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e2c284d8a8
Introduce a notification mechanism that aims at recomputing msgmni each time an ipc namespace is created or removed. The ipc namespace notifier chain already defined for memory hotplug management is used for that purpose too. Each time a new ipc namespace is allocated or an existing ipc namespace is removed, the ipcns notifier chain is notified. The callback routine for each registered ipc namespace is then activated in order to recompute msgmni for that namespace. Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Mingming Cao <cmm@us.ibm.com> Cc: Pierre Peiffer <pierre.peiffer@bull.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/*
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* linux/ipc/namespace.c
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* Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
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*/
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#include <linux/ipc.h>
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#include <linux/msg.h>
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#include <linux/ipc_namespace.h>
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#include <linux/rcupdate.h>
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#include <linux/nsproxy.h>
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#include <linux/slab.h>
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#include "util.h"
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static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
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{
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struct ipc_namespace *ns;
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ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
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if (ns == NULL)
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return ERR_PTR(-ENOMEM);
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atomic_inc(&nr_ipc_ns);
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sem_init_ns(ns);
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msg_init_ns(ns);
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shm_init_ns(ns);
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/*
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* msgmni has already been computed for the new ipc ns.
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* Thus, do the ipcns creation notification before registering that
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* new ipcns in the chain.
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*/
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ipcns_notify(IPCNS_CREATED);
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register_ipcns_notifier(ns);
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kref_init(&ns->kref);
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return ns;
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}
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struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
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{
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struct ipc_namespace *new_ns;
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BUG_ON(!ns);
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get_ipc_ns(ns);
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if (!(flags & CLONE_NEWIPC))
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return ns;
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new_ns = clone_ipc_ns(ns);
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put_ipc_ns(ns);
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return new_ns;
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}
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/*
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* free_ipcs - free all ipcs of one type
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* @ns: the namespace to remove the ipcs from
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* @ids: the table of ipcs to free
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* @free: the function called to free each individual ipc
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*
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* Called for each kind of ipc when an ipc_namespace exits.
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*/
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void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
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void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
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{
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struct kern_ipc_perm *perm;
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int next_id;
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int total, in_use;
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down_write(&ids->rw_mutex);
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in_use = ids->in_use;
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for (total = 0, next_id = 0; total < in_use; next_id++) {
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perm = idr_find(&ids->ipcs_idr, next_id);
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if (perm == NULL)
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continue;
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ipc_lock_by_ptr(perm);
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free(ns, perm);
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total++;
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}
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up_write(&ids->rw_mutex);
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}
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void free_ipc_ns(struct kref *kref)
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{
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struct ipc_namespace *ns;
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ns = container_of(kref, struct ipc_namespace, kref);
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/*
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* Unregistering the hotplug notifier at the beginning guarantees
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* that the ipc namespace won't be freed while we are inside the
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* callback routine. Since the blocking_notifier_chain_XXX routines
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* hold a rw lock on the notifier list, unregister_ipcns_notifier()
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* won't take the rw lock before blocking_notifier_call_chain() has
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* released the rd lock.
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*/
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unregister_ipcns_notifier(ns);
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sem_exit_ns(ns);
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msg_exit_ns(ns);
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shm_exit_ns(ns);
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kfree(ns);
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atomic_dec(&nr_ipc_ns);
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/*
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* Do the ipcns removal notification after decrementing nr_ipc_ns in
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* order to have a correct value when recomputing msgmni.
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*/
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ipcns_notify(IPCNS_REMOVED);
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}
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