IPC: consolidate sem_exit_ns(), msg_exit_ns() and shm_exit_ns()

sem_exit_ns(), msg_exit_ns() and shm_exit_ns() are all called when an
ipc_namespace is released to free all ipcs of each type.  But in fact, they
do the same thing: they loop around all ipcs to free them individually by
calling a specific routine.

This patch proposes to consolidate this by introducing a common function,
free_ipcs(), that do the job.  The specific routine to call on each
individual ipcs is passed as parameter.  For this, these ipc-specific
'free' routines are reworked to take a generic 'struct ipc_perm' as
parameter.

Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Cc: 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

@@ -43,7 +43,10 @@ extern struct ipc_namespace init_ipc_ns;
 #if defined(CONFIG_SYSVIPC) && defined(CONFIG_IPC_NS)
 extern void free_ipc_ns(struct kref *kref);
 extern struct ipc_namespace *copy_ipcs(unsigned long flags,
-						struct ipc_namespace *ns);
+				       struct ipc_namespace *ns);
+extern void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
+		      void (*free)(struct ipc_namespace *,
+				   struct kern_ipc_perm *));
 
 static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 {

ipc/msg.c

@@ -72,7 +72,7 @@ struct msg_sender {
 #define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
 #define msg_buildid(id, seq)	ipc_buildid(id, seq)
 
-static void freeque(struct ipc_namespace *, struct msg_queue *);
+static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
 static int newque(struct ipc_namespace *, struct ipc_params *);
 #ifdef CONFIG_PROC_FS
 static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
@@ -91,26 +91,7 @@ void msg_init_ns(struct ipc_namespace *ns)
 #ifdef CONFIG_IPC_NS
 void msg_exit_ns(struct ipc_namespace *ns)
 {
-	struct msg_queue *msq;
+	free_ipcs(ns, &msg_ids(ns), freeque);
-	struct kern_ipc_perm *perm;
-	int next_id;
-	int total, in_use;
-
-	down_write(&msg_ids(ns).rw_mutex);
-
-	in_use = msg_ids(ns).in_use;
-
-	for (total = 0, next_id = 0; total < in_use; next_id++) {
-		perm = idr_find(&msg_ids(ns).ipcs_idr, next_id);
-		if (perm == NULL)
-			continue;
-		ipc_lock_by_ptr(perm);
-		msq = container_of(perm, struct msg_queue, q_perm);
-		freeque(ns, msq);
-		total++;
-	}
-
-	up_write(&msg_ids(ns).rw_mutex);
 }
 #endif
 
@@ -274,9 +255,10 @@ static void expunge_all(struct msg_queue *msq, int res)
  * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
  * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
  */
-static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
+static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 {
 	struct list_head *tmp;
+	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 
 	expunge_all(msq, -EIDRM);
 	ss_wakeup(&msq->q_senders, 1);
@@ -582,7 +564,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
 		break;
 	}
 	case IPC_RMID:
-		freeque(ns, msq);
+		freeque(ns, &msq->q_perm);
 		break;
 	}
 	err = 0;

ipc/namespace.c

@@ -44,6 +44,36 @@ struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
 	return new_ns;
 }
 
+/*
+ * free_ipcs - free all ipcs of one type
+ * @ns:   the namespace to remove the ipcs from
+ * @ids:  the table of ipcs to free
+ * @free: the function called to free each individual ipc
+ *
+ * Called for each kind of ipc when an ipc_namespace exits.
+ */
+void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
+	       void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
+{
+	struct kern_ipc_perm *perm;
+	int next_id;
+	int total, in_use;
+
+	down_write(&ids->rw_mutex);
+
+	in_use = ids->in_use;
+
+	for (total = 0, next_id = 0; total < in_use; next_id++) {
+		perm = idr_find(&ids->ipcs_idr, next_id);
+		if (perm == NULL)
+			continue;
+		ipc_lock_by_ptr(perm);
+		free(ns, perm);
+		total++;
+	}
+	up_write(&ids->rw_mutex);
+}
+
 void free_ipc_ns(struct kref *kref)
 {
 	struct ipc_namespace *ns;

ipc/sem.c

@@ -94,7 +94,7 @@
 #define sem_buildid(id, seq)	ipc_buildid(id, seq)
 
 static int newary(struct ipc_namespace *, struct ipc_params *);
-static void freeary(struct ipc_namespace *, struct sem_array *);
+static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
 #ifdef CONFIG_PROC_FS
 static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
 #endif
@@ -129,25 +129,7 @@ void sem_init_ns(struct ipc_namespace *ns)
 #ifdef CONFIG_IPC_NS
 void sem_exit_ns(struct ipc_namespace *ns)
 {
-	struct sem_array *sma;
+	free_ipcs(ns, &sem_ids(ns), freeary);
-	struct kern_ipc_perm *perm;
-	int next_id;
-	int total, in_use;
-
-	down_write(&sem_ids(ns).rw_mutex);
-
-	in_use = sem_ids(ns).in_use;
-
-	for (total = 0, next_id = 0; total < in_use; next_id++) {
-		perm = idr_find(&sem_ids(ns).ipcs_idr, next_id);
-		if (perm == NULL)
-			continue;
-		ipc_lock_by_ptr(perm);
-		sma = container_of(perm, struct sem_array, sem_perm);
-		freeary(ns, sma);
-		total++;
-	}
-	up_write(&sem_ids(ns).rw_mutex);
 }
 #endif
 
@@ -542,10 +524,11 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
  * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
  * remains locked on exit.
  */
-static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
+static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 {
 	struct sem_undo *un;
 	struct sem_queue *q;
+	struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm);
 
 	/* Invalidate the existing undo structures for this semaphore set.
 	 * (They will be freed without any further action in exit_sem()
@@ -926,7 +909,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
 
 	switch(cmd){
 	case IPC_RMID:
-		freeary(ns, sma);
+		freeary(ns, ipcp);
 		err = 0;
 		break;
 	case IPC_SET:

ipc/shm.c

@@ -83,8 +83,11 @@ void shm_init_ns(struct ipc_namespace *ns)
  * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
  * Only shm_ids.rw_mutex remains locked on exit.
  */
-static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
+static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 {
+	struct shmid_kernel *shp;
+	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
+
 	if (shp->shm_nattch){
 		shp->shm_perm.mode |= SHM_DEST;
 		/* Do not find it any more */
@@ -97,25 +100,7 @@ static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
 #ifdef CONFIG_IPC_NS
 void shm_exit_ns(struct ipc_namespace *ns)
 {
-	struct shmid_kernel *shp;
+	free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
-	struct kern_ipc_perm *perm;
-	int next_id;
-	int total, in_use;
-
-	down_write(&shm_ids(ns).rw_mutex);
-
-	in_use = shm_ids(ns).in_use;
-
-	for (total = 0, next_id = 0; total < in_use; next_id++) {
-		perm = idr_find(&shm_ids(ns).ipcs_idr, next_id);
-		if (perm == NULL)
-			continue;
-		ipc_lock_by_ptr(perm);
-		shp = container_of(perm, struct shmid_kernel, shm_perm);
-		do_shm_rmid(ns, shp);
-		total++;
-	}
-	up_write(&shm_ids(ns).rw_mutex);
 }
 #endif
 
@@ -832,7 +817,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 		if (err)
 			goto out_unlock_up;
 
-		do_shm_rmid(ns, shp);
+		do_shm_rmid(ns, &shp->shm_perm);
 		up_write(&shm_ids(ns).rw_mutex);
 		goto out;
 	}