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pid namespaces: miscellaneous preparations for pid namespaces 

* remove pid.h from pid_namespaces.h;
* rework is_(cgroup|global)_init;
* optimize (get|put)_pid_ns for init_pid_ns;
* declare task_child_reaper to return actual reaper.

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 23:40:09 -07:00 committed by Linus Torvalds
parent 07543f5c75
commit b461cc0382
3 changed files with 25 additions and 18 deletions
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10
include/linux/pid_namespace.h
View File

@ -4,7 +4,6 @@
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/threads.h>
#include <linux/pid.h>
#include <linux/nsproxy.h>
#include <linux/kref.h>
@ -32,7 +31,8 @@ extern struct pid_namespace init_pid_ns;
static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
{
kref_get(&ns->kref);
if (ns != &init_pid_ns)
kref_get(&ns->kref);
return ns;
}
@ -41,7 +41,8 @@ extern void free_pid_ns(struct kref *kref);
static inline void put_pid_ns(struct pid_namespace *ns)
{
kref_put(&ns->kref, free_pid_ns);
if (ns != &init_pid_ns)
kref_put(&ns->kref, free_pid_ns);
}
static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
@ -51,7 +52,8 @@ static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
static inline struct task_struct *task_child_reaper(struct task_struct *tsk)
{
return init_pid_ns.child_reaper;
BUG_ON(tsk != current);
return tsk->nsproxy->pid_ns->child_reaper;
}
#endif /* _LINUX_PID_NS_H */

12
include/linux/sched.h
View File

@ -1329,19 +1329,17 @@ static inline int pid_alive(struct task_struct *p)
* @tsk: Task structure to be checked.
*
* Check if a task structure is the first user space task the kernel created.
*
* TODO: We should inline this function after some cleanups in pid_namespace.h
*/
extern int is_global_init(struct task_struct *tsk);
static inline int is_global_init(struct task_struct *tsk)
{
return tsk->pid == 1;
}
/*
* is_container_init:
* check whether in the task is init in its own pid namespace.
*/
static inline int is_container_init(struct task_struct *tsk)
{
return tsk->pid == 1;
}
extern int is_container_init(struct task_struct *tsk);
extern struct pid *cad_pid;

21
kernel/pid.c
View File

@ -73,10 +73,20 @@ struct pid_namespace init_pid_ns = {
};
EXPORT_SYMBOL_GPL(init_pid_ns);
int is_global_init(struct task_struct *tsk)
int is_container_init(struct task_struct *tsk)
{
return tsk == init_pid_ns.child_reaper;
int ret = 0;
struct pid *pid;
rcu_read_lock();
pid = task_pid(tsk);
if (pid != NULL && pid->numbers[pid->level].nr == 1)
ret = 1;
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL(is_container_init);
/*
* Note: disable interrupts while the pidmap_lock is held as an
@ -192,8 +202,7 @@ fastcall void put_pid(struct pid *pid)
if ((atomic_read(&pid->count) == 1) ||
atomic_dec_and_test(&pid->count)) {
kmem_cache_free(ns->pid_cachep, pid);
if (ns != &init_pid_ns)
put_pid_ns(ns);
put_pid_ns(ns);
}
}
EXPORT_SYMBOL_GPL(put_pid);
@ -244,9 +253,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
tmp = tmp->parent;
}
if (ns != &init_pid_ns)
get_pid_ns(ns);
get_pid_ns(ns);
pid->level = ns->level;
pid->nr = pid->numbers[0].nr;
atomic_set(&pid->count, 1);