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>

1 files changed, 2 insertions, 0 deletions

diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
index 0786af6ce3ec..c7974609defc 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
                  */