cgroup: kill css_id
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 <lizefan@huwei.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org>hifive-unleashed-5.1
Li Zefan
Tejun Heo
parent
b862783594
commit
2ff2a7d03b
|
|
@ -612,11 +612,6 @@ 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 -
|
||||
|
|
@ -642,9 +637,6 @@ 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;
|
||||
|
|
@ -875,35 +867,6 @@ int css_scan_tasks(struct cgroup_subsys_state *css,
|
|||
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);
|
||||
|
||||
|
|
|
|||
248
kernel/cgroup.c
248
kernel/cgroup.c
|
|
@ -124,38 +124,6 @@ struct cfent {
|
|||
struct simple_xattrs xattrs;
|
||||
};
|
||||
|
||||
/*
|
||||
* 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.
|
||||
*/
|
||||
|
|
@ -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);
|
||||
|
|
@ -4242,21 +4205,6 @@ 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 +4273,6 @@ 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 +4404,6 @@ 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 +4868,6 @@ 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 +4933,6 @@ 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 +4959,7 @@ 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 +5030,6 @@ 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 +5449,6 @@ 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
|
||||
|
|
|
|||
Loading…
Reference in New Issue