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>

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;

ipc/msg.c

@@ -67,9 +67,7 @@ struct msg_sender {
 #define SEARCH_NOTEQUAL		3
 #define SEARCH_LESSEQUAL	4
 
-static struct ipc_ids init_msg_ids;
-
-#define msg_ids(ns)	(*((ns)->ids[IPC_MSG_IDS]))
+#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
 
 #define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
 #define msg_buildid(id, seq)	ipc_buildid(id, seq)
@@ -80,30 +78,17 @@ static int newque(struct ipc_namespace *, struct ipc_params *);
 static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
 #endif
 
-static void __msg_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
+void msg_init_ns(struct ipc_namespace *ns)
 {
-	ns->ids[IPC_MSG_IDS] = ids;
 	ns->msg_ctlmax = MSGMAX;
 	ns->msg_ctlmnb = MSGMNB;
 	ns->msg_ctlmni = MSGMNI;
 	atomic_set(&ns->msg_bytes, 0);
 	atomic_set(&ns->msg_hdrs, 0);
-	ipc_init_ids(ids);
+	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
 }
 
 #ifdef CONFIG_IPC_NS
-int msg_init_ns(struct ipc_namespace *ns)
-{
-	struct ipc_ids *ids;
-
-	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
-	if (ids == NULL)
-		return -ENOMEM;
-
-	__msg_init_ns(ns, ids);
-	return 0;
-}
-
 void msg_exit_ns(struct ipc_namespace *ns)
 {
 	struct msg_queue *msq;
@@ -126,15 +111,12 @@ void msg_exit_ns(struct ipc_namespace *ns)
 	}
 
 	up_write(&msg_ids(ns).rw_mutex);
-
-	kfree(ns->ids[IPC_MSG_IDS]);
-	ns->ids[IPC_MSG_IDS] = NULL;
 }
 #endif
 
 void __init msg_init(void)
 {
-	__msg_init_ns(&init_ipc_ns, &init_msg_ids);
+	msg_init_ns(&init_ipc_ns);
 	ipc_init_proc_interface("sysvipc/msg",
 				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
 				IPC_MSG_IDS, sysvipc_msg_proc_show);

ipc/namespace.c

@@ -14,35 +14,18 @@
 
 static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
 {
-	int err;
 	struct ipc_namespace *ns;
 
-	err = -ENOMEM;
 	ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
 	if (ns == NULL)
-		goto err_mem;
+		return ERR_PTR(-ENOMEM);
 
-	err = sem_init_ns(ns);
-	if (err)
-		goto err_sem;
-	err = msg_init_ns(ns);
-	if (err)
-		goto err_msg;
-	err = shm_init_ns(ns);
-	if (err)
-		goto err_shm;
+	sem_init_ns(ns);
+	msg_init_ns(ns);
+	shm_init_ns(ns);
 
 	kref_init(&ns->kref);
 	return ns;
-
-err_shm:
-	msg_exit_ns(ns);
-err_msg:
-	sem_exit_ns(ns);
-err_sem:
-	kfree(ns);
-err_mem:
-	return ERR_PTR(err);
 }
 
 struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)

ipc/sem.c

@@ -87,14 +87,12 @@
 #include <asm/uaccess.h>
 #include "util.h"
 
-#define sem_ids(ns)	(*((ns)->ids[IPC_SEM_IDS]))
+#define sem_ids(ns)	((ns)->ids[IPC_SEM_IDS])
 
 #define sem_unlock(sma)		ipc_unlock(&(sma)->sem_perm)
 #define sem_checkid(sma, semid)	ipc_checkid(&sma->sem_perm, semid)
 #define sem_buildid(id, seq)	ipc_buildid(id, seq)
 
-static struct ipc_ids init_sem_ids;
-
 static int newary(struct ipc_namespace *, struct ipc_params *);
 static void freeary(struct ipc_namespace *, struct sem_array *);
 #ifdef CONFIG_PROC_FS
@@ -118,30 +116,17 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
 #define sc_semopm	sem_ctls[2]
 #define sc_semmni	sem_ctls[3]
 
-static void __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
+void sem_init_ns(struct ipc_namespace *ns)
 {
-	ns->ids[IPC_SEM_IDS] = ids;
 	ns->sc_semmsl = SEMMSL;
 	ns->sc_semmns = SEMMNS;
 	ns->sc_semopm = SEMOPM;
 	ns->sc_semmni = SEMMNI;
 	ns->used_sems = 0;
-	ipc_init_ids(ids);
+	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
 }
 
 #ifdef CONFIG_IPC_NS
-int sem_init_ns(struct ipc_namespace *ns)
-{
-	struct ipc_ids *ids;
-
-	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
-	if (ids == NULL)
-		return -ENOMEM;
-
-	__sem_init_ns(ns, ids);
-	return 0;
-}
-
 void sem_exit_ns(struct ipc_namespace *ns)
 {
 	struct sem_array *sma;
@@ -163,15 +148,12 @@ void sem_exit_ns(struct ipc_namespace *ns)
 		total++;
 	}
 	up_write(&sem_ids(ns).rw_mutex);
-
-	kfree(ns->ids[IPC_SEM_IDS]);
-	ns->ids[IPC_SEM_IDS] = NULL;
 }
 #endif
 
 void __init sem_init (void)
 {
-	__sem_init_ns(&init_ipc_ns, &init_sem_ids);
+	sem_init_ns(&init_ipc_ns);
 	ipc_init_proc_interface("sysvipc/sem",
 				"       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n",
 				IPC_SEM_IDS, sysvipc_sem_proc_show);

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);

ipc/util.c

@@ -833,7 +833,7 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 	if (ipc && ipc != SEQ_START_TOKEN)
 		ipc_unlock(ipc);
 
-	return sysvipc_find_ipc(iter->ns->ids[iface->ids], *pos, pos);
+	return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 }
 
 /*
@@ -846,7 +846,7 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 	struct ipc_proc_iface *iface = iter->iface;
 	struct ipc_ids *ids;
 
-	ids = iter->ns->ids[iface->ids];
+	ids = &iter->ns->ids[iface->ids];
 
 	/*
 	 * Take the lock - this will be released by the corresponding
@@ -877,7 +877,7 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it)
 	if (ipc && ipc != SEQ_START_TOKEN)
 		ipc_unlock(ipc);
 
-	ids = iter->ns->ids[iface->ids];
+	ids = &iter->ns->ids[iface->ids];
 	/* Release the lock we took in start() */
 	up_read(&ids->rw_mutex);
 }

ipc/util.h

@@ -10,7 +10,6 @@
 #ifndef _IPC_UTIL_H
 #define _IPC_UTIL_H
 
-#include <linux/idr.h>
 #include <linux/err.h>
 
 #define USHRT_MAX 0xffff
@@ -22,22 +21,14 @@ void shm_init (void);
 
 struct ipc_namespace;
 
-int sem_init_ns(struct ipc_namespace *ns);
-int msg_init_ns(struct ipc_namespace *ns);
-int shm_init_ns(struct ipc_namespace *ns);
+void sem_init_ns(struct ipc_namespace *ns);
+void msg_init_ns(struct ipc_namespace *ns);
+void shm_init_ns(struct ipc_namespace *ns);
 
 void sem_exit_ns(struct ipc_namespace *ns);
 void msg_exit_ns(struct ipc_namespace *ns);
 void shm_exit_ns(struct ipc_namespace *ns);
 
-struct ipc_ids {
-	int in_use;
-	unsigned short seq;
-	unsigned short seq_max;
-	struct rw_semaphore rw_mutex;
-	struct idr ipcs_idr;
-};
-
 /*
  * Structure that holds the parameters needed by the ipc operations
  * (see after)
@@ -68,6 +59,7 @@ struct ipc_ops {
 };
 
 struct seq_file;
+struct ipc_ids;
 
 void ipc_init_ids(struct ipc_ids *);
 #ifdef CONFIG_PROC_FS