ipc: recompute msgmni on ipc namespace creation/removal

e2c284d8 · Nadia Derbey <[email protected]> · 2008-04-29 01:00:44 -07:00

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 <[email protected]>
Cc: Yasunori Goto <[email protected]>
Cc: Matt Helsley <[email protected]>
Cc: Mingming Cao <[email protected]>
Cc: Pierre Peiffer <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: e2c284d8a87f95df9b47c6a13168a844ca7c03e9
Parents: 424450c1

Changes

4 files changed · +17 −25

File	Status	Add	Del	Content
include/linux/ipc_namespace.h	modified	+2	−23	View file
ipc/Makefile	modified	+1	−2	View file
ipc/ipcns_notifier.c	modified	+2	−0	View file
ipc/namespace.c	modified	+12	−0	View file

include/linux/ipc_namespace.h

View file

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index cfb2a08..c3b1da9 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -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

View file

diff --git a/ipc/Makefile b/ipc/Makefile
index 388e4d2..65c3843 100644
--- a/ipc/Makefile
+++ b/ipc/Makefile
@@ -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

View file

diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
index 0786af6..c797460 100644
--- a/ipc/ipcns_notifier.c
+++ b/ipc/ipcns_notifier.c
@@ -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

View file

diff --git a/ipc/namespace.c b/ipc/namespace.c
index f7a35be..9171d94 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -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);
 }