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authorDaniel Lezcano <daniel.lezcano@free.fr>2011-05-27 03:25:23 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-27 04:12:34 +0400
commita77aea92010acf54ad785047234418d5d68772e2 (patch)
treec7cb57b62fd02bee2baceb79251923f7caec6139 /kernel
parentd846687d7f84e45f23ecf3846dbb43312a1206dd (diff)
downloadlinux-a77aea92010acf54ad785047234418d5d68772e2.tar.xz
cgroup: remove the ns_cgroup
The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and leads to some problems: * cgroup creation is out-of-control * cgroup name can conflict when pids are looping * it is not possible to have a single process handling a lot of namespaces without falling in a exponential creation time * we may want to create a namespace without creating a cgroup The ns_cgroup was replaced by a compatibility flag 'clone_children', where a newly created cgroup will copy the parent cgroup values. The userspace has to manually create a cgroup and add a task to the 'tasks' file. This patch removes the ns_cgroup as suggested in the following thread: https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html The 'cgroup_clone' function is removed because it is no longer used. This is a userspace-visible change. Commit 45531757b45c ("cgroup: notify ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a printk warning users that the feature is planned for removal. Since that time we have heard from XXX users who were affected by this. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Acked-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/cgroup.c116
-rw-r--r--kernel/cpuset.c7
-rw-r--r--kernel/fork.c6
-rw-r--r--kernel/ns_cgroup.c118
-rw-r--r--kernel/nsproxy.c4
6 files changed, 3 insertions, 249 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index e9cf19155b46..2d64cfcc8b42 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -61,7 +61,6 @@ obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_CGROUPS) += cgroup.o
obj-$(CONFIG_CGROUP_FREEZER) += cgroup_freezer.o
obj-$(CONFIG_CPUSETS) += cpuset.o
-obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o
obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 00a884342d3d..2731d115d725 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4630,122 +4630,6 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
}
/**
- * cgroup_clone - clone the cgroup the given subsystem is attached to
- * @tsk: the task to be moved
- * @subsys: the given subsystem
- * @nodename: the name for the new cgroup
- *
- * Duplicate the current cgroup in the hierarchy that the given
- * subsystem is attached to, and move this task into the new
- * child.
- */
-int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *subsys,
- char *nodename)
-{
- struct dentry *dentry;
- int ret = 0;
- struct cgroup *parent, *child;
- struct inode *inode;
- struct css_set *cg;
- struct cgroupfs_root *root;
- struct cgroup_subsys *ss;
-
- /* We shouldn't be called by an unregistered subsystem */
- BUG_ON(!subsys->active);
-
- /* First figure out what hierarchy and cgroup we're dealing
- * with, and pin them so we can drop cgroup_mutex */
- mutex_lock(&cgroup_mutex);
- again:
- root = subsys->root;
- if (root == &rootnode) {
- mutex_unlock(&cgroup_mutex);
- return 0;
- }
-
- /* Pin the hierarchy */
- if (!atomic_inc_not_zero(&root->sb->s_active)) {
- /* We race with the final deactivate_super() */
- mutex_unlock(&cgroup_mutex);
- return 0;
- }
-
- /* Keep the cgroup alive */
- task_lock(tsk);
- parent = task_cgroup(tsk, subsys->subsys_id);
- cg = tsk->cgroups;
- get_css_set(cg);
- task_unlock(tsk);
-
- mutex_unlock(&cgroup_mutex);
-
- /* Now do the VFS work to create a cgroup */
- inode = parent->dentry->d_inode;
-
- /* Hold the parent directory mutex across this operation to
- * stop anyone else deleting the new cgroup */
- mutex_lock(&inode->i_mutex);
- dentry = lookup_one_len(nodename, parent->dentry, strlen(nodename));
- if (IS_ERR(dentry)) {
- printk(KERN_INFO
- "cgroup: Couldn't allocate dentry for %s: %ld\n", nodename,
- PTR_ERR(dentry));
- ret = PTR_ERR(dentry);
- goto out_release;
- }
-
- /* Create the cgroup directory, which also creates the cgroup */
- ret = vfs_mkdir(inode, dentry, 0755);
- child = __d_cgrp(dentry);
- dput(dentry);
- if (ret) {
- printk(KERN_INFO
- "Failed to create cgroup %s: %d\n", nodename,
- ret);
- goto out_release;
- }
-
- /* The cgroup now exists. Retake cgroup_mutex and check
- * that we're still in the same state that we thought we
- * were. */
- mutex_lock(&cgroup_mutex);
- if ((root != subsys->root) ||
- (parent != task_cgroup(tsk, subsys->subsys_id))) {
- /* Aargh, we raced ... */
- mutex_unlock(&inode->i_mutex);
- put_css_set(cg);
-
- deactivate_super(root->sb);
- /* The cgroup is still accessible in the VFS, but
- * we're not going to try to rmdir() it at this
- * point. */
- printk(KERN_INFO
- "Race in cgroup_clone() - leaking cgroup %s\n",
- nodename);
- goto again;
- }
-
- /* do any required auto-setup */
- for_each_subsys(root, ss) {
- if (ss->post_clone)
- ss->post_clone(ss, child);
- }
-
- /* All seems fine. Finish by moving the task into the new cgroup */
- ret = cgroup_attach_task(child, tsk);
- mutex_unlock(&cgroup_mutex);
-
- out_release:
- mutex_unlock(&inode->i_mutex);
-
- mutex_lock(&cgroup_mutex);
- put_css_set(cg);
- mutex_unlock(&cgroup_mutex);
- deactivate_super(root->sb);
- return ret;
-}
-
-/**
* cgroup_is_descendant - see if @cgrp is a descendant of @task's cgrp
* @cgrp: the cgroup in question
* @task: the task in question
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 55b297d78adc..1ceeb049c827 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1802,10 +1802,9 @@ static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
}
/*
- * post_clone() is called at the end of cgroup_clone().
- * 'cgroup' was just created automatically as a result of
- * a cgroup_clone(), and the current task is about to
- * be moved into 'cgroup'.
+ * post_clone() is called during cgroup_create() when the
+ * clone_children mount argument was specified. The cgroup
+ * can not yet have any tasks.
*
* Currently we refuse to set up the cgroup - thereby
* refusing the task to be entered, and as a result refusing
diff --git a/kernel/fork.c b/kernel/fork.c
index 1fa9d940e301..1f84099ecce6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1229,12 +1229,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
if (clone_flags & CLONE_THREAD)
p->tgid = current->tgid;
- if (current->nsproxy != p->nsproxy) {
- retval = ns_cgroup_clone(p, pid);
- if (retval)
- goto bad_fork_free_pid;
- }
-
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
/*
* Clear TID on mm_release()?
diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c
deleted file mode 100644
index 2c98ad94ba0e..000000000000
--- a/kernel/ns_cgroup.c
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * ns_cgroup.c - namespace cgroup subsystem
- *
- * Copyright 2006, 2007 IBM Corp
- */
-
-#include <linux/module.h>
-#include <linux/cgroup.h>
-#include <linux/fs.h>
-#include <linux/proc_fs.h>
-#include <linux/slab.h>
-#include <linux/nsproxy.h>
-
-struct ns_cgroup {
- struct cgroup_subsys_state css;
-};
-
-struct cgroup_subsys ns_subsys;
-
-static inline struct ns_cgroup *cgroup_to_ns(
- struct cgroup *cgroup)
-{
- return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
- struct ns_cgroup, css);
-}
-
-int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
-{
- char name[PROC_NUMBUF];
-
- snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
- return cgroup_clone(task, &ns_subsys, name);
-}
-
-/*
- * Rules:
- * 1. you can only enter a cgroup which is a descendant of your current
- * cgroup
- * 2. you can only place another process into a cgroup if
- * a. you have CAP_SYS_ADMIN
- * b. your cgroup is an ancestor of task's destination cgroup
- * (hence either you are in the same cgroup as task, or in an
- * ancestor cgroup thereof)
- */
-static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
- struct task_struct *task, bool threadgroup)
-{
- if (current != task) {
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
- if (!cgroup_is_descendant(new_cgroup, current))
- return -EPERM;
- }
-
- if (!cgroup_is_descendant(new_cgroup, task))
- return -EPERM;
-
- if (threadgroup) {
- struct task_struct *c;
- rcu_read_lock();
- list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
- if (!cgroup_is_descendant(new_cgroup, c)) {
- rcu_read_unlock();
- return -EPERM;
- }
- }
- rcu_read_unlock();
- }
-
- return 0;
-}
-
-/*
- * Rules: you can only create a cgroup if
- * 1. you are capable(CAP_SYS_ADMIN)
- * 2. the target cgroup is a descendant of your own cgroup
- */
-static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
- struct cgroup *cgroup)
-{
- struct ns_cgroup *ns_cgroup;
-
- if (!capable(CAP_SYS_ADMIN))
- return ERR_PTR(-EPERM);
- if (!cgroup_is_descendant(cgroup, current))
- return ERR_PTR(-EPERM);
- if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
- printk("ns_cgroup can't be created with parent "
- "'clone_children' set.\n");
- return ERR_PTR(-EINVAL);
- }
-
- printk_once("ns_cgroup deprecated: consider using the "
- "'clone_children' flag without the ns_cgroup.\n");
-
- ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
- if (!ns_cgroup)
- return ERR_PTR(-ENOMEM);
- return &ns_cgroup->css;
-}
-
-static void ns_destroy(struct cgroup_subsys *ss,
- struct cgroup *cgroup)
-{
- struct ns_cgroup *ns_cgroup;
-
- ns_cgroup = cgroup_to_ns(cgroup);
- kfree(ns_cgroup);
-}
-
-struct cgroup_subsys ns_subsys = {
- .name = "ns",
- .can_attach = ns_can_attach,
- .create = ns_create,
- .destroy = ns_destroy,
- .subsys_id = ns_subsys_id,
-};
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 5424e37673ed..d6a00f3de15d 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -201,10 +201,6 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
goto out;
}
- err = ns_cgroup_clone(current, task_pid(current));
- if (err)
- put_nsproxy(*new_nsp);
-
out:
return err;
}