2.6.25-rc7

 kernel

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
new file mode 100644
index 0000000..6d792b6
--- /dev/null
+++ b/kernel/pid_namespace.c
@@ -0,0 +1,197 @@
+/*
+ * Pid namespaces
+ *
+ * Authors:
+ *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
+ *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
+ *     Many thanks to Oleg Nesterov for comments and help
+ *
+ */
+
+#include <linux/pid.h>
+#include <linux/pid_namespace.h>
+#include <linux/syscalls.h>
+#include <linux/err.h>
+
+#define BITS_PER_PAGE      (PAGE_SIZE*8)
+
+struct pid_cache {
+   int nr_ids;
+   char name[16];
+   struct kmem_cache *cachep;
+   struct list_head list;
+};
+
+static LIST_HEAD(pid_caches_lh);
+static DEFINE_MUTEX(pid_caches_mutex);
+static struct kmem_cache *pid_ns_cachep;
+
+/*
+ * creates the kmem cache to allocate pids from.
+ * @nr_ids: the number of numerical ids this pid will have to carry
+ */
+
+static struct kmem_cache *create_pid_cachep(int nr_ids)
+{
+   struct pid_cache *pcache;
+   struct kmem_cache *cachep;
+
+   mutex_lock(&pid_caches_mutex);
+   list_for_each_entry(pcache, &pid_caches_lh, list)
+      if (pcache->nr_ids == nr_ids)
+         goto out;
+
+   pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
+   if (pcache == NULL)
+      goto err_alloc;
+
+   snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
+   cachep = kmem_cache_create(pcache->name,
+         sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
+         0, SLAB_HWCACHE_ALIGN, NULL);
+   if (cachep == NULL)
+      goto err_cachep;
+
+   pcache->nr_ids = nr_ids;
+   pcache->cachep = cachep;
+   list_add(&pcache->list, &pid_caches_lh);
+out:
+   mutex_unlock(&pid_caches_mutex);
+   return pcache->cachep;
+
+err_cachep:
+   kfree(pcache);
+err_alloc:
+   mutex_unlock(&pid_caches_mutex);
+   return NULL;
+}
+
+static struct pid_namespace *create_pid_namespace(int level)
+{
+   struct pid_namespace *ns;
+   int i;
+
+   ns = kmem_cache_alloc(pid_ns_cachep, GFP_KERNEL);
+   if (ns == NULL)
+      goto out;
+
+   ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
+   if (!ns->pidmap[0].page)
+      goto out_free;
+
+   ns->pid_cachep = create_pid_cachep(level + 1);
+   if (ns->pid_cachep == NULL)
+      goto out_free_map;
+
+   kref_init(&ns->kref);
+   ns->last_pid = 0;
+   ns->child_reaper = NULL;
+   ns->level = level;
+
+   set_bit(0, ns->pidmap[0].page);
+   atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
+
+   for (i = 1; i < PIDMAP_ENTRIES; i++) {
+      ns->pidmap[i].page = 0;
+      atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
+   }
+
+   return ns;
+
+out_free_map:
+   kfree(ns->pidmap[0].page);
+out_free:
+   kmem_cache_free(pid_ns_cachep, ns);
+out:
+   return ERR_PTR(-ENOMEM);
+}
+
+static void destroy_pid_namespace(struct pid_namespace *ns)
+{
+   int i;
+
+   for (i = 0; i < PIDMAP_ENTRIES; i++)
+      kfree(ns->pidmap[i].page);
+   kmem_cache_free(pid_ns_cachep, ns);
+}
+
+struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
+{
+   struct pid_namespace *new_ns;
+
+   BUG_ON(!old_ns);
+   new_ns = get_pid_ns(old_ns);
+   if (!(flags & CLONE_NEWPID))
+      goto out;
+
+   new_ns = ERR_PTR(-EINVAL);
+   if (flags & CLONE_THREAD)
+      goto out_put;
+
+   new_ns = create_pid_namespace(old_ns->level + 1);
+   if (!IS_ERR(new_ns))
+      new_ns->parent = get_pid_ns(old_ns);
+
+out_put:
+   put_pid_ns(old_ns);
+out:
+   return new_ns;
+}
+
+void free_pid_ns(struct kref *kref)
+{
+   struct pid_namespace *ns, *parent;
+
+   ns = container_of(kref, struct pid_namespace, kref);
+
+   parent = ns->parent;
+   destroy_pid_namespace(ns);
+
+   if (parent != NULL)
+      put_pid_ns(parent);
+}
+
+void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+{
+   int nr;
+   int rc;
+
+   /*
+    * The last thread in the cgroup-init thread group is terminating.
+    * Find remaining pid_ts in the namespace, signal and wait for them
+    * to exit.
+    *
+    * Note:  This signals each threads in the namespace - even those that
+    *      belong to the same thread group, To avoid this, we would have
+    *      to walk the entire tasklist looking a processes in this
+    *      namespace, but that could be unnecessarily expensive if the
+    *      pid namespace has just a few processes. Or we need to
+    *      maintain a tasklist for each pid namespace.
+    *
+    */
+   read_lock(&tasklist_lock);
+   nr = next_pidmap(pid_ns, 1);
+   while (nr > 0) {
+      kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);
+      nr = next_pidmap(pid_ns, nr);
+   }
+   read_unlock(&tasklist_lock);
+
+   do {
+      clear_thread_flag(TIF_SIGPENDING);
+      rc = sys_wait4(-1, NULL, __WALL, NULL);
+   } while (rc != -ECHILD);
+
+
+   /* Child reaper for the pid namespace is going away */
+   pid_ns->child_reaper = NULL;
+   return;
+}
+
+static __init int pid_namespaces_init(void)
+{
+   pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
+   return 0;
+}
+
+__initcall(pid_namespaces_init);