Commit 8ef047aa authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by Linus Torvalds
Browse files

pid namespaces: make alloc_pid(), free_pid() and put_pid() work with struct upid 



Each struct upid element of struct pid has to be initialized properly, i.e.
its nr mst be allocated from appropriate pidmap and ns set to appropriate
namespace.

When allocating a new pid, we need to know the namespace this pid will live
in, so the additional argument is added to alloc_pid().

On the other hand, the rest of the kernel still uses the pid->nr and
pid->pid_chain fields, so these ones are still initialized, but this will be
removed soon.

Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent faacbfd3

include/linux/pid.h

+1 −1
Original line number Original line Diff line number Diff line
@@ -111,7 +111,7 @@ extern struct pid *FASTCALL(find_pid(int nr)); 
extern struct pid *find_get_pid(int nr);

extern struct pid *find_get_pid(int nr);

extern struct pid *find_ge_pid(int nr);

extern struct pid *find_ge_pid(int nr);





extern struct pid *alloc_pid(void);

extern struct pid *alloc_pid(struct pid_namespace *ns);

extern void FASTCALL(free_pid(struct pid *pid));

extern void FASTCALL(free_pid(struct pid *pid));





static inline pid_t pid_nr(struct pid *pid)

static inline pid_t pid_nr(struct pid *pid)

kernel/fork.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -1041,7 +1041,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, 
		goto bad_fork_cleanup_put_domain;

		goto bad_fork_cleanup_put_domain;





	if (pid != &init_struct_pid) {

	if (pid != &init_struct_pid) {

		pid = alloc_pid();

		pid = alloc_pid(task_active_pid_ns(p));

		if (!pid)

		if (!pid)

			goto bad_fork_put_binfmt_module;

			goto bad_fork_put_binfmt_module;

	}

	}

kernel/pid.c

+34 −15
Original line number Original line Diff line number Diff line
@@ -29,7 +29,8 @@ 
#include <linux/pid_namespace.h>

#include <linux/pid_namespace.h>

#include <linux/init_task.h>

#include <linux/init_task.h>





#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)

#define pid_hashfn(nr, ns)	\

	hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)

static struct hlist_head *pid_hash;

static struct hlist_head *pid_hash;

static int pidhash_shift;

static int pidhash_shift;

struct pid init_struct_pid = INIT_STRUCT_PID;

struct pid init_struct_pid = INIT_STRUCT_PID;
@@ -186,11 +187,13 @@ fastcall void put_pid(struct pid *pid) 
	if (!pid)

	if (!pid)

		return;

		return;





	/* FIXME - this must be the namespace this pid lives in */

	ns = pid->numbers[pid->level].ns;

	ns = &init_pid_ns;

	if ((atomic_read(&pid->count) == 1) ||

	if ((atomic_read(&pid->count) == 1) ||

	     atomic_dec_and_test(&pid->count))

	     atomic_dec_and_test(&pid->count)) {

		kmem_cache_free(ns->pid_cachep, pid);

		kmem_cache_free(ns->pid_cachep, pid);

		if (ns != &init_pid_ns)

			put_pid_ns(ns);

	}

}

}

EXPORT_SYMBOL_GPL(put_pid);

EXPORT_SYMBOL_GPL(put_pid);
@@ -203,45 +206,61 @@ static void delayed_put_pid(struct rcu_head *rhp) 
fastcall void free_pid(struct pid *pid)

fastcall void free_pid(struct pid *pid)

{

{

	/* We can be called with write_lock_irq(&tasklist_lock) held */

	/* We can be called with write_lock_irq(&tasklist_lock) held */

	int i;

	unsigned long flags;

	unsigned long flags;





	spin_lock_irqsave(&pidmap_lock, flags);

	spin_lock_irqsave(&pidmap_lock, flags);

	hlist_del_rcu(&pid->pid_chain);

	hlist_del_rcu(&pid->pid_chain);

	spin_unlock_irqrestore(&pidmap_lock, flags);

	spin_unlock_irqrestore(&pidmap_lock, flags);





	free_pidmap(&init_pid_ns, pid->nr);

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

		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);



	call_rcu(&pid->rcu, delayed_put_pid);

	call_rcu(&pid->rcu, delayed_put_pid);

}

}





struct pid *alloc_pid(void)

struct pid *alloc_pid(struct pid_namespace *ns)

{

{

	struct pid *pid;

	struct pid *pid;

	enum pid_type type;

	enum pid_type type;

	int nr = -1;

	int i, nr;

	struct pid_namespace *ns;

	struct pid_namespace *tmp;





	ns = task_active_pid_ns(current);

	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);

	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);

	if (!pid)

	if (!pid)

		goto out;

		goto out;





	nr = alloc_pidmap(ns);

	tmp = ns;

	for (i = ns->level; i >= 0; i--) {

		nr = alloc_pidmap(tmp);

		if (nr < 0)

		if (nr < 0)

			goto out_free;

			goto out_free;





		pid->numbers[i].nr = nr;

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

		tmp = tmp->parent;

	}



	if (ns != &init_pid_ns)

		get_pid_ns(ns);



	pid->level = ns->level;

	pid->nr = pid->numbers[0].nr;

	atomic_set(&pid->count, 1);

	atomic_set(&pid->count, 1);

	pid->nr = nr;

	for (type = 0; type < PIDTYPE_MAX; ++type)

	for (type = 0; type < PIDTYPE_MAX; ++type)

		INIT_HLIST_HEAD(&pid->tasks[type]);

		INIT_HLIST_HEAD(&pid->tasks[type]);





	spin_lock_irq(&pidmap_lock);

	spin_lock_irq(&pidmap_lock);

	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);

	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, ns)]);

	spin_unlock_irq(&pidmap_lock);

	spin_unlock_irq(&pidmap_lock);





out:

out:

	return pid;

	return pid;





out_free:

out_free:

	for (i++; i <= ns->level; i++)

		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);



	kmem_cache_free(ns->pid_cachep, pid);

	kmem_cache_free(ns->pid_cachep, pid);

	pid = NULL;

	pid = NULL;

	goto out;

	goto out;
@@ -253,7 +272,7 @@ struct pid * fastcall find_pid(int nr) 
	struct pid *pid;

	struct pid *pid;





	hlist_for_each_entry_rcu(pid, elem,

	hlist_for_each_entry_rcu(pid, elem,

			&pid_hash[pid_hashfn(nr)], pid_chain) {

			&pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {

		if (pid->nr == nr)

		if (pid->nr == nr)

			return pid;

			return pid;

	}

	}

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