linux-stable/include/linux/nsproxy.h
Daniel Lezcano a77aea9201 cgroup: remove the ns_cgroup
The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and
leads to some problems:

  * cgroup creation is out-of-control
  * cgroup name can conflict when pids are looping
  * it is not possible to have a single process handling a lot of
    namespaces without falling in a exponential creation time
  * we may want to create a namespace without creating a cgroup

  The ns_cgroup was replaced by a compatibility flag 'clone_children',
  where a newly created cgroup will copy the parent cgroup values.
  The userspace has to manually create a cgroup and add a task to
  the 'tasks' file.

This patch removes the ns_cgroup as suggested in the following thread:

https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html

The 'cgroup_clone' function is removed because it is no longer used.

This is a userspace-visible change.  Commit 45531757b4 ("cgroup: notify
ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a
printk warning users that the feature is planned for removal.  Since that
time we have heard from XXX users who were affected by this.

Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jamal Hadi Salim <hadi@cyberus.ca>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-26 17:12:34 -07:00

84 lines
2.2 KiB
C

#ifndef _LINUX_NSPROXY_H
#define _LINUX_NSPROXY_H
#include <linux/spinlock.h>
#include <linux/sched.h>
struct mnt_namespace;
struct uts_namespace;
struct ipc_namespace;
struct pid_namespace;
struct fs_struct;
/*
* A structure to contain pointers to all per-process
* namespaces - fs (mount), uts, network, sysvipc, etc.
*
* 'count' is the number of tasks holding a reference.
* The count for each namespace, then, will be the number
* of nsproxies pointing to it, not the number of tasks.
*
* The nsproxy is shared by tasks which share all namespaces.
* As soon as a single namespace is cloned or unshared, the
* nsproxy is copied.
*/
struct nsproxy {
atomic_t count;
struct uts_namespace *uts_ns;
struct ipc_namespace *ipc_ns;
struct mnt_namespace *mnt_ns;
struct pid_namespace *pid_ns;
struct net *net_ns;
};
extern struct nsproxy init_nsproxy;
/*
* the namespaces access rules are:
*
* 1. only current task is allowed to change tsk->nsproxy pointer or
* any pointer on the nsproxy itself
*
* 2. when accessing (i.e. reading) current task's namespaces - no
* precautions should be taken - just dereference the pointers
*
* 3. the access to other task namespaces is performed like this
* rcu_read_lock();
* nsproxy = task_nsproxy(tsk);
* if (nsproxy != NULL) {
* / *
* * work with the namespaces here
* * e.g. get the reference on one of them
* * /
* } / *
* * NULL task_nsproxy() means that this task is
* * almost dead (zombie)
* * /
* rcu_read_unlock();
*
*/
static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
{
return rcu_dereference(tsk->nsproxy);
}
int copy_namespaces(unsigned long flags, struct task_struct *tsk);
void exit_task_namespaces(struct task_struct *tsk);
void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
void free_nsproxy(struct nsproxy *ns);
int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
struct fs_struct *);
static inline void put_nsproxy(struct nsproxy *ns)
{
if (atomic_dec_and_test(&ns->count)) {
free_nsproxy(ns);
}
}
static inline void get_nsproxy(struct nsproxy *ns)
{
atomic_inc(&ns->count);
}
#endif