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ipc: recompute msgmni on memory add / remove

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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: 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 01:00:42 -07:00 • committed by Linus Torvalds
parent 0c40ba4fd6
commit b6b337ad1c
8 changed files with 162 additions and 4 deletions
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43
include/linux/ipc_namespace.h
View file

@ -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);