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, 4 insertions, 22 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 07f4b7abc80a..fe92471e19c7 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -56,9 +56,7 @@ struct shm_file_data {
 static const struct file_operations shm_file_operations;
 static struct vm_operations_struct shm_vm_ops;
 
-static struct ipc_ids init_shm_ids;
-
-#define shm_ids(ns)     (*((ns)->ids[IPC_SHM_IDS]))
+#define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
 
 #define shm_unlock(shp)                 \
         ipc_unlock(&(shp)->shm_perm)
@@ -72,14 +70,13 @@ static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
 #endif
 
-static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
+void shm_init_ns(struct ipc_namespace *ns)
 {
-        ns->ids[IPC_SHM_IDS] = ids;
         ns->shm_ctlmax = SHMMAX;
         ns->shm_ctlall = SHMALL;
         ns->shm_ctlmni = SHMMNI;
         ns->shm_tot = 0;
-        ipc_init_ids(ids);
+        ipc_init_ids(&ns->ids[IPC_SHM_IDS]);
 }
 
 /*
@@ -98,18 +95,6 @@ static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
 }
 
 #ifdef CONFIG_IPC_NS
-int shm_init_ns(struct ipc_namespace *ns)
-{
-        struct ipc_ids *ids;
-
-        ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
-        if (ids == NULL)
-                return -ENOMEM;
-
-        __shm_init_ns(ns, ids);
-        return 0;
-}
-
 void shm_exit_ns(struct ipc_namespace *ns)
 {
         struct shmid_kernel *shp;
@@ -131,15 +116,12 @@ void shm_exit_ns(struct ipc_namespace *ns)
                 total++;
         }
         up_write(&shm_ids(ns).rw_mutex);
-
-        kfree(ns->ids[IPC_SHM_IDS]);
-        ns->ids[IPC_SHM_IDS] = NULL;
 }
 #endif
 
 void __init shm_init (void)
 {
-        __shm_init_ns(&init_ipc_ns, &init_shm_ids);
+        shm_init_ns(&init_ipc_ns);
         ipc_init_proc_interface("sysvipc/shm",
                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
                                 IPC_SHM_IDS, sysvipc_shm_proc_show);