Merge branch 'for-3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup changes from Tejun Heo:
"Not too much activity this time around. css_id is finally killed and
a minor update to device_cgroup"
* 'for-3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
device_cgroup: remove can_attach
cgroup: kill css_id
memcg: stop using css id
memcg: fail to create cgroup if the cgroup id is too big
memcg: convert to use cgroup id
memcg: convert to use cgroup_is_descendant()
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 3561d30..39c1d94 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -612,11 +612,6 @@
int subsys_id;
int disabled;
int early_init;
- /*
- * True if this subsys uses ID. ID is not available before cgroup_init()
- * (not available in early_init time.)
- */
- bool use_id;
/*
* If %false, this subsystem is properly hierarchical -
@@ -642,9 +637,6 @@
*/
struct cgroupfs_root *root;
struct list_head sibling;
- /* used when use_id == true */
- struct idr idr;
- spinlock_t id_lock;
/* list of cftype_sets */
struct list_head cftsets;
@@ -875,35 +867,6 @@
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
-/*
- * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
- * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
- * CSS ID is assigned at cgroup allocation (create) automatically
- * and removed when subsys calls free_css_id() function. This is because
- * the lifetime of cgroup_subsys_state is subsys's matter.
- *
- * Looking up and scanning function should be called under rcu_read_lock().
- * Taking cgroup_mutex is not necessary for following calls.
- * But the css returned by this routine can be "not populated yet" or "being
- * destroyed". The caller should check css and cgroup's status.
- */
-
-/*
- * Typically Called at ->destroy(), or somewhere the subsys frees
- * cgroup_subsys_state.
- */
-void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
-
-/* Find a cgroup_subsys_state which has given ID */
-
-struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
-
-/* Returns true if root is ancestor of cg */
-bool css_is_ancestor(struct cgroup_subsys_state *cg,
- const struct cgroup_subsys_state *root);
-
-/* Get id and depth of css */
-unsigned short css_id(struct cgroup_subsys_state *css);
struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,
struct cgroup_subsys *ss);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8bd9cfd..e0839bcd 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -125,38 +125,6 @@
};
/*
- * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
- * cgroup_subsys->use_id != 0.
- */
-#define CSS_ID_MAX (65535)
-struct css_id {
- /*
- * The css to which this ID points. This pointer is set to valid value
- * after cgroup is populated. If cgroup is removed, this will be NULL.
- * This pointer is expected to be RCU-safe because destroy()
- * is called after synchronize_rcu(). But for safe use, css_tryget()
- * should be used for avoiding race.
- */
- struct cgroup_subsys_state __rcu *css;
- /*
- * ID of this css.
- */
- unsigned short id;
- /*
- * Depth in hierarchy which this ID belongs to.
- */
- unsigned short depth;
- /*
- * ID is freed by RCU. (and lookup routine is RCU safe.)
- */
- struct rcu_head rcu_head;
- /*
- * Hierarchy of CSS ID belongs to.
- */
- unsigned short stack[0]; /* Array of Length (depth+1) */
-};
-
-/*
* cgroup_event represents events which userspace want to receive.
*/
struct cgroup_event {
@@ -387,9 +355,6 @@
static struct css_set init_css_set;
static struct cgrp_cset_link init_cgrp_cset_link;
-static int cgroup_init_idr(struct cgroup_subsys *ss,
- struct cgroup_subsys_state *css);
-
/*
* css_set_lock protects the list of css_set objects, and the chain of
* tasks off each css_set. Nests outside task->alloc_lock due to
@@ -841,8 +806,6 @@
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
-static int alloc_css_id(struct cgroup_subsys_state *child_css);
-
static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)
{
struct inode *inode = new_inode(sb);
@@ -4240,21 +4203,6 @@
goto err;
}
}
-
- /* This cgroup is ready now */
- for_each_root_subsys(cgrp->root, ss) {
- struct cgroup_subsys_state *css = cgroup_css(cgrp, ss);
- struct css_id *id = rcu_dereference_protected(css->id, true);
-
- /*
- * Update id->css pointer and make this css visible from
- * CSS ID functions. This pointer will be dereferened
- * from RCU-read-side without locks.
- */
- if (id)
- rcu_assign_pointer(id->css, css);
- }
-
return 0;
err:
cgroup_clear_dir(cgrp, subsys_mask);
@@ -4323,7 +4271,6 @@
css->cgroup = cgrp;
css->ss = ss;
css->flags = 0;
- css->id = NULL;
if (cgrp->parent)
css->parent = cgroup_css(cgrp->parent, ss);
@@ -4455,12 +4402,6 @@
goto err_free_all;
init_css(css, ss, cgrp);
-
- if (ss->use_id) {
- err = alloc_css_id(css);
- if (err)
- goto err_free_all;
- }
}
/*
@@ -4925,12 +4866,6 @@
/* our new subsystem will be attached to the dummy hierarchy. */
init_css(css, ss, cgroup_dummy_top);
- /* init_idr must be after init_css() because it sets css->id. */
- if (ss->use_id) {
- ret = cgroup_init_idr(ss, css);
- if (ret)
- goto err_unload;
- }
/*
* Now we need to entangle the css into the existing css_sets. unlike
@@ -4996,9 +4931,6 @@
offline_css(cgroup_css(cgroup_dummy_top, ss));
- if (ss->use_id)
- idr_destroy(&ss->idr);
-
/* deassign the subsys_id */
cgroup_subsys[ss->subsys_id] = NULL;
@@ -5025,8 +4957,7 @@
/*
* remove subsystem's css from the cgroup_dummy_top and free it -
* need to free before marking as null because ss->css_free needs
- * the cgrp->subsys pointer to find their state. note that this
- * also takes care of freeing the css_id.
+ * the cgrp->subsys pointer to find their state.
*/
ss->css_free(cgroup_css(cgroup_dummy_top, ss));
RCU_INIT_POINTER(cgroup_dummy_top->subsys[ss->subsys_id], NULL);
@@ -5097,8 +5028,6 @@
for_each_builtin_subsys(ss, i) {
if (!ss->early_init)
cgroup_init_subsys(ss);
- if (ss->use_id)
- cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]);
}
/* allocate id for the dummy hierarchy */
@@ -5518,181 +5447,6 @@
}
__setup("cgroup_disable=", cgroup_disable);
-/*
- * Functons for CSS ID.
- */
-
-/* to get ID other than 0, this should be called when !cgroup_is_dead() */
-unsigned short css_id(struct cgroup_subsys_state *css)
-{
- struct css_id *cssid;
-
- /*
- * This css_id() can return correct value when somone has refcnt
- * on this or this is under rcu_read_lock(). Once css->id is allocated,
- * it's unchanged until freed.
- */
- cssid = rcu_dereference_raw(css->id);
-
- if (cssid)
- return cssid->id;
- return 0;
-}
-EXPORT_SYMBOL_GPL(css_id);
-
-/**
- * css_is_ancestor - test "root" css is an ancestor of "child"
- * @child: the css to be tested.
- * @root: the css supporsed to be an ancestor of the child.
- *
- * Returns true if "root" is an ancestor of "child" in its hierarchy. Because
- * this function reads css->id, the caller must hold rcu_read_lock().
- * But, considering usual usage, the csses should be valid objects after test.
- * Assuming that the caller will do some action to the child if this returns
- * returns true, the caller must take "child";s reference count.
- * If "child" is valid object and this returns true, "root" is valid, too.
- */
-
-bool css_is_ancestor(struct cgroup_subsys_state *child,
- const struct cgroup_subsys_state *root)
-{
- struct css_id *child_id;
- struct css_id *root_id;
-
- child_id = rcu_dereference(child->id);
- if (!child_id)
- return false;
- root_id = rcu_dereference(root->id);
- if (!root_id)
- return false;
- if (child_id->depth < root_id->depth)
- return false;
- if (child_id->stack[root_id->depth] != root_id->id)
- return false;
- return true;
-}
-
-void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css)
-{
- struct css_id *id = rcu_dereference_protected(css->id, true);
-
- /* When this is called before css_id initialization, id can be NULL */
- if (!id)
- return;
-
- BUG_ON(!ss->use_id);
-
- rcu_assign_pointer(id->css, NULL);
- rcu_assign_pointer(css->id, NULL);
- spin_lock(&ss->id_lock);
- idr_remove(&ss->idr, id->id);
- spin_unlock(&ss->id_lock);
- kfree_rcu(id, rcu_head);
-}
-EXPORT_SYMBOL_GPL(free_css_id);
-
-/*
- * This is called by init or create(). Then, calls to this function are
- * always serialized (By cgroup_mutex() at create()).
- */
-
-static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth)
-{
- struct css_id *newid;
- int ret, size;
-
- BUG_ON(!ss->use_id);
-
- size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1);
- newid = kzalloc(size, GFP_KERNEL);
- if (!newid)
- return ERR_PTR(-ENOMEM);
-
- idr_preload(GFP_KERNEL);
- spin_lock(&ss->id_lock);
- /* Don't use 0. allocates an ID of 1-65535 */
- ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT);
- spin_unlock(&ss->id_lock);
- idr_preload_end();
-
- /* Returns error when there are no free spaces for new ID.*/
- if (ret < 0)
- goto err_out;
-
- newid->id = ret;
- newid->depth = depth;
- return newid;
-err_out:
- kfree(newid);
- return ERR_PTR(ret);
-
-}
-
-static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss,
- struct cgroup_subsys_state *rootcss)
-{
- struct css_id *newid;
-
- spin_lock_init(&ss->id_lock);
- idr_init(&ss->idr);
-
- newid = get_new_cssid(ss, 0);
- if (IS_ERR(newid))
- return PTR_ERR(newid);
-
- newid->stack[0] = newid->id;
- RCU_INIT_POINTER(newid->css, rootcss);
- RCU_INIT_POINTER(rootcss->id, newid);
- return 0;
-}
-
-static int alloc_css_id(struct cgroup_subsys_state *child_css)
-{
- struct cgroup_subsys_state *parent_css = css_parent(child_css);
- struct css_id *child_id, *parent_id;
- int i, depth;
-
- parent_id = rcu_dereference_protected(parent_css->id, true);
- depth = parent_id->depth + 1;
-
- child_id = get_new_cssid(child_css->ss, depth);
- if (IS_ERR(child_id))
- return PTR_ERR(child_id);
-
- for (i = 0; i < depth; i++)
- child_id->stack[i] = parent_id->stack[i];
- child_id->stack[depth] = child_id->id;
- /*
- * child_id->css pointer will be set after this cgroup is available
- * see cgroup_populate_dir()
- */
- rcu_assign_pointer(child_css->id, child_id);
-
- return 0;
-}
-
-/**
- * css_lookup - lookup css by id
- * @ss: cgroup subsys to be looked into.
- * @id: the id
- *
- * Returns pointer to cgroup_subsys_state if there is valid one with id.
- * NULL if not. Should be called under rcu_read_lock()
- */
-struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id)
-{
- struct css_id *cssid = NULL;
-
- BUG_ON(!ss->use_id);
- cssid = idr_find(&ss->idr, id);
-
- if (unlikely(!cssid))
- return NULL;
-
- return rcu_dereference(cssid->css);
-}
-EXPORT_SYMBOL_GPL(css_lookup);
-
/**
* css_from_dir - get corresponding css from the dentry of a cgroup dir
* @dentry: directory dentry of interest
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 13b9d0f2..7968209 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -499,6 +499,29 @@
return (memcg == root_mem_cgroup);
}
+/*
+ * We restrict the id in the range of [1, 65535], so it can fit into
+ * an unsigned short.
+ */
+#define MEM_CGROUP_ID_MAX USHRT_MAX
+
+static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
+{
+ /*
+ * The ID of the root cgroup is 0, but memcg treat 0 as an
+ * invalid ID, so we return (cgroup_id + 1).
+ */
+ return memcg->css.cgroup->id + 1;
+}
+
+static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+ struct cgroup_subsys_state *css;
+
+ css = css_from_id(id - 1, &mem_cgroup_subsys);
+ return mem_cgroup_from_css(css);
+}
+
/* Writing them here to avoid exposing memcg's inner layout */
#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
@@ -570,16 +593,11 @@
#ifdef CONFIG_MEMCG_KMEM
/*
* This will be the memcg's index in each cache's ->memcg_params->memcg_caches.
- * There are two main reasons for not using the css_id for this:
- * 1) this works better in sparse environments, where we have a lot of memcgs,
- * but only a few kmem-limited. Or also, if we have, for instance, 200
- * memcgs, and none but the 200th is kmem-limited, we'd have to have a
- * 200 entry array for that.
- *
- * 2) In order not to violate the cgroup API, we would like to do all memory
- * allocation in ->create(). At that point, we haven't yet allocated the
- * css_id. Having a separate index prevents us from messing with the cgroup
- * core for this
+ * The main reason for not using cgroup id for this:
+ * this works better in sparse environments, where we have a lot of memcgs,
+ * but only a few kmem-limited. Or also, if we have, for instance, 200
+ * memcgs, and none but the 200th is kmem-limited, we'd have to have a
+ * 200 entry array for that.
*
* The current size of the caches array is stored in
* memcg_limited_groups_array_size. It will double each time we have to
@@ -594,14 +612,14 @@
* cgroups is a reasonable guess. In the future, it could be a parameter or
* tunable, but that is strictly not necessary.
*
- * MAX_SIZE should be as large as the number of css_ids. Ideally, we could get
+ * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
* this constant directly from cgroup, but it is understandable that this is
* better kept as an internal representation in cgroup.c. In any case, the
- * css_id space is not getting any smaller, and we don't have to necessarily
+ * cgrp_id space is not getting any smaller, and we don't have to necessarily
* increase ours as well if it increases.
*/
#define MEMCG_CACHES_MIN_SIZE 4
-#define MEMCG_CACHES_MAX_SIZE 65535
+#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX
/*
* A lot of the calls to the cache allocation functions are expected to be
@@ -1408,7 +1426,7 @@
return true;
if (!root_memcg->use_hierarchy || !memcg)
return false;
- return css_is_ancestor(&memcg->css, &root_memcg->css);
+ return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
}
static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
@@ -2826,15 +2844,10 @@
*/
static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
{
- struct cgroup_subsys_state *css;
-
/* ID 0 is unused ID */
if (!id)
return NULL;
- css = css_lookup(&mem_cgroup_subsys, id);
- if (!css)
- return NULL;
- return mem_cgroup_from_css(css);
+ return mem_cgroup_from_id(id);
}
struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
@@ -4350,7 +4363,7 @@
* css_get() was called in uncharge().
*/
if (do_swap_account && swapout && memcg)
- swap_cgroup_record(ent, css_id(&memcg->css));
+ swap_cgroup_record(ent, mem_cgroup_id(memcg));
}
#endif
@@ -4402,8 +4415,8 @@
{
unsigned short old_id, new_id;
- old_id = css_id(&from->css);
- new_id = css_id(&to->css);
+ old_id = mem_cgroup_id(from);
+ new_id = mem_cgroup_id(to);
if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
mem_cgroup_swap_statistics(from, false);
@@ -6166,7 +6179,6 @@
size_t size = memcg_size();
mem_cgroup_remove_from_trees(memcg);
- free_css_id(&mem_cgroup_subsys, &memcg->css);
for_each_node(node)
free_mem_cgroup_per_zone_info(memcg, node);
@@ -6269,6 +6281,9 @@
struct mem_cgroup *parent = mem_cgroup_from_css(css_parent(css));
int error = 0;
+ if (css->cgroup->id > MEM_CGROUP_ID_MAX)
+ return -ENOSPC;
+
if (!parent)
return 0;
@@ -6540,7 +6555,7 @@
}
/* There is a swap entry and a page doesn't exist or isn't charged */
if (ent.val && !ret &&
- css_id(&mc.from->css) == lookup_swap_cgroup_id(ent)) {
+ mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
ret = MC_TARGET_SWAP;
if (target)
target->ent = ent;
@@ -6960,7 +6975,6 @@
.bind = mem_cgroup_bind,
.base_cftypes = mem_cgroup_files,
.early_init = 0,
- .use_id = 1,
};
#ifdef CONFIG_MEMCG_SWAP
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index c123628..7c2a0a7 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -63,16 +63,6 @@
struct cgroup_subsys devices_subsys;
-static int devcgroup_can_attach(struct cgroup_subsys_state *new_css,
- struct cgroup_taskset *set)
-{
- struct task_struct *task = cgroup_taskset_first(set);
-
- if (current != task && !capable(CAP_SYS_ADMIN))
- return -EPERM;
- return 0;
-}
-
/*
* called under devcgroup_mutex
*/
@@ -697,7 +687,6 @@
struct cgroup_subsys devices_subsys = {
.name = "devices",
- .can_attach = devcgroup_can_attach,
.css_alloc = devcgroup_css_alloc,
.css_free = devcgroup_css_free,
.css_online = devcgroup_online,
