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Commit e2c284d8 authored by Nadia Derbey's avatar Nadia Derbey Committed by Linus Torvalds
Browse files

ipc: recompute msgmni on ipc namespace creation/removal 



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: 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 424450c1

include/linux/ipc_namespace.h

+2 −23
Original line number Diff line number Diff line
@@ -4,14 +4,14 @@ 
#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_CREATED  0x00000002   /* Notify new ipc namespace created */

#define IPCNS_REMOVED  0x00000003   /* Notify ipc namespace removed */



#define IPCNS_CALLBACK_PRI 0
@@ -42,9 +42,7 @@ struct ipc_namespace { 
	int		shm_ctlmni;

	int		shm_tot;



#ifdef CONFIG_MEMORY_HOTPLUG

	struct notifier_block ipcns_nb;

#endif

};



extern struct ipc_namespace init_ipc_ns;
@@ -53,29 +51,10 @@ extern atomic_t nr_ipc_ns; 
#ifdef CONFIG_SYSVIPC

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



#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 /* CONFIG_SYSVIPC */

ipc/Makefile

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



obj-$(CONFIG_SYSVIPC_COMPAT) += compat.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) += util.o msgutil.o msg.o sem.o shm.o ipcns_notifier.o

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

+2 −0
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ static int ipcns_callback(struct notifier_block *self, 


	switch (action) {

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

	case IPCNS_CREATED:

	case IPCNS_REMOVED:

		/*

		 * It's time to recompute msgmni

		 */

ipc/namespace.c

+12 −0
Original line number Diff line number Diff line
@@ -26,6 +26,12 @@ static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_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);
@@ -97,4 +103,10 @@ void free_ipc_ns(struct kref *kref) 
	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);

}