Release 4.9 kernel/pid.c

/*
 * Generic pidhash and scalable, time-bounded PID allocator
 *
 * (C) 2002-2003 Nadia Yvette Chambers, IBM
 * (C) 2004 Nadia Yvette Chambers, Oracle
 * (C) 2002-2004 Ingo Molnar, Red Hat
 *
 * pid-structures are backing objects for tasks sharing a given ID to chain
 * against. There is very little to them aside from hashing them and
 * parking tasks using given ID's on a list.
 *
 * The hash is always changed with the tasklist_lock write-acquired,
 * and the hash is only accessed with the tasklist_lock at least
 * read-acquired, so there's no additional SMP locking needed here.
 *
 * We have a list of bitmap pages, which bitmaps represent the PID space.
 * Allocating and freeing PIDs is completely lockless. The worst-case
 * allocation scenario when all but one out of 1 million PIDs possible are
 * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
 * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
 *
 * Pid namespaces:
 *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
 *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
 *     Many thanks to Oleg Nesterov for comments and help
 *
 */

#include <linux/mm.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/rculist.h>
#include <linux/bootmem.h>
#include <linux/hash.h>
#include <linux/pid_namespace.h>
#include <linux/init_task.h>
#include <linux/syscalls.h>
#include <linux/proc_ns.h>
#include <linux/proc_fs.h>


#define pid_hashfn(nr, ns)	\
	hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)

static struct hlist_head *pid_hash;

static unsigned int pidhash_shift = 4;

struct pid init_struct_pid = INIT_STRUCT_PID;


int pid_max = PID_MAX_DEFAULT;


#define RESERVED_PIDS		300


int pid_max_min = RESERVED_PIDS + 1;

int pid_max_max = PID_MAX_LIMIT;



static inline int mk_pid(struct pid_namespace *pid_ns,
		struct pidmap *map, int off)
{
	return (map - pid_ns->pidmap)*BITS_PER_PAGE + off;
}

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william lee irwin iii
william lee irwin iii
6
18.18%
1
33.33%
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33
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3
100.00%


#define find_next_offset(map, off)					\
		find_next_zero_bit((map)->page, BITS_PER_PAGE, off)

/*
 * PID-map pages start out as NULL, they get allocated upon
 * first use and are never deallocated. This way a low pid_max
 * value does not cause lots of bitmaps to be allocated, but
 * the scheme scales to up to 4 million PIDs, runtime.
 */

struct pid_namespace init_pid_ns = {
	.kref = {
		.refcount       = ATOMIC_INIT(2),
        },
	.pidmap = {
		[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
	},
	.last_pid = 0,
	.nr_hashed = PIDNS_HASH_ADDING,
	.level = 0,
	.child_reaper = &init_task,
	.user_ns = &init_user_ns,
	.ns.inum = PROC_PID_INIT_INO,
#ifdef CONFIG_PID_NS
	.ns.ops = &pidns_operations,
#endif
};

EXPORT_SYMBOL_GPL(init_pid_ns);

/*
 * Note: disable interrupts while the pidmap_lock is held as an
 * interrupt might come in and do read_lock(&tasklist_lock).
 *
 * If we don't disable interrupts there is a nasty deadlock between
 * detach_pid()->free_pid() and another cpu that does
 * spin_lock(&pidmap_lock) followed by an interrupt routine that does
 * read_lock(&tasklist_lock);
 *
 * After we clean up the tasklist_lock and know there are no
 * irq handlers that take it we can leave the interrupts enabled.
 * For now it is easier to be safe than to prove it can't happen.
 */

static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock);



static void free_pidmap(struct upid *upid)
{
	int nr = upid->nr;
	struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE;
	int offset = nr & BITS_PER_PAGE_MASK;

	clear_bit(offset, map->page);
	atomic_inc(&map->nr_free);
}

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ingo molnar
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oleg nesterov
14
24.56%
1
20.00%
sukadev bhattiprolu
sukadev bhattiprolu
6
10.53%
2
40.00%
eric w. biederman
eric w. biederman
1
1.75%
1
20.00%
Total
57
100.00%
5
100.00%

/*
 * If we started walking pids at 'base', is 'a' seen before 'b'?
 */


static int pid_before(int base, int a, int b)
{
	/*
         * This is the same as saying
         *
         * (a - base + MAXUINT) % MAXUINT < (b - base + MAXUINT) % MAXUINT
         * and that mapping orders 'a' and 'b' with respect to 'base'.
         */
	return (unsigned)(a - base) < (unsigned)(b - base);
}

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salman qazi
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35
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1
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/*
 * We might be racing with someone else trying to set pid_ns->last_pid
 * at the pid allocation time (there's also a sysctl for this, but racing
 * with this one is OK, see comment in kernel/pid_namespace.c about it).
 * We want the winner to have the "later" value, because if the
 * "earlier" value prevails, then a pid may get reused immediately.
 *
 * Since pids rollover, it is not sufficient to just pick the bigger
 * value.  We have to consider where we started counting from.
 *
 * 'base' is the value of pid_ns->last_pid that we observed when
 * we started looking for a pid.
 *
 * 'pid' is the pid that we eventually found.
 */


static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid)
{
	int prev;
	int last_write = base;
	do {
		prev = last_write;
		last_write = cmpxchg(&pid_ns->last_pid, prev, pid);
	} while ((prev != last_write) && (pid_before(base, last_write, pid)));
}

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salman qazi
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66
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1
100.00%



static int alloc_pidmap(struct pid_namespace *pid_ns)
{
	int i, offset, max_scan, pid, last = pid_ns->last_pid;
	struct pidmap *map;

	pid = last + 1;
	if (pid >= pid_max)
		pid = RESERVED_PIDS;
	offset = pid & BITS_PER_PAGE_MASK;
	map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
	/*
         * If last_pid points into the middle of the map->page we
         * want to scan this bitmap block twice, the second time
         * we start with offset == 0 (or RESERVED_PIDS).
         */
	max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset;
	for (i = 0; i <= max_scan; ++i) {
		if (unlikely(!map->page)) {
			void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
			/*
                         * Free the page if someone raced with us
                         * installing it:
                         */
			spin_lock_irq(&pidmap_lock);
			if (!map->page) {
				map->page = page;
				page = NULL;
			}
			spin_unlock_irq(&pidmap_lock);
			kfree(page);
			if (unlikely(!map->page))
				return -ENOMEM;
		}
		if (likely(atomic_read(&map->nr_free))) {
			for ( ; ; ) {
				if (!test_and_set_bit(offset, map->page)) {
					atomic_dec(&map->nr_free);
					set_last_pid(pid_ns, last, pid);
					return pid;
				}
				offset = find_next_offset(map, offset);
				if (offset >= BITS_PER_PAGE)
					break;
				pid = mk_pid(pid_ns, map, offset);
				if (pid >= pid_max)
					break;
			}
		}
		if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
			++map;
			offset = 0;
		} else {
			map = &pid_ns->pidmap[0];
			offset = RESERVED_PIDS;
			if (unlikely(last == offset))
				break;
		}
		pid = mk_pid(pid_ns, map, offset);
	}
	return -EAGAIN;
}

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ingo molnar
ingo molnar
131
40.18%
2
16.67%
william lee irwin iii
william lee irwin iii
121
37.12%
1
8.33%
sukadev bhattiprolu
sukadev bhattiprolu
27
8.28%
3
25.00%
raphael s. carvalho
raphael s. carvalho
16
4.91%
1
8.33%
andre goddard rosa
andre goddard rosa
12
3.68%
1
8.33%
salman qazi
salman qazi
6
1.84%
1
8.33%
michal hocko
michal hocko
5
1.53%
1
8.33%
oleg nesterov
oleg nesterov
5
1.53%
1
8.33%
eric w. biederman
eric w. biederman
3
0.92%
1
8.33%
Total
326
100.00%
12
100.00%



int next_pidmap(struct pid_namespace *pid_ns, unsigned int last)
{
	int offset;
	struct pidmap *map, *end;

	if (last >= PID_MAX_LIMIT)
		return -1;

	offset = (last + 1) & BITS_PER_PAGE_MASK;
	map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
	end = &pid_ns->pidmap[PIDMAP_ENTRIES];
	for (; map < end; map++, offset = 0) {
		if (unlikely(!map->page))
			continue;
		offset = find_next_bit((map)->page, BITS_PER_PAGE, offset);
		if (offset < BITS_PER_PAGE)
			return mk_pid(pid_ns, map, offset);
	}
	return -1;
}

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eric w. biederman
eric w. biederman
117
87.97%
3
60.00%
linus torvalds
linus torvalds
11
8.27%
1
20.00%
sukadev bhattiprolu
sukadev bhattiprolu
5
3.76%
1
20.00%
Total
133
100.00%
5
100.00%



void put_pid(struct pid *pid)
{
	struct pid_namespace *ns;

	if (!pid)
		return;

	ns = pid->numbers[pid->level].ns;
	if ((atomic_read(&pid->count) == 1) ||
	     atomic_dec_and_test(&pid->count)) {
		kmem_cache_free(ns->pid_cachep, pid);
		put_pid_ns(ns);
	}
}
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eric w. biederman
eric w. biederman
31
43.06%
1
20.00%
pavel emelianov
pavel emelianov
27
37.50%
2
40.00%
ingo molnar
ingo molnar
13
18.06%
1
20.00%
nick piggin
nick piggin
1
1.39%
1
20.00%
Total
72
100.00%
5
100.00%


EXPORT_SYMBOL_GPL(put_pid);



static void delayed_put_pid(struct rcu_head *rhp)
{
	struct pid *pid = container_of(rhp, struct pid, rcu);
	put_pid(pid);
}

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eric w. biederman
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61.29%
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ingo molnar
12
38.71%
1
50.00%
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31
100.00%
2
100.00%



void free_pid(struct pid *pid)
{
	/* We can be called with write_lock_irq(&tasklist_lock) held */
	int i;
	unsigned long flags;

	spin_lock_irqsave(&pidmap_lock, flags);
	for (i = 0; i <= pid->level; i++) {
		struct upid *upid = pid->numbers + i;
		struct pid_namespace *ns = upid->ns;
		hlist_del_rcu(&upid->pid_chain);
		switch(--ns->nr_hashed) {
		case 2:
		case 1:
			/* When all that is left in the pid namespace
                         * is the reaper wake up the reaper.  The reaper
                         * may be sleeping in zap_pid_ns_processes().
                         */
			wake_up_process(ns->child_reaper);
			break;
		case PIDNS_HASH_ADDING:
			/* Handle a fork failure of the first process */
			WARN_ON(ns->child_reaper);
			ns->nr_hashed = 0;
			/* fall through */
		case 0:
			schedule_work(&ns->proc_work);
			break;
		}
	}
	spin_unlock_irqrestore(&pidmap_lock, flags);

	for (i = 0; i <= pid->level; i++)
		free_pidmap(pid->numbers + i);

	call_rcu(&pid->rcu, delayed_put_pid);
}

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eric w. biederman
eric w. biederman
88
52.69%
5
41.67%
pavel emelianov
pavel emelianov
39
23.35%
2
16.67%
oleg nesterov
oleg nesterov
19
11.38%
2
16.67%
ingo molnar
ingo molnar
15
8.98%
2
16.67%
kirill korotaev
kirill korotaev
6
3.59%
1
8.33%
Total
167
100.00%
12
100.00%



struct pid *alloc_pid(struct pid_namespace *ns)
{
	struct pid *pid;
	enum pid_type type;
	int i, nr;
	struct pid_namespace *tmp;
	struct upid *upid;
	int retval = -ENOMEM;

	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
	if (!pid)
		return ERR_PTR(retval);

	tmp = ns;
	pid->level = ns->level;
	for (i = ns->level; i >= 0; i--) {
		nr = alloc_pidmap(tmp);
		if (nr < 0) {
			retval = nr;
			goto out_free;
		}

		pid->numbers[i].nr = nr;
		pid->numbers[i].ns = tmp;
		tmp = tmp->parent;
	}

	if (unlikely(is_child_reaper(pid))) {
		if (pid_ns_prepare_proc(ns))
			goto out_free;
	}

	get_pid_ns(ns);
	atomic_set(&pid->count, 1);
	for (type = 0; type < PIDTYPE_MAX; ++type)
		INIT_HLIST_HEAD(&pid->tasks[type]);

	upid = pid->numbers + ns->level;
	spin_lock_irq(&pidmap_lock);
	if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
		goto out_unlock;
	for ( ; upid >= pid->numbers; --upid) {
		hlist_add_head_rcu(&upid->pid_chain,
				&pid_hash[pid_hashfn(upid->nr, upid->ns)]);
		upid->ns->nr_hashed++;
	}
	spin_unlock_irq(&pidmap_lock);

	return pid;

out_unlock:
	spin_unlock_irq(&pidmap_lock);
	put_pid_ns(ns);

out_free:
	while (++i <= ns->level)
		free_pidmap(pid->numbers + i);

	kmem_cache_free(ns->pid_cachep, pid);
	return ERR_PTR(retval);
}

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eric w. biederman
127
37.91%
5
29.41%
pavel emelianov
pavel emelianov
109
32.54%
3
17.65%
ingo molnar
ingo molnar
32
9.55%
2
11.76%
michal hocko
michal hocko
24
7.16%
1
5.88%
andre goddard rosa
andre goddard rosa
15
4.48%
1
5.88%
kirill korotaev
kirill korotaev
15
4.48%
1
5.88%
oleg nesterov
oleg nesterov
9
2.69%
2
11.76%
arnd bergmann
arnd bergmann
2
0.60%
1
5.88%
sukadev bhattiprolu
sukadev bhattiprolu
2
0.60%
1
5.88%
Total
335
100.00%
17
100.00%



void disable_pid_allocation(struct pid_namespace *ns)
{
	spin_lock_irq(&pidmap_lock);
	ns->nr_hashed &= ~PIDNS_HASH_ADDING;
	spin_unlock_irq(&pidmap_lock);
}

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29
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1
100.00%



struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
{
	struct upid *pnr;

	hlist_for_each_entry_rcu(pnr,
			&pid_hash[pid_hashfn(nr, ns)], pid_chain)
		if (pnr->nr == nr && pnr->ns == ns)
			return container_of(pnr, struct pid,
					numbers[ns->level]);

	return NULL;
}
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pavel emelianov
pavel emelianov
30
49.18%
1
33.33%
eric w. biederman
eric w. biederman
29
47.54%
1
33.33%
kirill korotaev
kirill korotaev
2
3.28%
1
33.33%
Total
61
100.00%
3
100.00%


EXPORT_SYMBOL_GPL(find_pid_ns);



struct pid *find_vpid(int nr)
{
	return find_pid_ns(nr, task_active_pid_ns(current));
}
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pavel emelianov
pavel emelianov
18
85.71%
1
50.00%
eric w. biederman
eric w. biederman
3
14.29%
1
50.00%
Total
21
100.00%
2
100.00%


EXPORT_SYMBOL_GPL(find_vpid);

/*
 * attach_pid() must be called with the tasklist_lock write-held.
 */


void attach_pid(struct task_struct *task, enum pid_type type)
{
	struct pid_link *link = &task->pids[type];
	hlist_add_head_rcu(&link->node, &link->pid->tasks[type]);
}

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eric w. biederman
37
82.22%
1
20.00%
oleg nesterov
oleg nesterov
5
11.11%
2
40.00%
ingo molnar
ingo molnar
3
6.67%
2
40.00%
Total
45
100.00%
5
100.00%



static void __change_pid(struct task_struct *task, enum pid_type type,
			struct pid *new)
{
	struct pid_link *link;
	struct pid *pid;
	int tmp;

	link = &task->pids[type];
	pid = link->pid;

	hlist_del_rcu(&link->node);
	link->pid = new;

	for (tmp = PIDTYPE_MAX; --tmp >= 0; )
		if (!hlist_empty(&pid->tasks[tmp]))
			return;

	free_pid(pid);
}

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eric w. biederman
eric w. biederman
44
46.32%
1
14.29%
ingo molnar
ingo molnar
32
33.68%
3
42.86%
oleg nesterov
oleg nesterov
16
16.84%
2
28.57%
kirill korotaev
kirill korotaev
3
3.16%
1
14.29%
Total
95
100.00%
7
100.00%



void detach_pid(struct task_struct *task, enum pid_type type)
{
	__change_pid(task, type, NULL);
}

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oleg nesterov
oleg nesterov
23
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1
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23
100.00%
1
100.00%



void change_pid(struct task_struct *task, enum pid_type type,
		struct pid *pid)
{
	__change_pid(task, type, pid);
	attach_pid(task, type);
}

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35
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1
100.00%

/* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */


void transfer_pid(struct task_struct *old, struct task_struct *new,
			   enum pid_type type)
{
	new->pids[type].pid = old->pids[type].pid;
	hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node);
}

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struct task_struct *pid_task(struct pid *pid, enum pid_type type)
{
	struct task_struct *result = NULL;
	if (pid) {
		struct hlist_node *first;
		first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
					      lockdep_tasklist_lock_is_held());
		if (first)
			result = hlist_entry(first, struct task_struct, pids[(type)].node);
	}
	return result;
}
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eric w. biederman
eric w. biederman
52
65.82%
1
16.67%
ingo molnar
ingo molnar
13
16.46%
1
16.67%
kirill korotaev
kirill korotaev
6
7.59%
1
16.67%
arnd bergmann
arnd bergmann
4
5.06%
1
16.67%
paul e. mckenney
paul e. mckenney
4
5.06%
2
33.33%
Total
79
100.00%
6
100.00%


EXPORT_SYMBOL(pid_task);

/*
 * Must be called under rcu_read_lock().
 */


struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
{
	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
			 "find_task_by_pid_ns() needs rcu_read_lock() protection");
	return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID);
}

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ingo molnar
ingo molnar
9
24.32%
2
25.00%
eric w. biederman
eric w. biederman
8
21.62%
1
12.50%
pavel emelianov
pavel emelianov
8
21.62%
1
12.50%
tetsuo handa
tetsuo handa
5
13.51%
1
12.50%
paul e. mckenney
paul e. mckenney
4
10.81%
2
25.00%
christoph hellwig
christoph hellwig
3
8.11%
1
12.50%
Total
37
100.00%
8
100.00%



struct task_struct *find_task_by_vpid(pid_t vnr)
{
	return find_task_by_pid_ns(vnr, task_active_pid_ns(current));
}

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1
33.33%
eric w. biederman
eric w. biederman
3
14.29%
1
33.33%
christoph hellwig
christoph hellwig
1
4.76%
1
33.33%
Total
21
100.00%
3
100.00%



struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
{
	struct pid *pid;
	rcu_read_lock();
	if (type != PIDTYPE_PID)
		task = task->group_leader;
	pid = get_pid(rcu_dereference(task->pids[type].pid));
	rcu_read_unlock();
	return pid;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
oleg nesterov
oleg nesterov
56
94.92%
2
66.67%
eric dumazet
eric dumazet
3
5.08%
1
33.33%
Total
59
100.00%
3
100.00%


EXPORT_SYMBOL_GPL(get_task_pid);



struct task_struct *get_pid_task(struct pid *pid, enum pid_type type)
{
	struct task_struct *result;
	rcu_read_lock();
	result = pid_task(pid, type);
	if (result)
		get_task_struct(result);
	rcu_read_unlock();
	return result;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
48
100.00%
1
100.00%
Total
48
100.00%
1
100.00%


EXPORT_SYMBOL_GPL(get_pid_task);



struct pid *find_get_pid(pid_t nr)
{
	struct pid *pid;

	rcu_read_lock();
	pid = get_pid(find_vpid(nr));
	rcu_read_unlock();

	return pid;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
33
97.06%
1
50.00%
pavel emelianov
pavel emelianov
1
2.94%
1
50.00%
Total
34
100.00%
2
100.00%


EXPORT_SYMBOL_GPL(find_get_pid);



pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
{
	struct upid *upid;
	pid_t nr = 0;

	if (pid && ns->level <= pid->level) {
		upid = &pid->numbers[ns->level];
		if (upid->ns == ns)
			nr = upid->nr;
	}
	return nr;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
pavel emelianov
pavel emelianov
68
100.00%
1
100.00%
Total
68
100.00%
1
100.00%


EXPORT_SYMBOL_GPL(pid_nr_ns);



pid_t pid_vnr(struct pid *pid)
{
	return pid_nr_ns(pid, task_active_pid_ns(current));
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
21
100.00%
2
100.00%
Total
21
100.00%
2
100.00%


EXPORT_SYMBOL_GPL(pid_vnr);



pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
			struct pid_namespace *ns)
{
	pid_t nr = 0;

	rcu_read_lock();
	if (!ns)
		ns = task_active_pid_ns(current);
	if (likely(pid_alive(task))) {
		if (type != PIDTYPE_PID)
			task = task->group_leader;
		nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
	}
	rcu_read_unlock();

	return nr;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
oleg nesterov
oleg nesterov
55
62.50%
1
25.00%
pavel emelianov
pavel emelianov
27
30.68%
1
25.00%
eric w. biederman
eric w. biederman
3
3.41%
1
25.00%
eric dumazet
eric dumazet
3
3.41%
1
25.00%
Total
88
100.00%
4
100.00%


EXPORT_SYMBOL(__task_pid_nr_ns);



pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
{
	return pid_nr_ns(task_tgid(tsk), ns);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
pavel emelianov
pavel emelianov
24
92.31%
1
50.00%
oleg nesterov
oleg nesterov
2
7.69%
1
50.00%
Total
26
100.00%
2
100.00%


EXPORT_SYMBOL(task_tgid_nr_ns);



struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
{
	return ns_of_pid(task_pid(tsk));
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
21
100.00%
1
100.00%
Total
21
100.00%
1
100.00%


EXPORT_SYMBOL_GPL(task_active_pid_ns);

/*
 * Used by proc to find the first pid that is greater than or equal to nr.
 *
 * If there is a pid at nr this function is exactly the same as find_pid_ns.
 */


struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
{
	struct pid *pid;

	do {
		pid = find_pid_ns(nr, ns);
		if (pid)
			break;
		nr = next_pidmap(ns, nr);
	} while (nr > 0);

	return pid;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
47
83.93%
2
66.67%
pavel emelianov
pavel emelianov
9
16.07%
1
33.33%
Total
56
100.00%
3
100.00%

/*
 * The pid hash table is scaled according to the amount of memory in the
 * machine.  From a minimum of 16 slots up to 4096 slots at one gigabyte or
 * more.
 */


void __init pidhash_init(void)
{
	unsigned int i, pidhash_size;

	pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
					   HASH_EARLY | HASH_SMALL,
					   &pidhash_shift, NULL,
					   0, 4096);
	pidhash_size = 1U << pidhash_shift;

	for (i = 0; i < pidhash_size; i++)
		INIT_HLIST_HEAD(&pid_hash[i]);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
pavel emelianov
pavel emelianov
50
69.44%
2
40.00%
jan beulich
jan beulich
18
25.00%
1
20.00%
dimitri sivanich
dimitri sivanich
2
2.78%
1
20.00%
tim bird
tim bird
2
2.78%
1
20.00%
Total
72
100.00%
5
100.00%



void __init pidmap_init(void)
{
	/* Verify no one has done anything silly: */
	BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);

	/* bump default and minimum pid_max based on number of cpus */
	pid_max = min(pid_max_max, max_t(int, pid_max,
				PIDS_PER_CPU_DEFAULT * num_possible_cpus()));
	pid_max_min = max_t(int, pid_max_min,
				PIDS_PER_CPU_MIN * num_possible_cpus());
	pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min);

	init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
	/* Reserve PID 0. We never call free_pidmap(0) */
	set_bit(0, init_pid_ns.pidmap[0].page);
	atomic_dec(&init_pid_ns.pidmap[0].nr_free);

	init_pid_ns.pid_cachep = KMEM_CACHE(pid,
			SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
hedi berriche
hedi berriche
43
36.44%
1
7.69%
pavel emelianov
pavel emelianov
35
29.66%
3
23.08%
sukadev bhattiprolu
sukadev bhattiprolu
18
15.25%
3
23.08%
eric w. biederman
eric w. biederman
9
7.63%
2
15.38%
andrew morton
andrew morton
9
7.63%
1
7.69%
vladimir davydov
vladimir davydov
2
1.69%
1
7.69%
ingo molnar
ingo molnar
1
0.85%
1
7.69%
zhen lei
zhen lei
1
0.85%
1
7.69%
Total
118
100.00%
13
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
eric w. biederman
eric w. biederman
872
33.04%
18
19.15%
pavel emelianov
pavel emelianov
497
18.83%
12
12.77%
ingo molnar
ingo molnar
351
13.30%
5
5.32%
oleg nesterov
oleg nesterov
241
9.13%
10
10.64%
william lee irwin iii
william lee irwin iii
149
5.65%
2
2.13%
sukadev bhattiprolu
sukadev bhattiprolu
119
4.51%
9
9.57%
salman qazi
salman qazi
108
4.09%
1
1.06%
hedi berriche
hedi berriche
43
1.63%
1
1.06%
kirill korotaev
kirill korotaev
32
1.21%
1
1.06%
michal hocko
michal hocko
29
1.10%
1
1.06%
andre goddard rosa
andre goddard rosa
27
1.02%
2
2.13%
raphael s. carvalho
raphael s. carvalho
21
0.80%
2
2.13%
jan beulich
jan beulich
21
0.80%
1
1.06%
al viro
al viro
18
0.68%
2
2.13%
andrew morton
andrew morton
17
0.64%
1
1.06%
cedric le goater
cedric le goater
13
0.49%
1
1.06%
linus torvalds
linus torvalds
11
0.42%
1
1.06%
rik van riel
rik van riel
10
0.38%
1
1.06%
paul e. mckenney
paul e. mckenney
8
0.30%
4
4.26%
arnd bergmann
arnd bergmann
6
0.23%
2
2.13%
tetsuo handa
tetsuo handa
6
0.23%
2
2.13%
eric dumazet
eric dumazet
6
0.23%
1
1.06%
thomas gleixner
thomas gleixner
5
0.19%
1
1.06%
david sterba
david sterba
5
0.19%
1
1.06%
christoph hellwig
christoph hellwig
4
0.15%
1
1.06%
franck bui-huu
franck bui-huu
3
0.11%
1
1.06%
david howells
david howells
3
0.11%
1
1.06%
tim bird
tim bird
2
0.08%
1
1.06%
nick piggin
nick piggin
2
0.08%
1
1.06%
dimitri sivanich
dimitri sivanich
2
0.08%
1
1.06%
vladimir davydov
vladimir davydov
2
0.08%
1
1.06%
arnaldo carvalho de melo
arnaldo carvalho de melo
2
0.08%
1
1.06%
frederik schwarzer
frederik schwarzer
1
0.04%
1
1.06%
paul gortmaker
paul gortmaker
1
0.04%
1
1.06%
nadia yvette chambers
nadia yvette chambers
1
0.04%
1
1.06%
zhen lei
zhen lei
1
0.04%
1
1.06%
Total
2639
100.00%
94
100.00%
  
Directory: kernel