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-rw-r--r--ipc/util.c33
1 files changed, 33 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c
index c27f0e92f489..2d545d7144a7 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -33,6 +33,7 @@
#include <linux/audit.h>
#include <linux/nsproxy.h>
#include <linux/rwsem.h>
+#include <linux/memory.h>
#include <linux/ipc_namespace.h>
#include <asm/unistd.h>
@@ -55,11 +56,41 @@ struct ipc_namespace init_ipc_ns = {
atomic_t nr_ipc_ns = ATOMIC_INIT(1);
+#ifdef CONFIG_MEMORY_HOTPLUG
+
+static int ipc_memory_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ switch (action) {
+ case MEM_ONLINE: /* memory successfully brought online */
+ case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
+ /*
+ * This is done by invoking the ipcns notifier chain with the
+ * IPC_MEMCHANGED event.
+ */
+ ipcns_notify(IPCNS_MEMCHANGED);
+ break;
+ case MEM_GOING_ONLINE:
+ case MEM_GOING_OFFLINE:
+ case MEM_CANCEL_ONLINE:
+ case MEM_CANCEL_OFFLINE:
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
/**
* ipc_init - initialise IPC subsystem
*
* The various system5 IPC resources (semaphores, messages and shared
* memory) are initialised
+ * A callback routine is registered into the memory hotplug notifier
+ * chain: since msgmni scales to lowmem this callback routine will be
+ * called upon successful memory add / remove to recompute msmgni.
*/
static int __init ipc_init(void)
@@ -67,6 +98,8 @@ static int __init ipc_init(void)
sem_init();
msg_init();
shm_init();
+ hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
+ register_ipcns_notifier(&init_ipc_ns);
return 0;
}
__initcall(ipc_init);

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