2.6.24-rc3

 kernel

diff --git a/kernel/pid.c b/kernel/pid.c
index c6e3f9f..f815455 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -18,6 +18,12 @@
  * allocation scenario when all but one out of 1 million PIDs possible are
  * allocated already: the scanning of 32 list entries and at most PAGE_SIZE
  * bytes. The typical fastpath is a single successful setbit. Freeing is O(1).
+ *
+ * Pid namespaces:
+ *    (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/mm.h>
@@ -28,12 +34,14 @@
 #include <linux/hash.h>
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
+#include <linux/syscalls.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;
-static struct kmem_cache *pid_cachep;
 struct pid init_struct_pid = INIT_STRUCT_PID;
+static struct kmem_cache *pid_ns_cachep;
 
 int pid_max = PID_MAX_DEFAULT;
 
@@ -68,8 +76,25 @@ struct pid_namespace init_pid_ns = {
       [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
    },
    .last_pid = 0,
-   .child_reaper = &init_task
+   .level = 0,
+   .child_reaper = &init_task,
 };
+EXPORT_SYMBOL_GPL(init_pid_ns);
+
+int is_container_init(struct task_struct *tsk)
+{
+   int ret = 0;
+   struct pid *pid;
+
+   rcu_read_lock();
+   pid = task_pid(tsk);
+   if (pid != NULL && pid->numbers[pid->level].nr == 1)
+      ret = 1;
+   rcu_read_unlock();
+
+   return ret;
+}
+EXPORT_SYMBOL(is_container_init);
 
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
@@ -176,11 +201,17 @@ static int next_pidmap(struct pid_namespace *pid_ns, int last)
 
 fastcall void put_pid(struct pid *pid)
 {
+   struct pid_namespace *ns;
+
    if (!pid)
       return;
+
+   ns = pid->numbers[pid->level].ns;
    if ((atomic_read(&pid->count) == 1) ||
-        atomic_dec_and_test(&pid->count))
-      kmem_cache_free(pid_cachep, pid);
+        atomic_dec_and_test(&pid->count)) {
+      kmem_cache_free(ns->pid_cachep, pid);
+      put_pid_ns(ns);
+   }
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -193,60 +224,94 @@ static void delayed_put_pid(struct rcu_head *rhp)
 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;
+   int i, nr;
+   struct pid_namespace *tmp;
+   struct upid *upid;
 
-   pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
+   pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
    if (!pid)
       goto out;
 
-   nr = alloc_pidmap(current->nsproxy->pid_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;
+   }
 
+   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 = ns->level; i >= 0; i--) {
+      upid = &pid->numbers[i];
+      hlist_add_head_rcu(&upid->pid_chain,
+            &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
+   }
    spin_unlock_irq(&pidmap_lock);
 
 out:
    return pid;
 
 out_free:
-   kmem_cache_free(pid_cachep, pid);
+   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;
 }
 
-struct pid * fastcall find_pid(int nr)
+struct pid * fastcall find_pid_ns(int nr, struct pid_namespace *ns)
 {
    struct hlist_node *elem;
-   struct pid *pid;
+   struct upid *pnr;
+
+   hlist_for_each_entry_rcu(pnr, elem,
+         &pid_hash[pid_hashfn(nr, ns)], pid_chain)
+      if (pnr->nr == nr && pnr->ns == ns)
+         return container_of(pnr, struct pid,
+               numbers[ns->level]);
 
-   hlist_for_each_entry_rcu(pid, elem,
-         &pid_hash[pid_hashfn(nr)], pid_chain) {
-      if (pid->nr == nr)
-         return pid;
-   }
    return NULL;
 }
+EXPORT_SYMBOL_GPL(find_pid_ns);
+
+struct pid *find_vpid(int nr)
+{
+   return find_pid_ns(nr, current->nsproxy->pid_ns);
+}
+EXPORT_SYMBOL_GPL(find_vpid);
+
+struct pid *find_pid(int nr)
+{
+   return find_pid_ns(nr, &init_pid_ns);
+}
 EXPORT_SYMBOL_GPL(find_pid);
 
 /*
@@ -307,12 +372,32 @@ struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type)
 /*
  * Must be called under rcu_read_lock() or with tasklist_lock read-held.
  */
-struct task_struct *find_task_by_pid_type(int type, int nr)
+struct task_struct *find_task_by_pid_type_ns(int type, int nr,
+      struct pid_namespace *ns)
 {
-   return pid_task(find_pid(nr), type);
+   return pid_task(find_pid_ns(nr, ns), type);
 }
 
-EXPORT_SYMBOL(find_task_by_pid_type);
+EXPORT_SYMBOL(find_task_by_pid_type_ns);
+
+struct task_struct *find_task_by_pid(pid_t nr)
+{
+   return find_task_by_pid_type_ns(PIDTYPE_PID, nr, &init_pid_ns);
+}
+EXPORT_SYMBOL(find_task_by_pid);
+
+struct task_struct *find_task_by_vpid(pid_t vnr)
+{
+   return find_task_by_pid_type_ns(PIDTYPE_PID, vnr,
+         current->nsproxy->pid_ns);
+}
+EXPORT_SYMBOL(find_task_by_vpid);
+
+struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns)
+{
+   return find_task_by_pid_type_ns(PIDTYPE_PID, nr, ns);
+}
+EXPORT_SYMBOL(find_task_by_pid_ns);
 
 struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
 {
@@ -339,45 +424,241 @@ struct pid *find_get_pid(pid_t nr)
    struct pid *pid;
 
    rcu_read_lock();
-   pid = get_pid(find_pid(nr));
+   pid = get_pid(find_vpid(nr));
    rcu_read_unlock();
 
    return pid;
 }
 
+pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns)
+{
+   struct upid *upid;
+   pid_t nr = 0;
+
+   if (pid && ns->level <= pid->level) {
+      upid = &pid->numbers[ns->level];
+      if (upid->ns == ns)
+         nr = upid->nr;
+   }
+   return nr;
+}
+
+pid_t task_pid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+   return pid_nr_ns(task_pid(tsk), ns);
+}
+EXPORT_SYMBOL(task_pid_nr_ns);
+
+pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+   return pid_nr_ns(task_tgid(tsk), ns);
+}
+EXPORT_SYMBOL(task_tgid_nr_ns);
+
+pid_t task_pgrp_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+   return pid_nr_ns(task_pgrp(tsk), ns);
+}
+EXPORT_SYMBOL(task_pgrp_nr_ns);
+
+pid_t task_session_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+   return pid_nr_ns(task_session(tsk), ns);
+}
+EXPORT_SYMBOL(task_session_nr_ns);
+
 /*
  * Used by proc to find the first pid that is greater then or equal to nr.
  *
  * If there is a pid at nr this function is exactly the same as find_pid.
  */
-struct pid *find_ge_pid(int nr)
+struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
 {
    struct pid *pid;
 
    do {
-      pid = find_pid(nr);
+      pid = find_pid_ns(nr, ns);
       if (pid)
          break;
-      nr = next_pidmap(current->nsproxy->pid_ns, nr);
+      nr = next_pidmap(ns, nr);
    } while (nr > 0);
 
    return pid;
 }
 EXPORT_SYMBOL_GPL(find_get_pid);
 
+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);
+
+/*
+ * 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;
+}
+
+#ifdef CONFIG_PID_NS
+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);
-   get_pid_ns(old_ns);
-   return 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;
+   struct pid_namespace *ns, *parent;
 
    ns = container_of(kref, struct pid_namespace, kref);
-   kfree(ns);
+
+   parent = ns->parent;
+   destroy_pid_namespace(ns);
+
+   if (parent != NULL)
+      put_pid_ns(parent);
+}
+#endif /* CONFIG_PID_NS */
+
+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;
 }
 
 /*
@@ -412,5 +693,9 @@ void __init pidmap_init(void)
    set_bit(0, init_pid_ns.pidmap[0].page);
    atomic_dec(&init_pid_ns.pidmap[0].nr_free);
 
-   pid_cachep = KMEM_CACHE(pid, SLAB_PANIC);
+   init_pid_ns.pid_cachep = create_pid_cachep(1);
+   if (init_pid_ns.pid_cachep == NULL)
+      panic("Can't create pid_1 cachep\n");
+
+   pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
 }