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

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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: Pavel 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pavel Emelyanov 2007-10-18 23:40:05 -07:00 committed by Linus Torvalds
parent faacbfd3a6
commit 8ef047aaae
3 changed files with 36 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
include/linux/pid.h
View file

@ -111,7 +111,7 @@ extern struct pid *FASTCALL(find_pid(int nr));
extern struct pid *find_get_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));
static inline pid_t pid_nr(struct pid *pid)

2
kernel/fork.c
View file

@ -1041,7 +1041,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto bad_fork_cleanup_put_domain;
if (pid != &init_struct_pid) {
pid = alloc_pid();
pid = alloc_pid(task_active_pid_ns(p));
if (!pid)
goto bad_fork_put_binfmt_module;
}

45
kernel/pid.c
View file

@ -29,7 +29,8 @@
#include <linux/pid_namespace.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 int pidhash_shift;
struct pid init_struct_pid = INIT_STRUCT_PID;
@ -186,11 +187,13 @@ fastcall void put_pid(struct pid *pid)
if (!pid)
return;
/* FIXME - this must be the namespace this pid lives in */
ns = &init_pid_ns;
ns = pid->numbers[pid->level].ns;
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);
if (ns != &init_pid_ns)
put_pid_ns(ns);
}
}
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)
{
/* We can be called with write_lock_irq(&tasklist_lock) held */
int i;
unsigned long flags;
spin_lock_irqsave(&pidmap_lock, flags);
hlist_del_rcu(&pid->pid_chain);
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);
}
struct pid *alloc_pid(void)
struct pid *alloc_pid(struct pid_namespace *ns)
{
struct pid *pid;
enum pid_type type;
int nr = -1;
struct pid_namespace *ns;
int i, nr;
struct pid_namespace *tmp;
ns = task_active_pid_ns(current);
pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
if (!pid)
goto out;
nr = alloc_pidmap(ns);
tmp = ns;
for (i = ns->level; i >= 0; i--) {
nr = alloc_pidmap(tmp);
if (nr < 0)
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);
pid->nr = nr;
for (type = 0; type < PIDTYPE_MAX; ++type)
INIT_HLIST_HEAD(&pid->tasks[type]);
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);
out:
return pid;
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);
pid = NULL;
goto out;
@ -253,7 +272,7 @@ struct pid * fastcall find_pid(int nr)
struct pid *pid;
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)
return pid;
}