4 files changed, 113 insertions, 22 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b0bf326143a..1301c087537 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -25,6 +25,7 @@
 #define CLONE_NEWUTS            0x04000000      /* New utsname group? */
 #define CLONE_NEWIPC            0x08000000      /* New ipcs */
 #define CLONE_NEWUSER           0x10000000      /* New user namespace */
+#define CLONE_NEWPID            0x20000000      /* New pid namespace */
 #define CLONE_NEWNET            0x40000000      /* New network namespace */
 
 /*
diff --git a/kernel/fork.c b/kernel/fork.c
index bab34192799..f252784f933 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -973,7 +973,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                                         unsigned long stack_start,
                                         struct pt_regs *regs,
                                         unsigned long stack_size,
-                                        int __user *parent_tidptr,
                                         int __user *child_tidptr,
                                         struct pid *pid)
 {
@@ -1043,11 +1042,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->did_exec = 0;
         delayacct_tsk_init(p);  /* Must remain after dup_task_struct() */
         copy_flags(clone_flags, p);
-        retval = -EFAULT;
-        if (clone_flags & CLONE_PARENT_SETTID)
-                if (put_user(p->pid, parent_tidptr))
-                        goto bad_fork_cleanup_delays_binfmt;
-
         INIT_LIST_HEAD(&p->children);
         INIT_LIST_HEAD(&p->sibling);
         p->vfork_done = NULL;
@@ -1289,11 +1283,22 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                         __ptrace_link(p, current->parent);
 
                 if (thread_group_leader(p)) {
-                        p->signal->tty = current->signal->tty;
-                        p->signal->pgrp = task_pgrp_nr(current);
-                        set_task_session(p, task_session_nr(current));
-                        attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
-                        attach_pid(p, PIDTYPE_SID, task_session(current));
+                        if (clone_flags & CLONE_NEWPID) {
+                                p->nsproxy->pid_ns->child_reaper = p;
+                                p->signal->tty = NULL;
+                                p->signal->pgrp = p->pid;
+                                set_task_session(p, p->pid);
+                                attach_pid(p, PIDTYPE_PGID, pid);
+                                attach_pid(p, PIDTYPE_SID, pid);
+                        } else {
+                                p->signal->tty = current->signal->tty;
+                                p->signal->pgrp = task_pgrp_nr(current);
+                                set_task_session(p, task_session_nr(current));
+                                attach_pid(p, PIDTYPE_PGID,
+                                                task_pgrp(current));
+                                attach_pid(p, PIDTYPE_SID,
+                                                task_session(current));
+                        }
 
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
                         __get_cpu_var(process_counts)++;
@@ -1339,7 +1344,6 @@ bad_fork_cleanup_policy:
 bad_fork_cleanup_cgroup:
 #endif
         cgroup_exit(p, cgroup_callbacks_done);
-bad_fork_cleanup_delays_binfmt:
         delayacct_tsk_free(p);
         if (p->binfmt)
                 module_put(p->binfmt->module);
@@ -1366,7 +1370,7 @@ struct task_struct * __cpuinit fork_idle(int cpu)
         struct task_struct *task;
         struct pt_regs regs;
 
-        task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL,
+        task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
                                 &init_struct_pid);
         if (!IS_ERR(task))
                 init_idle(task, cpu);
@@ -1414,7 +1418,7 @@ long do_fork(unsigned long clone_flags,
         }
 
         p = copy_process(clone_flags, stack_start, regs, stack_size,
-                        parent_tidptr, child_tidptr, NULL);
+                        child_tidptr, NULL);
         /*
          * Do this prior waking up the new thread - the thread pointer
          * might get invalid after that point, if the thread exits quickly.
@@ -1422,7 +1426,16 @@ long do_fork(unsigned long clone_flags,
         if (!IS_ERR(p)) {
                 struct completion vfork;
 
-                nr = pid_nr(task_pid(p));
+                /*
+                 * this is enough to call pid_nr_ns here, but this if
+                 * improves optimisation of regular fork()
+                 */
+                nr = (clone_flags & CLONE_NEWPID) ?
+                        task_pid_nr_ns(p, current->nsproxy->pid_ns) :
+                                task_pid_vnr(p);
+
+                if (clone_flags & CLONE_PARENT_SETTID)
+                        put_user(nr, parent_tidptr);
 
                 if (clone_flags & CLONE_VFORK) {
                         p->vfork_done = &vfork;
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index c8ef7c2992e..79f871bc0ef 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -129,7 +129,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
 
         get_nsproxy(old_ns);
 
-        if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER | CLONE_NEWNET)))
+        if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
+                                CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNET)))
                 return 0;
 
         if (!capable(CAP_SYS_ADMIN)) {
diff --git a/kernel/pid.c b/kernel/pid.c
index 4b17acdb862..f76097c6047 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>
@@ -456,8 +462,8 @@ static struct kmem_cache *create_pid_cachep(int nr_ids)
 
         snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
         cachep = kmem_cache_create(pcache->name,
-                        /* FIXME add numerical ids here */
-                        sizeof(struct pid), 0, SLAB_HWCACHE_ALIGN, NULL);
+                        sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
+                        0, SLAB_HWCACHE_ALIGN, NULL);
         if (cachep == NULL)
                 goto err_cachep;
 
@@ -475,19 +481,89 @@ err_alloc:
         return NULL;
 }
 
+static struct pid_namespace *create_pid_namespace(int level)
+{
+        struct pid_namespace *ns;
+        int i;
+
+        ns = kmalloc(sizeof(struct pid_namespace), 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:
+        kfree(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);
+        kfree(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);
 }
 
 /*