IPC: make struct ipc_ids static in ipc_namespace

Each ipc_namespace contains a table of 3 pointers to struct ipc_ids (3 for
msg, sem and shm, structure used to store all ipcs) These 'struct ipc_ids'
are dynamically allocated for each icp_namespace as the ipc_namespace
itself (for the init namespace, they are initialized with pointers to
static variables instead)

It is so for historical reason: in fact, before the use of idr to store the
ipcs, the ipcs were stored in tables of variable length, depending of the
maximum number of ipc allowed.  Now, these 'struct ipc_ids' have a fixed
size.  As they are allocated in any cases for each new ipc_namespace, there
is no gain of memory in having them allocated separately of the struct
ipc_namespace.

This patch proposes to make this table static in the struct ipc_namespace.
Thus, we can allocate all in once and get rid of all the code needed to
allocate and free these ipc_ids separately.

Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Acked-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index a491fc9dd231..6db5522eef51 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -2,11 +2,20 @@
 #define __IPC_NAMESPACE_H__
 
 #include <linux/err.h>
+#include <linux/idr.h>
+#include <linux/rwsem.h>
+
+struct ipc_ids {
+        int in_use;
+        unsigned short seq;
+        unsigned short seq_max;
+        struct rw_semaphore rw_mutex;
+        struct idr ipcs_idr;
+};
 
-struct ipc_ids;
 struct ipc_namespace {
         struct kref     kref;
-        struct ipc_ids  *ids[3];
+        struct ipc_ids  ids[3];
 
         int             sem_ctls[4];
         int             used_sems;