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authorNadia Derbey <Nadia.Derbey@bull.net>2008-04-29 01:00:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:12 -0700
commite2c284d8a87f95df9b47c6a13168a844ca7c03e9 (patch)
tree6eb27ea254d47c94dbfb33da23314dd69479e56e
parent424450c1dbe72b6e2637e91108417d7d9580c4c3 (diff)
downloadlinux-linaro-precise-e2c284d8a87f95df9b47c6a13168a844ca7c03e9.tar.gz
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: 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>
-rw-r--r--include/linux/ipc_namespace.h25
-rw-r--r--ipc/Makefile3
-rw-r--r--ipc/ipcns_notifier.c2
-rw-r--r--ipc/namespace.c12
4 files changed, 17 insertions, 25 deletions
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index cfb2a08b28f..c3b1da9e5fe 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 */
diff --git a/ipc/Makefile b/ipc/Makefile
index 388e4d259f0..65c38439580 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)
diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
index 0786af6ce3e..c7974609def 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
*/
diff --git a/ipc/namespace.c b/ipc/namespace.c
index f7a35be2e77..9171d948751 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);
}