/*
   * linux/ipc/namespace.c
   * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
   */
  
  #include <linux/ipc.h>
  #include <linux/msg.h>
  #include <linux/ipc_namespace.h>
  #include <linux/rcupdate.h>
  #include <linux/nsproxy.h>
  #include <linux/slab.h>
  
  #include "util.h"
  
  static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
  {

  	struct ipc_namespace *ns;

  	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
  	if (ns == NULL)

  		return ERR_PTR(-ENOMEM);

  	atomic_inc(&nr_ipc_ns);

  	sem_init_ns(ns);
  	msg_init_ns(ns);
  	shm_init_ns(ns);

  	/*
  	 * msgmni has already been computed for the new ipc ns.
  	 * Thus, do the ipcns creation notification before registering that
  	 * new ipcns in the chain.
  	 */
  	ipcns_notify(IPCNS_CREATED);

  	register_ipcns_notifier(ns);

  	kref_init(&ns->kref);
  	return ns;

  }
  
  struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
  {
  	struct ipc_namespace *new_ns;
  
  	BUG_ON(!ns);
  	get_ipc_ns(ns);
  
  	if (!(flags & CLONE_NEWIPC))
  		return ns;
  
  	new_ns = clone_ipc_ns(ns);
  
  	put_ipc_ns(ns);
  	return new_ns;
  }

  /*
   * free_ipcs - free all ipcs of one type
   * @ns:   the namespace to remove the ipcs from
   * @ids:  the table of ipcs to free
   * @free: the function called to free each individual ipc
   *
   * Called for each kind of ipc when an ipc_namespace exits.
   */
  void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
  	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
  {
  	struct kern_ipc_perm *perm;
  	int next_id;
  	int total, in_use;
  
  	down_write(&ids->rw_mutex);
  
  	in_use = ids->in_use;
  
  	for (total = 0, next_id = 0; total < in_use; next_id++) {
  		perm = idr_find(&ids->ipcs_idr, next_id);
  		if (perm == NULL)
  			continue;
  		ipc_lock_by_ptr(perm);
  		free(ns, perm);
  		total++;
  	}
  	up_write(&ids->rw_mutex);
  }

  void free_ipc_ns(struct kref *kref)
  {
  	struct ipc_namespace *ns;
  
  	ns = container_of(kref, struct ipc_namespace, kref);

  	/*
  	 * Unregistering the hotplug notifier at the beginning guarantees
  	 * that the ipc namespace won't be freed while we are inside the
  	 * callback routine. Since the blocking_notifier_chain_XXX routines
  	 * hold a rw lock on the notifier list, unregister_ipcns_notifier()
  	 * won't take the rw lock before blocking_notifier_call_chain() has
  	 * released the rd lock.
  	 */
  	unregister_ipcns_notifier(ns);

  	sem_exit_ns(ns);
  	msg_exit_ns(ns);
  	shm_exit_ns(ns);
  	kfree(ns);

  	atomic_dec(&nr_ipc_ns);

  
  	/*
  	 * Do the ipcns removal notification after decrementing nr_ipc_ns in
  	 * order to have a correct value when recomputing msgmni.
  	 */
  	ipcns_notify(IPCNS_REMOVED);

  }