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>
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
/*
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* linux/ipc/ipcns_notifier.c
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* Copyright (C) 2007 BULL SA. Nadia Derbey
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*
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* Notification mechanism for ipc namespaces:
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* The callback routine registered in the memory chain invokes the ipcns
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* notifier chain with the IPCNS_MEMCHANGED event.
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* Each callback routine registered in the ipcns namespace recomputes msgmni
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* for the owning namespace.
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*/
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#include <linux/msg.h>
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#include <linux/rcupdate.h>
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#include <linux/notifier.h>
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#include <linux/nsproxy.h>
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#include <linux/ipc_namespace.h>
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#include "util.h"
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static BLOCKING_NOTIFIER_HEAD(ipcns_chain);
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static int ipcns_callback(struct notifier_block *self,
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unsigned long action, void *arg)
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{
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struct ipc_namespace *ns;
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switch (action) {
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case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
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case IPCNS_CREATED:
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case IPCNS_REMOVED:
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/*
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* It's time to recompute msgmni
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*/
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ns = container_of(self, struct ipc_namespace, ipcns_nb);
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/*
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* No need to get a reference on the ns: the 1st job of
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* free_ipc_ns() is to unregister the callback routine.
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* blocking_notifier_chain_unregister takes the wr lock to do
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* it.
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* When this callback routine is called the rd lock is held by
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* blocking_notifier_call_chain.
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* So the ipc ns cannot be freed while we are here.
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*/
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recompute_msgmni(ns);
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break;
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default:
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break;
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}
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return NOTIFY_OK;
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}
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int register_ipcns_notifier(struct ipc_namespace *ns)
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{
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memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
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ns->ipcns_nb.notifier_call = ipcns_callback;
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ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
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return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
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}
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int unregister_ipcns_notifier(struct ipc_namespace *ns)
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{
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return blocking_notifier_chain_unregister(&ipcns_chain,
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&ns->ipcns_nb);
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}
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int ipcns_notify(unsigned long val)
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{
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return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
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}
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