On Wed 24-07-13 18:03:36, Li Zefan wrote: > The only user of css_id was memcg, and it has been convered to use > cgroup->id, so kill css_id. > > Signed-off-by: Li Zefan <[email protected]>
Nice Reviewed-by: Michal Hocko <[email protected]> > --- > include/linux/cgroup.h | 37 -------- > kernel/cgroup.c | 252 > +------------------------------------------------ > 2 files changed, 1 insertion(+), 288 deletions(-) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index e8eb361..ec8c380 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -599,11 +599,6 @@ struct cgroup_subsys { > 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 - > @@ -629,9 +624,6 @@ struct cgroup_subsys { > */ > 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; > @@ -858,35 +850,6 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan); > 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 *cgroup_css_from_dir(struct file *f, int id); > > #else /* !CONFIG_CGROUPS */ > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 9b27775..4333cb7 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -123,38 +123,6 @@ 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 { > @@ -364,9 +332,6 @@ 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 cgroup_iter_start() */ > @@ -815,9 +780,6 @@ static struct backing_dev_info cgroup_backing_dev_info = { > .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, > }; > > -static int alloc_css_id(struct cgroup_subsys *ss, > - struct cgroup *parent, struct cgroup *child); > - > static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) > { > struct inode *inode = new_inode(sb); > @@ -4160,20 +4122,6 @@ static int cgroup_populate_dir(struct cgroup *cgrp, > unsigned long subsys_mask) > } > } > > - /* This cgroup is ready now */ > - for_each_root_subsys(cgrp->root, ss) { > - struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; > - 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); > @@ -4202,7 +4150,6 @@ static void init_cgroup_css(struct cgroup_subsys_state > *css, > { > css->cgroup = cgrp; > css->flags = 0; > - css->id = NULL; > if (cgrp == cgroup_dummy_top) > css->flags |= CSS_ROOT; > BUG_ON(cgrp->subsys[ss->subsys_id]); > @@ -4331,12 +4278,6 @@ static long cgroup_create(struct cgroup *parent, > struct dentry *dentry, > goto err_free_all; > > init_cgroup_css(css, ss, cgrp); > - > - if (ss->use_id) { > - err = alloc_css_id(ss, parent, cgrp); > - if (err) > - goto err_free_all; > - } > } > > /* > @@ -4741,12 +4682,6 @@ int __init_or_module cgroup_load_subsys(struct > cgroup_subsys *ss) > > /* our new subsystem will be attached to the dummy hierarchy. */ > init_cgroup_css(css, ss, cgroup_dummy_top); > - /* init_idr must be after init_cgroup_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 > @@ -4812,9 +4747,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) > > offline_css(ss, cgroup_dummy_top); > > - if (ss->use_id) > - idr_destroy(&ss->idr); > - > /* deassign the subsys_id */ > cgroup_subsys[ss->subsys_id] = NULL; > > @@ -4841,8 +4773,7 @@ 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_dummy_top); > cgroup_dummy_top->subsys[ss->subsys_id] = NULL; > @@ -4913,8 +4844,6 @@ 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 */ > @@ -5335,185 +5264,6 @@ 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 *ss, struct cgroup *parent, > - struct cgroup *child) > -{ > - int subsys_id, i, depth = 0; > - struct cgroup_subsys_state *parent_css, *child_css; > - struct css_id *child_id, *parent_id; > - > - subsys_id = ss->subsys_id; > - parent_css = parent->subsys[subsys_id]; > - child_css = child->subsys[subsys_id]; > - parent_id = rcu_dereference_protected(parent_css->id, true); > - depth = parent_id->depth + 1; > - > - child_id = get_new_cssid(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); > - > -/* > * get corresponding css from file open on cgroupfs directory > */ > struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) > -- > 1.8.0.2 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"[email protected]";> [email protected] </a> -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
