Commit b6b337ad authored by Nadia Derbey's avatar Nadia Derbey Committed by Linus Torvalds
Browse files

ipc: recompute msgmni on memory add / remove 



Introduce the registration of a callback routine that recomputes msg_ctlmni
upon memory add / remove.

A single notifier block is registered in the hotplug memory chain for all the
ipc namespaces.

Since the ipc namespaces are not linked together, they have their own
notification chain: one notifier_block is defined per ipc namespace.

Each time an ipc namespace is created (removed) it registers (unregisters) its
notifier block in (from) the ipcns chain.  The callback routine registered in
the memory chain invokes the ipcns notifier chain with the IPCNS_LOWMEM event.
 Each callback routine registered in the ipcns namespace, in turn, recomputes
msgmni for the owning namespace.

Signed-off-by: default avatarNadia 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0c40ba4f

include/linux/ipc_namespace.h

+41 −2
Original line number Diff line number Diff line
@@ -4,6 +4,17 @@ 
#include <linux/err.h>

#include <linux/idr.h>

#include <linux/rwsem.h>

#ifdef CONFIG_MEMORY_HOTPLUG

#include <linux/notifier.h>

#endif /* CONFIG_MEMORY_HOTPLUG */



/*

 * ipc namespace events

 */

#define IPCNS_MEMCHANGED   0x00000001   /* Notify lowmem size changed */



#define IPCNS_CALLBACK_PRI 0





struct ipc_ids {

	int in_use;
@@ -30,6 +41,10 @@ struct ipc_namespace { 
	size_t		shm_ctlall;

	int		shm_ctlmni;

	int		shm_tot;



#ifdef CONFIG_MEMORY_HOTPLUG

	struct notifier_block ipcns_nb;

#endif

};



extern struct ipc_namespace init_ipc_ns;
@@ -37,9 +52,33 @@ extern atomic_t nr_ipc_ns; 


#ifdef CONFIG_SYSVIPC

#define INIT_IPC_NS(ns)		.ns		= &init_ipc_ns,

#else



#ifdef CONFIG_MEMORY_HOTPLUG



extern int register_ipcns_notifier(struct ipc_namespace *);

extern int unregister_ipcns_notifier(struct ipc_namespace *);

extern int ipcns_notify(unsigned long);



#else /* CONFIG_MEMORY_HOTPLUG */



static inline int register_ipcns_notifier(struct ipc_namespace *ipcns)

{

	return 0;

}

static inline int unregister_ipcns_notifier(struct ipc_namespace *ipcns)

{

	return 0;

}

static inline int ipcns_notify(unsigned long ev)

{

	return 0;

}



#endif /* CONFIG_MEMORY_HOTPLUG */



#else /* CONFIG_SYSVIPC */

#define INIT_IPC_NS(ns)

#endif

#endif /* CONFIG_SYSVIPC */



#if defined(CONFIG_SYSVIPC) && defined(CONFIG_IPC_NS)

extern void free_ipc_ns(struct kref *kref);

include/linux/memory.h

+1 −0
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ struct mem_section; 
 * order in the callback chain)

 */

#define SLAB_CALLBACK_PRI       1

#define IPC_CALLBACK_PRI        10



#ifndef CONFIG_MEMORY_HOTPLUG_SPARSE

static inline int memory_dev_init(void)

ipc/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -3,7 +3,8 @@ 
#



obj-$(CONFIG_SYSVIPC_COMPAT) += compat.o

obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o

obj_mem-$(CONFIG_MEMORY_HOTPLUG) += ipcns_notifier.o

obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o $(obj_mem-y)

obj-$(CONFIG_SYSVIPC_SYSCTL) += ipc_sysctl.o

obj_mq-$(CONFIG_COMPAT) += compat_mq.o

obj-$(CONFIG_POSIX_MQUEUE) += mqueue.o msgutil.o $(obj_mq-y)

ipc/ipcns_notifier.c

0 → 100644
+71 −0
Original line number Diff line number Diff line 
/*

 * linux/ipc/ipcns_notifier.c

 * Copyright (C) 2007 BULL SA. Nadia Derbey

 *

 * Notification mechanism for ipc namespaces:

 * The callback routine registered in the memory chain invokes the ipcns

 * notifier chain with the IPCNS_MEMCHANGED event.

 * Each callback routine registered in the ipcns namespace recomputes msgmni

 * for the owning namespace.

 */



#include <linux/msg.h>

#include <linux/rcupdate.h>

#include <linux/notifier.h>

#include <linux/nsproxy.h>

#include <linux/ipc_namespace.h>



#include "util.h"







static BLOCKING_NOTIFIER_HEAD(ipcns_chain);





static int ipcns_callback(struct notifier_block *self,

				unsigned long action, void *arg)

{

	struct ipc_namespace *ns;



	switch (action) {

	case IPCNS_MEMCHANGED:   /* amount of lowmem has changed */

		/*

		 * It's time to recompute msgmni

		 */

		ns = container_of(self, struct ipc_namespace, ipcns_nb);

		/*

		 * No need to get a reference on the ns: the 1st job of

		 * free_ipc_ns() is to unregister the callback routine.

		 * blocking_notifier_chain_unregister takes the wr lock to do

		 * it.

		 * When this callback routine is called the rd lock is held by

		 * blocking_notifier_call_chain.

		 * So the ipc ns cannot be freed while we are here.

		 */

		recompute_msgmni(ns);

		break;

	default:

		break;

	}



	return NOTIFY_OK;

}



int register_ipcns_notifier(struct ipc_namespace *ns)

{

	memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));

	ns->ipcns_nb.notifier_call = ipcns_callback;

	ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;

	return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);

}



int unregister_ipcns_notifier(struct ipc_namespace *ns)

{

	return blocking_notifier_chain_unregister(&ipcns_chain,

						&ns->ipcns_nb);

}



int ipcns_notify(unsigned long val)

{

	return blocking_notifier_call_chain(&ipcns_chain, val, NULL);

}

ipc/msg.c

+1 −1
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it); 
 * Also take into account the number of nsproxies created so far.

 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.

 */

static void recompute_msgmni(struct ipc_namespace *ns)

void recompute_msgmni(struct ipc_namespace *ns)

{

	struct sysinfo i;

	unsigned long allowed;

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