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ipc: recompute msgmni on ipc namespace creation/removal

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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>
This commit is contained in:
Nadia Derbey 2008-04-29 01:00:44 -07:00 committed by Linus Torvalds
parent 424450c1db
commit e2c284d8a8
4 changed files with 17 additions and 25 deletions
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25
include/linux/ipc_namespace.h
View File

@ -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 */

3
ipc/Makefile
View File

@ -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)

2
ipc/ipcns_notifier.c
View File

@ -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
*/

12
ipc/namespace.c
View File

@ -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);
}