The alloc_pid(), free_pid() and put_pid() are splitted into two parts
 - the generic pid manipulation, like refcount and task hlist heads;
 - manipulations with pids numerical values.

E.g. alloc pid allocates the struct pid and initializes its refcount etc and
calls the alloc_pid_nrs() to allocate the pid numerical ids and hash it into
the hash-tables.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

 pid.c |   90 +++++++++++++++++++++++++++++++++++++++++-------------------------
 1 files changed, 56 insertions(+), 34 deletions(-)

--- ./kernel/pid.c.pidsplit	2007-06-14 15:57:41.000000000 +0400
+++ ./kernel/pid.c	2007-06-14 16:34:28.000000000 +0400
@@ -174,13 +174,64 @@ static int next_pidmap(struct pid_namesp
 	return -1;
 }
 
+#ifndef CONFIG_PID_NS
+static inline int alloc_pid_nrs(struct pid *pid)
+{
+	int nr;
+
+	nr = alloc_pidmap(&init_pid_ns);
+	if (nr < 0)
+		return nr;
+
+	pid->nr = nr;
+	spin_lock_irq(&pidmap_lock);
+	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(nr)]);
+	spin_unlock_irq(&pidmap_lock);
+	return 0;
+}
+
+static inline void unhash_pid_nrs(struct pid *pid)
+{
+	/* We can be called with write_lock_irq(&tasklist_lock) held */
+	unsigned long flags;
+
+	spin_lock_irqsave(&pidmap_lock, flags);
+	hlist_del_rcu(&pid->pid_chain);
+	spin_unlock_irqrestore(&pidmap_lock, flags);
+
+	free_pidmap(&init_pid_ns, pid->nr);
+}
+
+static inline void free_pid_nrs(struct pid *pid)
+{
+}
+
+struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
+{
+	struct hlist_node *elem;
+	struct pid *pid;
+
+	hlist_for_each_entry_rcu(pid, elem,
+			&pid_hash[pid_hashfn(nr)], pid_chain) {
+		if (pid->nr == nr)
+			return pid;
+	}
+	return NULL;
+}
+#else
+#endif
+
+EXPORT_SYMBOL_GPL(find_pid_ns);
+
 fastcall void put_pid(struct pid *pid)
 {
 	if (!pid)
 		return;
 	if ((atomic_read(&pid->count) == 1) ||
-	     atomic_dec_and_test(&pid->count))
+	     atomic_dec_and_test(&pid->count)) {
+		free_pid_nrs(pid);
 		kmem_cache_free(pid_cachep, pid);
+	}
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -192,14 +243,7 @@ static void delayed_put_pid(struct rcu_h
 
 fastcall void free_pid(struct pid *pid)
 {
-	/* We can be called with write_lock_irq(&tasklist_lock) held */
-	unsigned long flags;
-
-	spin_lock_irqsave(&pidmap_lock, flags);
-	hlist_del_rcu(&pid->pid_chain);
-	spin_unlock_irqrestore(&pidmap_lock, flags);
-
-	free_pidmap(&init_pid_ns, pid->nr);
+	unhash_pid_nrs(pid);
 	call_rcu(&pid->rcu, delayed_put_pid);
 }
 
@@ -207,47 +251,25 @@ struct pid *alloc_pid(void)
 {
 	struct pid *pid;
 	enum pid_type type;
-	int nr = -1;
 
 	pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
 	if (!pid)
 		goto out;
 
-	nr = alloc_pidmap(current->nsproxy->pid_ns);
-	if (nr < 0)
-		goto out_free;
-
 	atomic_set(&pid->count, 1);
-	pid->nr = nr;
 	for (type = 0; type < PIDTYPE_MAX; ++type)
 		INIT_HLIST_HEAD(&pid->tasks[type]);
 
-	spin_lock_irq(&pidmap_lock);
-	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);
-	spin_unlock_irq(&pidmap_lock);
+	if (alloc_pid_nrs(pid))
+		goto out_free;
 
-out:
 	return pid;
 
 out_free:
 	kmem_cache_free(pid_cachep, pid);
-	pid = NULL;
-	goto out;
-}
-
-struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
-{
-	struct hlist_node *elem;
-	struct pid *pid;
-
-	hlist_for_each_entry_rcu(pid, elem,
-			&pid_hash[pid_hashfn(nr)], pid_chain) {
-		if (pid->nr == nr)
-			return pid;
-	}
+out:
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(find_pid_ns);
 
 /*
  * attach_pid() must be called with the tasklist_lock write-held.
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