[PATCH 6/15] Make alloc_pid(), free_pid() and put_pid() work with struct upid

[Pavel Emelyanov <xemul@xxxxxxxxxx>]

Each struct upid element of struct pid has to be initialized properly,
i.e. its nr mst be allocated from appropriate pidmap and it must be
inserted into the hash.

Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>

---

include/linux/pid.h |    2 +-
kernel/pid.c        |   52 +++++++++++++++++++++++++++++++++++++---------------
2 files changed, 38 insertions(+), 16 deletions(-)

diff -upr linux-2.6.23-rc1-mm1.orig/include/linux/pid.h linux-2.6.23-rc1-mm1-7/include/linux/pid.h
--- linux-2.6.23-rc1-mm1.orig/include/linux/pid.h	2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/include/linux/pid.h	2007-07-26 16:36:37.000000000 +0400
@@ -83,7 +92,7 @@ extern void FASTCALL(detach_pid(struct t
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)
diff -upr linux-2.6.23-rc1-mm1.orig/kernel/pid.c linux-2.6.23-rc1-mm1-7/kernel/pid.c
--- linux-2.6.23-rc1-mm1.orig/kernel/pid.c	2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/kernel/pid.c	2007-07-26 16:36:37.000000000 +0400
@@ -28,7 +28,8 @@
#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;
@@ -187,11 +202,13 @@ 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);

@@ -204,45 +221,64 @@ 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);
+	for (i = 0; i <= pid->level; i++)
+		hlist_del_rcu(&pid->numbers[i].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;
	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)]);
+	for (i = pid->level; i >= 0; i--)
+		hlist_add_head_rcu(&pid->numbers[i].pid_chain,
+				&pid_hash[pid_hashfn(pid->numbers[i].nr,
+					pid->numbers[i].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;

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