namespaces: cleanup the code managed with PID_NS option

Just like with the user namespaces, move the namespace management code into
the separate .c file and mark the (already existing) PID_NS option as "depend
on NAMESPACES"

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 197 insertions, 0 deletions

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
new file mode 100644
index 00000000000..6d792b66d85
--- /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);