lock(&tasklist_lock).
88 *
89 * If we don't disable interrupts there is a nasty deadlock between
90 * detach_pid()->free_pid() and another cpu that does
91 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
92 * read_lock(&tasklist_lock);
93 *
94 * After we clean up the tasklist_lock and know there are no
95 * irq handlers that take it we can leave the interrupts enabled.
96 * For now it is easier to be safe than to prove it can't happen.
97 */
Sukadev Bhattiprolu3fbc9642006-10-02 02:17:24 -070098
Linus Torvalds1da177e2005-04-16 15:20:36 -070099static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);
100
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800101void put_pid(struct pid *pid)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800102{
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700103 struct pid_namespace *ns;
104
Eric W. Biederman92476d72006-03-31 02:31:42 -0800105 if (!pid)
106 return;
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700107
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700108 ns = pid->numbers[pid->level].ns;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800109 if ((atomic_read(&pid->count) == 1) ||
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700110 atomic_dec_and_test(&pid->count)) {
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700111 kmem_cache_free(ns->pid_cachep, pid);
Pavel Emelyanovb461cc02007-10-18 23:40:09 -0700112 put_pid_ns(ns);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700113 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800114}
Eric W. Biedermanbbf73142006-10-02 02:17:11 -0700115EXPORT_SYMBOL_GPL(put_pid);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800116
117static void delayed_put_pid(struct rcu_head *rhp)
118{
119 struct pid *pid = container_of(rhp, struct pid, rcu);
120 put_pid(pid);
121}
122
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800123void free_pid(struct pid *pid)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800124{
125 /* We can be called with write_lock_irq(&tasklist_lock) held */
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700126 int i;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800127 unsigned long flags;
128
129 spin_lock_irqsave(&pidmap_lock, flags);
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700130 for (i = 0; i <= pid->level; i++) {
131 struct upid *upid = pid->numbers + i;
Eric W. Biedermanaf4b8a82012-08-01 15:03:42 -0700132 struct pid_namespace *ns = upid->ns;
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800133 switch (--ns->pid_allocated) {
Eric W. Biedermana6064882013-08-29 13:56:50 -0700134 case 2:
Eric W. Biedermanaf4b8a82012-08-01 15:03:42 -0700135 case 1:
136 /* When all that is left in the pid namespace
137 * is the reaper wake up the reaper. The reaper
138 * may be sleeping in zap_pid_ns_processes().
139 */
140 wake_up_process(ns->child_reaper);
141 break;
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800142 case PIDNS_ADDING:
Oleg Nesterov314a8ad2013-09-30 13:45:27 -0700143 /* Handle a fork failure of the first process */
144 WARN_ON(ns->child_reaper);
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800145 ns->pid_allocated = 0;
Oleg Nesterov314a8ad2013-09-30 13:45:27 -0700146 /* fall through */
Eric W. Biedermanaf4b8a82012-08-01 15:03:42 -0700147 case 0:
Eric W. Biedermanaf4b8a82012-08-01 15:03:42 -0700148 schedule_work(&ns->proc_work);
149 break;
Eric W. Biederman5e1182deb2010-07-12 18:50:25 -0700150 }
Gargi Sharma95846ec2017-11-17 15:30:30 -0800151
152 idr_remove(&ns->idr, upid->nr);
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700153 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800154 spin_unlock_irqrestore(&pidmap_lock, flags);
155
Eric W. Biederman92476d72006-03-31 02:31:42 -0800156 call_rcu(&pid->rcu, delayed_put_pid);
157}
158
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700159struct pid *alloc_pid(struct pid_namespace *ns)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800160{
161 struct pid *pid;
162 enum pid_type type;
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700163 int i, nr;
164 struct pid_namespace *tmp;
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700165 struct upid *upid;
Michal Hocko35f71bc2015-04-16 12:47:38 -0700166 int retval = -ENOMEM;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800167
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700168 pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800169 if (!pid)
Michal Hocko35f71bc2015-04-16 12:47:38 -0700170 return ERR_PTR(retval);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800171
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700172 tmp = ns;
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700173 pid->level = ns->level;
Gargi Sharma95846ec2017-11-17 15:30:30 -0800174
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700175 for (i = ns->level; i >= 0; i--) {
Gargi Sharma95846ec2017-11-17 15:30:30 -0800176 int pid_min = 1;
177
178 idr_preload(GFP_KERNEL);
179 spin_lock_irq(&pidmap_lock);
180
181 /*
182 * init really needs pid 1, but after reaching the maximum
183 * wrap back to RESERVED_PIDS
184 */
185 if (idr_get_cursor(&tmp->idr) > RESERVED_PIDS)
186 pid_min = RESERVED_PIDS;
187
188 /*
189 * Store a null pointer so find_pid_ns does not find
190 * a partially initialized PID (see below).
191 */
192 nr = idr_alloc_cyclic(&tmp->idr, NULL, pid_min,
193 pid_max, GFP_ATOMIC);
194 spin_unlock_irq(&pidmap_lock);
195 idr_preload_end();
196
Arnd Bergmann287980e2016-05-27 23:23:25 +0200197 if (nr < 0) {
Michal Hocko35f71bc2015-04-16 12:47:38 -0700198 retval = nr;
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700199 goto out_free;
Michal Hocko35f71bc2015-04-16 12:47:38 -0700200 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800201
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700202 pid->numbers[i].nr = nr;
203 pid->numbers[i].ns = tmp;
204 tmp = tmp->parent;
205 }
206
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700207 if (unlikely(is_child_reaper(pid))) {
Eric W. Biedermanc0ee5542017-12-22 12:37:43 -0600208 if (pid_ns_prepare_proc(ns))
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700209 goto out_free;
210 }
211
Pavel Emelyanovb461cc02007-10-18 23:40:09 -0700212 get_pid_ns(ns);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800213 atomic_set(&pid->count, 1);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800214 for (type = 0; type < PIDTYPE_MAX; ++type)
215 INIT_HLIST_HEAD(&pid->tasks[type]);
216
André Goddard Rosa417e3152009-12-15 16:47:40 -0800217 upid = pid->numbers + ns->level;
Eric W. Biederman92476d72006-03-31 02:31:42 -0800218 spin_lock_irq(&pidmap_lock);
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800219 if (!(ns->pid_allocated & PIDNS_ADDING))
Eric W. Biederman5e1182deb2010-07-12 18:50:25 -0700220 goto out_unlock;
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700221 for ( ; upid >= pid->numbers; --upid) {
Gargi Sharma95846ec2017-11-17 15:30:30 -0800222 /* Make the PID visible to find_pid_ns. */
223 idr_replace(&upid->ns->idr, pid, upid->nr);
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800224 upid->ns->pid_allocated++;
Eric W. Biederman0a01f2c2012-08-01 10:33:47 -0700225 }
Eric W. Biederman92476d72006-03-31 02:31:42 -0800226 spin_unlock_irq(&pidmap_lock);
227
Eric W. Biederman92476d72006-03-31 02:31:42 -0800228 return pid;
229
Eric W. Biederman5e1182deb2010-07-12 18:50:25 -0700230out_unlock:
Eric W. Biederman6e666882013-02-12 13:46:23 -0800231 spin_unlock_irq(&pidmap_lock);
Oleg Nesterov24c037e2014-12-10 15:55:25 -0800232 put_pid_ns(ns);
233
Eric W. Biederman92476d72006-03-31 02:31:42 -0800234out_free:
Gargi Sharma95846ec2017-11-17 15:30:30 -0800235 spin_lock_irq(&pidmap_lock);
Oleg Nesterovb7127aa2008-04-30 00:54:22 -0700236 while (++i <= ns->level)
Gargi Sharma95846ec2017-11-17 15:30:30 -0800237 idr_remove(&ns->idr, (pid->numbers + i)->nr);
238
Eric W. Biedermanc0ee5542017-12-22 12:37:43 -0600239 /* On failure to allocate the first pid, reset the state */
240 if (ns->pid_allocated == PIDNS_ADDING)
241 idr_set_cursor(&ns->idr, 0);
242
Gargi Sharma95846ec2017-11-17 15:30:30 -0800243 spin_unlock_irq(&pidmap_lock);
Pavel Emelyanov8ef047a2007-10-18 23:40:05 -0700244
Pavel Emelianovbaf8f0f2007-10-18 23:39:48 -0700245 kmem_cache_free(ns->pid_cachep, pid);
Michal Hocko35f71bc2015-04-16 12:47:38 -0700246 return ERR_PTR(retval);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800247}
248
Eric W. Biedermanc876ad762012-12-21 20:27:12 -0800249void disable_pid_allocation(struct pid_namespace *ns)
250{
251 spin_lock_irq(&pidmap_lock);
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800252 ns->pid_allocated &= ~PIDNS_ADDING;
Eric W. Biedermanc876ad762012-12-21 20:27:12 -0800253 spin_unlock_irq(&pidmap_lock);
254}
255
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800256struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800258 return idr_find(&ns->idr, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259}
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700260EXPORT_SYMBOL_GPL(find_pid_ns);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
Pavel Emelyanov89905712007-10-18 23:40:19 -0700262struct pid *find_vpid(int nr)
263{
Eric W. Biederman17cf22c2010-03-02 14:51:53 -0800264 return find_pid_ns(nr, task_active_pid_ns(current));
Pavel Emelyanov89905712007-10-18 23:40:19 -0700265}
266EXPORT_SYMBOL_GPL(find_vpid);
267
Sukadev Bhattiprolue713d0d2007-05-10 22:22:58 -0700268/*
269 * attach_pid() must be called with the tasklist_lock write-held.
270 */
Oleg Nesterov81907732013-07-03 15:08:31 -0700271void attach_pid(struct task_struct *task, enum pid_type type)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272{
Oleg Nesterov81907732013-07-03 15:08:31 -0700273 struct pid_link *link = &task->pids[type];
274 hlist_add_head_rcu(&link->node, &link->pid->tasks[type]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275}
276
Oleg Nesterov24336eae2008-04-30 00:54:26 -0700277static void __change_pid(struct task_struct *task, enum pid_type type,
278 struct pid *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279{
Eric W. Biederman92476d72006-03-31 02:31:42 -0800280 struct pid_link *link;
281 struct pid *pid;
282 int tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283
Eric W. Biederman92476d72006-03-31 02:31:42 -0800284 link = &task->pids[type];
285 pid = link->pid;
286
287 hlist_del_rcu(&link->node);
Oleg Nesterov24336eae2008-04-30 00:54:26 -0700288 link->pid = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289
290 for (tmp = PIDTYPE_MAX; --tmp >= 0; )
Eric W. Biederman92476d72006-03-31 02:31:42 -0800291 if (!hlist_empty(&pid->tasks[tmp]))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 return;
293
Eric W. Biederman92476d72006-03-31 02:31:42 -0800294 free_pid(pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295}
296
Oleg Nesterov24336eae2008-04-30 00:54:26 -0700297void detach_pid(struct task_struct *task, enum pid_type type)
298{
299 __change_pid(task, type, NULL);
300}
301
302void change_pid(struct task_struct *task, enum pid_type type,
303 struct pid *pid)
304{
305 __change_pid(task, type, pid);
Oleg Nesterov81907732013-07-03 15:08:31 -0700306 attach_pid(task, type);
Oleg Nesterov24336eae2008-04-30 00:54:26 -0700307}
308
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700309/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800310void transfer_pid(struct task_struct *old, struct task_struct *new,
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700311 enum pid_type type)
312{
313 new->pids[type].pid = old->pids[type].pid;
314 hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
Eric W. Biedermanc18258c2006-09-27 01:51:06 -0700315}
316
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800317struct task_struct *pid_task(struct pid *pid, enum pid_type type)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800318{
319 struct task_struct *result = NULL;
320 if (pid) {
321 struct hlist_node *first;
Arnd Bergmann67bdbff2010-02-25 16:55:13 +0100322 first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
Paul E. McKenneydb1466b2010-03-03 07:46:56 -0800323 lockdep_tasklist_lock_is_held());
Eric W. Biederman92476d72006-03-31 02:31:42 -0800324 if (first)
325 result = hlist_entry(first, struct task_struct, pids[(type)].node);
326 }
327 return result;
328}
Pavel Emelyanoveccba062008-02-07 00:13:21 -0800329EXPORT_SYMBOL(pid_task);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800330
331/*
Tetsuo Handa9728e5d2010-03-05 13:42:56 -0800332 * Must be called under rcu_read_lock().
Eric W. Biederman92476d72006-03-31 02:31:42 -0800333 */
Christoph Hellwig17f98dc2009-06-17 16:27:51 -0700334struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335{
Paul E. McKenneyf78f5b92015-06-18 15:50:02 -0700336 RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
337 "find_task_by_pid_ns() needs rcu_read_lock() protection");
Christoph Hellwig17f98dc2009-06-17 16:27:51 -0700338 return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
340
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700341struct task_struct *find_task_by_vpid(pid_t vnr)
342{
Eric W. Biederman17cf22c2010-03-02 14:51:53 -0800343 return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700344}
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700345
Mike Rapoport2ee08262018-02-06 15:40:17 -0800346struct task_struct *find_get_task_by_vpid(pid_t nr)
347{
348 struct task_struct *task;
349
350 rcu_read_lock();
351 task = find_task_by_vpid(nr);
352 if (task)
353 get_task_struct(task);
354 rcu_read_unlock();
355
356 return task;
357}
358
Oleg Nesterov1a657f782006-10-02 02:18:59 -0700359struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
360{
361 struct pid *pid;
362 rcu_read_lock();
Oleg Nesterov2ae448e2009-04-02 16:58:36 -0700363 if (type != PIDTYPE_PID)
364 task = task->group_leader;
Eric Dumazet81b1a832015-11-24 11:39:54 -0800365 pid = get_pid(rcu_dereference(task->pids[type].pid));
Oleg Nesterov1a657f782006-10-02 02:18:59 -0700366 rcu_read_unlock();
367 return pid;
368}
Rik van Riel77c100c2011-02-01 09:51:46 -0500369EXPORT_SYMBOL_GPL(get_task_pid);
Oleg Nesterov1a657f782006-10-02 02:18:59 -0700370
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -0800371struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
Eric W. Biederman92476d72006-03-31 02:31:42 -0800372{
373 struct task_struct *result;
374 rcu_read_lock();
375 result = pid_task(pid, type);
376 if (result)
377 get_task_struct(result);
378 rcu_read_unlock();
379 return result;
380}
Rik van Riel77c100c2011-02-01 09:51:46 -0500381EXPORT_SYMBOL_GPL(get_pid_task);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800382
383struct pid *find_get_pid(pid_t nr)
384{
385 struct pid *pid;
386
387 rcu_read_lock();
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700388 pid = get_pid(find_vpid(nr));
Eric W. Biederman92476d72006-03-31 02:31:42 -0800389 rcu_read_unlock();
390
391 return pid;
392}
David Sterba339caf22008-07-25 01:48:31 -0700393EXPORT_SYMBOL_GPL(find_get_pid);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800394
Pavel Emelyanov7af57292007-10-18 23:40:06 -0700395pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
396{
397 struct upid *upid;
398 pid_t nr = 0;
399
400 if (pid && ns->level <= pid->level) {
401 upid = &pid->numbers[ns->level];
402 if (upid->ns == ns)
403 nr = upid->nr;
404 }
405 return nr;
406}
Eric W. Biederman4f82f452012-05-24 10:37:59 -0600407EXPORT_SYMBOL_GPL(pid_nr_ns);
Pavel Emelyanov7af57292007-10-18 23:40:06 -0700408
Eric W. Biederman44c4e1b2008-02-08 04:19:15 -0800409pid_t pid_vnr(struct pid *pid)
410{
Eric W. Biederman17cf22c2010-03-02 14:51:53 -0800411 return pid_nr_ns(pid, task_active_pid_ns(current));
Eric W. Biederman44c4e1b2008-02-08 04:19:15 -0800412}
413EXPORT_SYMBOL_GPL(pid_vnr);
414
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700415pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
416 struct pid_namespace *ns)
Pavel Emelyanov2f2a3a42007-10-18 23:40:19 -0700417{
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700418 pid_t nr = 0;
419
420 rcu_read_lock();
421 if (!ns)
Eric W. Biederman17cf22c2010-03-02 14:51:53 -0800422 ns = task_active_pid_ns(current);
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700423 if (likely(pid_alive(task))) {
Oleg Nesterovdd1c1f22017-08-21 17:35:02 +0200424 if (type != PIDTYPE_PID) {
425 if (type == __PIDTYPE_TGID)
426 type = PIDTYPE_PID;
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800427
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700428 task = task->group_leader;
Oleg Nesterovdd1c1f22017-08-21 17:35:02 +0200429 }
Eric Dumazet81b1a832015-11-24 11:39:54 -0800430 nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700431 }
432 rcu_read_unlock();
433
434 return nr;
Pavel Emelyanov2f2a3a42007-10-18 23:40:19 -0700435}
Oleg Nesterov52ee2df2009-04-02 16:58:38 -0700436EXPORT_SYMBOL(__task_pid_nr_ns);
Pavel Emelyanov2f2a3a42007-10-18 23:40:19 -0700437
Eric W. Biederman61bce0f2009-01-07 18:08:49 -0800438struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
439{
440 return ns_of_pid(task_pid(tsk));
441}
442EXPORT_SYMBOL_GPL(task_active_pid_ns);
443
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444/*
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200445 * Used by proc to find the first pid that is greater than or equal to nr.
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700446 *
Pavel Emelyanove49859e2008-07-25 01:48:36 -0700447 * 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 -0700448 */
Pavel Emelyanov198fe212007-10-18 23:40:06 -0700449struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700450{
Gargi Sharma95846ec2017-11-17 15:30:30 -0800451 return idr_get_next(&ns->idr, &nr);
Eric W. Biederman0804ef42006-10-02 02:17:04 -0700452}
453
Gargi Sharma95846ec2017-11-17 15:30:30 -0800454void __init pid_idr_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455{
Zhen Lei840d6fe2016-01-30 10:04:17 +0800456 /* Verify no one has done anything silly: */
Gargi Sharmae8cfbc22017-11-17 15:30:34 -0800457 BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
Eric W. Biedermanc876ad762012-12-21 20:27:12 -0800458
Hedi Berriche72680a12010-05-26 14:44:06 -0700459 /* bump default and minimum pid_max based on number of cpus */
460 pid_max = min(pid_max_max, max_t(int, pid_max,
461 PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
462 pid_max_min = max_t(int, pid_max_min,
463 PIDS_PER_CPU_MIN * num_possible_cpus());
464 pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);
465
Gargi Sharma95846ec2017-11-17 15:30:30 -0800466 idr_init(&init_pid_ns.idr);
Eric W. Biederman92476d72006-03-31 02:31:42 -0800467
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800468 init_pid_ns.pid_cachep = KMEM_CACHE(pid,
Vladimir Davydov5d097052016-01-14 15:18:21 -0800469 SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470}