aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--include/linux/ipc_namespace.h43
-rw-r--r--include/linux/memory.h1
-rw-r--r--ipc/Makefile3
-rw-r--r--ipc/ipcns_notifier.c71
-rw-r--r--ipc/msg.c2
-rw-r--r--ipc/namespace.c11
-rw-r--r--ipc/util.c33
-rw-r--r--ipc/util.h2
8 files changed, 162 insertions, 4 deletions
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 878d7ac286f..cfb2a08b28f 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -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);
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 39628dfe4a4..2f5f8a5ef2a 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -58,6 +58,7 @@ struct mem_section;
* order in the callback chain)
*/
#define SLAB_CALLBACK_PRI 1
+#define IPC_CALLBACK_PRI 10
#ifndef CONFIG_MEMORY_HOTPLUG_SPARSE
static inline int memory_dev_init(void)
diff --git a/ipc/Makefile b/ipc/Makefile
index 5fc5e33ea04..388e4d259f0 100644
--- a/ipc/Makefile
+++ b/ipc/Makefile
@@ -3,7 +3,8 @@
#
obj-$(CONFIG_SYSVIPC_COMPAT) += compat.o
-obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.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_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
new file mode 100644
index 00000000000..0786af6ce3e
--- /dev/null
+++ b/ipc/ipcns_notifier.c
@@ -0,0 +1,71 @@
+/*
+ * linux/ipc/ipcns_notifier.c
+ * Copyright (C) 2007 BULL SA. Nadia Derbey
+ *
+ * Notification mechanism for ipc namespaces:
+ * The callback routine registered in the memory chain invokes the ipcns
+ * notifier chain with the IPCNS_MEMCHANGED event.
+ * Each callback routine registered in the ipcns namespace recomputes msgmni
+ * for the owning namespace.
+ */
+
+#include <linux/msg.h>
+#include <linux/rcupdate.h>
+#include <linux/notifier.h>
+#include <linux/nsproxy.h>
+#include <linux/ipc_namespace.h>
+
+#include "util.h"
+
+
+
+static BLOCKING_NOTIFIER_HEAD(ipcns_chain);
+
+
+static int ipcns_callback(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ struct ipc_namespace *ns;
+
+ switch (action) {
+ case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
+ /*
+ * It's time to recompute msgmni
+ */
+ ns = container_of(self, struct ipc_namespace, ipcns_nb);
+ /*
+ * No need to get a reference on the ns: the 1st job of
+ * free_ipc_ns() is to unregister the callback routine.
+ * blocking_notifier_chain_unregister takes the wr lock to do
+ * it.
+ * When this callback routine is called the rd lock is held by
+ * blocking_notifier_call_chain.
+ * So the ipc ns cannot be freed while we are here.
+ */
+ recompute_msgmni(ns);
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+int register_ipcns_notifier(struct ipc_namespace *ns)
+{
+ memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
+ ns->ipcns_nb.notifier_call = ipcns_callback;
+ ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
+ return blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
+}
+
+int unregister_ipcns_notifier(struct ipc_namespace *ns)
+{
+ return blocking_notifier_chain_unregister(&ipcns_chain,
+ &ns->ipcns_nb);
+}
+
+int ipcns_notify(unsigned long val)
+{
+ return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
+}
diff --git a/ipc/msg.c b/ipc/msg.c
index be8449d48a8..7d9b0694c74 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -84,7 +84,7 @@ static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
* Also take into account the number of nsproxies created so far.
* This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
*/
-static void recompute_msgmni(struct ipc_namespace *ns)
+void recompute_msgmni(struct ipc_namespace *ns)
{
struct sysinfo i;
unsigned long allowed;
diff --git a/ipc/namespace.c b/ipc/namespace.c
index fe3c97aa99d..f7a35be2e77 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -26,6 +26,8 @@ static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
msg_init_ns(ns);
shm_init_ns(ns);
+ register_ipcns_notifier(ns);
+
kref_init(&ns->kref);
return ns;
}
@@ -81,6 +83,15 @@ void free_ipc_ns(struct kref *kref)
struct ipc_namespace *ns;
ns = container_of(kref, struct ipc_namespace, kref);
+ /*
+ * Unregistering the hotplug notifier at the beginning guarantees
+ * that the ipc namespace won't be freed while we are inside the
+ * callback routine. Since the blocking_notifier_chain_XXX routines
+ * hold a rw lock on the notifier list, unregister_ipcns_notifier()
+ * won't take the rw lock before blocking_notifier_call_chain() has
+ * released the rd lock.
+ */
+ unregister_ipcns_notifier(ns);
sem_exit_ns(ns);
msg_exit_ns(ns);
shm_exit_ns(ns);
diff --git a/ipc/util.c b/ipc/util.c
index c27f0e92f48..2d545d7144a 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);
diff --git a/ipc/util.h b/ipc/util.h
index f37d160c98f..0e3d79037a2 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -124,6 +124,8 @@ extern void free_msg(struct msg_msg *msg);
extern struct msg_msg *load_msg(const void __user *src, int len);
extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
+extern void recompute_msgmni(struct ipc_namespace *);
+
static inline int ipc_buildid(int id, int seq)
{
return SEQ_MULTIPLIER * seq + id;