[Devel] [PATCH 8/20] Make alloc_pid(), free_pid() and put_pid() work with struct upid

[xemul at openvz.org]

Each struct upid element of struct pid has to be initialized properly,
i.e. its nr mst be allocated from appropriate pidmap and ns set to
appropriate namespace.

When allocating a new pid, we need to know the namespace this pid will
live in, so the additional argument is added to alloc_pid().

On the other hand, the rest of the kernel still uses the pid->nr and
pid->pid_chain fields, so these ones are still initialized, but this
will be removed soon.

Signed-off-by: Pavel Emelyanov <xemul at openvz.org>

---

 include/linux/pid.h |    2 +-
 kernel/fork.c       |    2 +-
 kernel/pid.c        |   49 ++++++++++++++++++++++++++++++++++---------------
 3 files changed, 36 insertions(+), 17 deletions(-)

--- ./include/linux/pid.h.ve8	2007-08-06 15:39:05.000000000 +0400
+++ ./include/linux/pid.h	2007-08-06 15:39:05.000000000 +0400
@@ -111,7 +111,7 @@ extern struct pid *FASTCALL(find_pid(int
 extern struct pid *find_get_pid(int nr);
 extern struct pid *find_ge_pid(int nr);
 
-extern struct pid *alloc_pid(void);
+extern struct pid *alloc_pid(struct pid_namespace *ns);
 extern void FASTCALL(free_pid(struct pid *pid));
 
 static inline pid_t pid_nr(struct pid *pid)
--- ./kernel/fork.c.ve8	2007-08-06 15:39:02.000000000 +0400
+++ ./kernel/fork.c	2007-08-06 15:39:05.000000000 +0400
@@ -1029,7 +1029,7 @@ static struct task_struct *copy_process(
 		goto bad_fork_cleanup_put_domain;
 
 	if (pid != &init_struct_pid) {
-		pid = alloc_pid();
+		pid = alloc_pid(task_active_pid_ns(p));
 		if (!pid)
 			goto bad_fork_put_binfmt_module;
 	}
--- ./kernel/pid.c.ve8	2007-08-06 15:39:05.000000000 +0400
+++ ./kernel/pid.c	2007-08-06 15:41:34.000000000 +0400
@@ -29,7 +29,8 @@
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
 
-#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
+#define pid_hashfn(nr, ns)	\
+	hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
 struct pid init_struct_pid = INIT_STRUCT_PID;
@@ -188,11 +189,13 @@ fastcall void put_pid(struct pid *pid)
 	if (!pid)
 		return;
 
-	/* FIXME - this must be the namespace this pid lives in */
-	ns = &init_pid_ns;
+	ns = pid->numbers[pid->level].ns;
 	if ((atomic_read(&pid->count) == 1) ||
-	     atomic_dec_and_test(&pid->count))
+	     atomic_dec_and_test(&pid->count)) {
 		kmem_cache_free(ns->pid_cachep, pid);
+		if (ns != &init_pid_ns)
+			put_pid_ns(ns);
+	}
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -205,45 +208,61 @@ 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 */
+	int i;
 	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);
+	for (i = 0; i <= pid->level; i++)
+		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
 	call_rcu(&pid->rcu, delayed_put_pid);
 }
 
-struct pid *alloc_pid(void)
+struct pid *alloc_pid(struct pid_namespace *ns)
 {
 	struct pid *pid;
 	enum pid_type type;
-	int nr = -1;
-	struct pid_namespace *ns;
+	int i, nr;
+	struct pid_namespace *tmp;
 
-	ns = task_active_pid_ns(current);
 	pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
 	if (!pid)
 		goto out;
 
-	nr = alloc_pidmap(ns);
-	if (nr < 0)
-		goto out_free;
+	tmp = ns;
+	for (i = ns->level; i >= 0; i--) {
+		nr = alloc_pidmap(tmp);
+		if (nr < 0)
+			goto out_free;
+
+		pid->numbers[i].nr = nr;
+		pid->numbers[i].ns = tmp;
+		tmp = tmp->parent;
+	}
+
+	if (ns != &init_pid_ns)
+		get_pid_ns(ns);
 
+	pid->level = ns->level;
+	pid->nr = pid->numbers[0].nr;
 	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)]);
+	hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr, ns)]);
 	spin_unlock_irq(&pidmap_lock);
 
 out:
 	return pid;
 
 out_free:
+	for (i++; i <= ns->level; i++)
+		free_pidmap(pid->numbers[i].ns, pid->numbers[i].nr);
+
 	kmem_cache_free(ns->pid_cachep, pid);
 	pid = NULL;
 	goto out;
@@ -255,7 +274,7 @@ struct pid * fastcall find_pid(int nr)
 	struct pid *pid;
 
 	hlist_for_each_entry_rcu(pid, elem,
-			&pid_hash[pid_hashfn(nr)], pid_chain) {
+			&pid_hash[pid_hashfn(nr, &init_pid_ns)], pid_chain) {
 		if (pid->nr == nr)
 			return pid;
 	}