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With multiple pid namespaces, a process is known by some pid_t in every ancestor pid namespace. Every time the process forks, the child process also gets a pid_t in every ancestor pid namespace. While a process is visible in >=1 pid namespaces, it can see pid_t's in only one pid namespace. We call this pid namespace it's "active pid namespace", and it is always the youngest pid namespace in which the process is known. This patch defines and uses a wrapper to find the active pid namespace of a process. The implementation of the wrapper will be changed in when support for multiple pid namespaces are added. Changelog: 2.6.22-rc4-mm2-pidns1: - [Pavel Emelianov, Alexey Dobriyan] Back out the change to use task_active_pid_ns() in child_reaper() since task->nsproxy can be NULL during task exit (so child_reaper() continues to use init_pid_ns). to implement child_reaper() since init_pid_ns.child_reaper to implement child_reaper() since tsk->nsproxy can be NULL during exit. 2.6.21-rc6-mm1: - Rename task_pid_ns() to task_active_pid_ns() to reflect that a process can have multiple pid namespaces. Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Acked-by: Pavel Emelianov <xemul@openvz.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Serge Hallyn <serue@us.ibm.com> Cc: Herbert Poetzel <herbert@13thfloor.at> Cc: Kirill Korotaev <dev@sw.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
#ifndef _LINUX_PID_NS_H
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#define _LINUX_PID_NS_H
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/threads.h>
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#include <linux/pid.h>
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#include <linux/nsproxy.h>
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#include <linux/kref.h>
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struct pidmap {
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atomic_t nr_free;
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void *page;
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};
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#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)
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struct pid_namespace {
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struct kref kref;
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struct pidmap pidmap[PIDMAP_ENTRIES];
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int last_pid;
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struct task_struct *child_reaper;
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struct kmem_cache *pid_cachep;
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};
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extern struct pid_namespace init_pid_ns;
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static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
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{
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kref_get(&ns->kref);
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return ns;
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}
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extern struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *ns);
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extern void free_pid_ns(struct kref *kref);
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static inline void put_pid_ns(struct pid_namespace *ns)
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{
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kref_put(&ns->kref, free_pid_ns);
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}
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static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
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{
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return tsk->nsproxy->pid_ns;
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}
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static inline struct task_struct *child_reaper(struct task_struct *tsk)
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{
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return init_pid_ns.child_reaper;
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}
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#endif /* _LINUX_PID_NS_H */
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