diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 262 |
1 files changed, 7 insertions, 255 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2418b6e71a85..e0839bcd48c8 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -125,38 +125,6 @@ struct cfent { }; /* - * 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 @@ struct cgrp_cset_link { 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 @@ static struct backing_dev_info cgroup_backing_dev_info = { .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); @@ -2039,7 +2002,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, /* @tsk either already exited or can't exit until the end */ if (tsk->flags & PF_EXITING) - continue; + goto next; /* as per above, nr_threads may decrease, but not increase. */ BUG_ON(i >= group_size); @@ -2047,7 +2010,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, ent.cgrp = task_cgroup_from_root(tsk, root); /* nothing to do if this task is already in the cgroup */ if (ent.cgrp == cgrp) - continue; + goto next; /* * saying GFP_ATOMIC has no effect here because we did prealloc * earlier, but it's good form to communicate our expectations. @@ -2055,7 +2018,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, retval = flex_array_put(group, i, &ent, GFP_ATOMIC); BUG_ON(retval != 0); i++; - + next: if (!threadgroup) break; } while_each_thread(leader, tsk); @@ -3188,11 +3151,9 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, WARN_ON_ONCE(!rcu_read_lock_held()); - /* if first iteration, visit the leftmost descendant */ - if (!pos) { - next = css_leftmost_descendant(root); - return next != root ? next : NULL; - } + /* if first iteration, visit leftmost descendant which may be @root */ + if (!pos) + return css_leftmost_descendant(root); /* if we visited @root, we're done */ if (pos == root) @@ -4242,21 +4203,6 @@ static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) 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); @@ -4325,7 +4271,6 @@ static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss, css->cgroup = cgrp; css->ss = ss; css->flags = 0; - css->id = NULL; if (cgrp->parent) css->parent = cgroup_css(cgrp->parent, ss); @@ -4457,12 +4402,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, goto err_free_all; init_css(css, ss, cgrp); - - if (ss->use_id) { - err = alloc_css_id(css); - if (err) - goto err_free_all; - } } /* @@ -4927,12 +4866,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) /* 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 @@ -4998,9 +4931,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) 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; @@ -5027,8 +4957,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) /* * 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); @@ -5099,8 +5028,6 @@ int __init cgroup_init(void) 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 */ @@ -5520,181 +5447,6 @@ static int __init cgroup_disable(char *str) } __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 |