![Tejun Heo](/assets/img/avatar_default.png)
pids controller is completely broken in that it uncharges when a task exits allowing zombies to escape resource control. With the recent updates, cgroup core now maintains cgroup association till task free and pids controller can be fixed by uncharging on free instead of exit. This patch adds cgroup_subsys->free() method and update pids controller to use it instead of ->exit() for uncharging. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Aleksa Sarai <cyphar@cyphar.com>
532 lines
16 KiB
C
532 lines
16 KiB
C
/*
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* linux/cgroup-defs.h - basic definitions for cgroup
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*
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* This file provides basic type and interface. Include this file directly
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* only if necessary to avoid cyclic dependencies.
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*/
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#ifndef _LINUX_CGROUP_DEFS_H
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#define _LINUX_CGROUP_DEFS_H
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#include <linux/limits.h>
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#include <linux/list.h>
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#include <linux/idr.h>
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#include <linux/wait.h>
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#include <linux/mutex.h>
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#include <linux/rcupdate.h>
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#include <linux/percpu-refcount.h>
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#include <linux/percpu-rwsem.h>
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#include <linux/workqueue.h>
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#ifdef CONFIG_CGROUPS
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struct cgroup;
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struct cgroup_root;
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struct cgroup_subsys;
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struct cgroup_taskset;
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struct kernfs_node;
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struct kernfs_ops;
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struct kernfs_open_file;
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struct seq_file;
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#define MAX_CGROUP_TYPE_NAMELEN 32
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#define MAX_CGROUP_ROOT_NAMELEN 64
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#define MAX_CFTYPE_NAME 64
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/* define the enumeration of all cgroup subsystems */
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#define SUBSYS(_x) _x ## _cgrp_id,
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#define SUBSYS_TAG(_t) CGROUP_ ## _t, \
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__unused_tag_ ## _t = CGROUP_ ## _t - 1,
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enum cgroup_subsys_id {
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#include <linux/cgroup_subsys.h>
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CGROUP_SUBSYS_COUNT,
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};
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#undef SUBSYS_TAG
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#undef SUBSYS
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#define CGROUP_CANFORK_COUNT (CGROUP_CANFORK_END - CGROUP_CANFORK_START)
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/* bits in struct cgroup_subsys_state flags field */
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enum {
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CSS_NO_REF = (1 << 0), /* no reference counting for this css */
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CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
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CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
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};
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/* bits in struct cgroup flags field */
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enum {
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/* Control Group requires release notifications to userspace */
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CGRP_NOTIFY_ON_RELEASE,
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/*
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* Clone the parent's configuration when creating a new child
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* cpuset cgroup. For historical reasons, this option can be
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* specified at mount time and thus is implemented here.
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*/
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CGRP_CPUSET_CLONE_CHILDREN,
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};
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/* cgroup_root->flags */
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enum {
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CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
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CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
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CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
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};
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/* cftype->flags */
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enum {
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CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
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CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
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CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
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CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
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/* internal flags, do not use outside cgroup core proper */
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__CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
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__CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
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};
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/*
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* cgroup_file is the handle for a file instance created in a cgroup which
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* is used, for example, to generate file changed notifications. This can
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* be obtained by setting cftype->file_offset.
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*/
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struct cgroup_file {
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/* do not access any fields from outside cgroup core */
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struct list_head node; /* anchored at css->files */
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struct kernfs_node *kn;
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};
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/*
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* Per-subsystem/per-cgroup state maintained by the system. This is the
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* fundamental structural building block that controllers deal with.
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*
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* Fields marked with "PI:" are public and immutable and may be accessed
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* directly without synchronization.
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*/
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struct cgroup_subsys_state {
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/* PI: the cgroup that this css is attached to */
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struct cgroup *cgroup;
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/* PI: the cgroup subsystem that this css is attached to */
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struct cgroup_subsys *ss;
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/* reference count - access via css_[try]get() and css_put() */
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struct percpu_ref refcnt;
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/* PI: the parent css */
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struct cgroup_subsys_state *parent;
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/* siblings list anchored at the parent's ->children */
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struct list_head sibling;
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struct list_head children;
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/*
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* PI: Subsys-unique ID. 0 is unused and root is always 1. The
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* matching css can be looked up using css_from_id().
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*/
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int id;
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unsigned int flags;
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/*
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* Monotonically increasing unique serial number which defines a
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* uniform order among all csses. It's guaranteed that all
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* ->children lists are in the ascending order of ->serial_nr and
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* used to allow interrupting and resuming iterations.
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*/
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u64 serial_nr;
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/* all cgroup_files associated with this css */
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struct list_head files;
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/* percpu_ref killing and RCU release */
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struct rcu_head rcu_head;
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struct work_struct destroy_work;
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};
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/*
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* A css_set is a structure holding pointers to a set of
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* cgroup_subsys_state objects. This saves space in the task struct
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* object and speeds up fork()/exit(), since a single inc/dec and a
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* list_add()/del() can bump the reference count on the entire cgroup
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* set for a task.
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*/
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struct css_set {
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/* Reference count */
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atomic_t refcount;
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/*
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* List running through all cgroup groups in the same hash
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* slot. Protected by css_set_lock
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*/
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struct hlist_node hlist;
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/*
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* Lists running through all tasks using this cgroup group.
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* mg_tasks lists tasks which belong to this cset but are in the
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* process of being migrated out or in. Protected by
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* css_set_rwsem, but, during migration, once tasks are moved to
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* mg_tasks, it can be read safely while holding cgroup_mutex.
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*/
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struct list_head tasks;
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struct list_head mg_tasks;
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/*
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* List of cgrp_cset_links pointing at cgroups referenced from this
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* css_set. Protected by css_set_lock.
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*/
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struct list_head cgrp_links;
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/* the default cgroup associated with this css_set */
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struct cgroup *dfl_cgrp;
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/*
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* Set of subsystem states, one for each subsystem. This array is
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* immutable after creation apart from the init_css_set during
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* subsystem registration (at boot time).
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*/
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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/*
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* List of csets participating in the on-going migration either as
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* source or destination. Protected by cgroup_mutex.
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*/
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struct list_head mg_preload_node;
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struct list_head mg_node;
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/*
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* If this cset is acting as the source of migration the following
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* two fields are set. mg_src_cgrp is the source cgroup of the
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* on-going migration and mg_dst_cset is the destination cset the
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* target tasks on this cset should be migrated to. Protected by
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* cgroup_mutex.
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*/
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struct cgroup *mg_src_cgrp;
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struct css_set *mg_dst_cset;
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/*
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* On the default hierarhcy, ->subsys[ssid] may point to a css
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* attached to an ancestor instead of the cgroup this css_set is
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* associated with. The following node is anchored at
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* ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
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* iterate through all css's attached to a given cgroup.
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*/
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struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
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/* all css_task_iters currently walking this cset */
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struct list_head task_iters;
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/* For RCU-protected deletion */
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struct rcu_head rcu_head;
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};
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struct cgroup {
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/* self css with NULL ->ss, points back to this cgroup */
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struct cgroup_subsys_state self;
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unsigned long flags; /* "unsigned long" so bitops work */
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/*
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* idr allocated in-hierarchy ID.
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*
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* ID 0 is not used, the ID of the root cgroup is always 1, and a
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* new cgroup will be assigned with a smallest available ID.
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*
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* Allocating/Removing ID must be protected by cgroup_mutex.
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*/
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int id;
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/*
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* Each non-empty css_set associated with this cgroup contributes
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* one to populated_cnt. All children with non-zero popuplated_cnt
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* of their own contribute one. The count is zero iff there's no
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* task in this cgroup or its subtree.
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*/
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int populated_cnt;
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struct kernfs_node *kn; /* cgroup kernfs entry */
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struct cgroup_file procs_file; /* handle for "cgroup.procs" */
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struct cgroup_file events_file; /* handle for "cgroup.events" */
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/*
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* The bitmask of subsystems enabled on the child cgroups.
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* ->subtree_control is the one configured through
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* "cgroup.subtree_control" while ->child_subsys_mask is the
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* effective one which may have more subsystems enabled.
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* Controller knobs are made available iff it's enabled in
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* ->subtree_control.
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*/
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unsigned int subtree_control;
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unsigned int child_subsys_mask;
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/* Private pointers for each registered subsystem */
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struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
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struct cgroup_root *root;
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/*
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* List of cgrp_cset_links pointing at css_sets with tasks in this
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* cgroup. Protected by css_set_lock.
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*/
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struct list_head cset_links;
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/*
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* On the default hierarchy, a css_set for a cgroup with some
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* susbsys disabled will point to css's which are associated with
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* the closest ancestor which has the subsys enabled. The
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* following lists all css_sets which point to this cgroup's css
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* for the given subsystem.
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*/
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struct list_head e_csets[CGROUP_SUBSYS_COUNT];
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/*
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* list of pidlists, up to two for each namespace (one for procs, one
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* for tasks); created on demand.
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*/
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struct list_head pidlists;
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struct mutex pidlist_mutex;
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/* used to wait for offlining of csses */
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wait_queue_head_t offline_waitq;
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/* used to schedule release agent */
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struct work_struct release_agent_work;
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};
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/*
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* A cgroup_root represents the root of a cgroup hierarchy, and may be
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* associated with a kernfs_root to form an active hierarchy. This is
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* internal to cgroup core. Don't access directly from controllers.
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*/
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struct cgroup_root {
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struct kernfs_root *kf_root;
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/* The bitmask of subsystems attached to this hierarchy */
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unsigned int subsys_mask;
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/* Unique id for this hierarchy. */
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int hierarchy_id;
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/* The root cgroup. Root is destroyed on its release. */
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struct cgroup cgrp;
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/* Number of cgroups in the hierarchy, used only for /proc/cgroups */
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atomic_t nr_cgrps;
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/* A list running through the active hierarchies */
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struct list_head root_list;
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/* Hierarchy-specific flags */
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unsigned int flags;
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/* IDs for cgroups in this hierarchy */
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struct idr cgroup_idr;
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/* The path to use for release notifications. */
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char release_agent_path[PATH_MAX];
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/* The name for this hierarchy - may be empty */
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char name[MAX_CGROUP_ROOT_NAMELEN];
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};
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/*
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* struct cftype: handler definitions for cgroup control files
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*
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* When reading/writing to a file:
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* - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
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* - the 'cftype' of the file is file->f_path.dentry->d_fsdata
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*/
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struct cftype {
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/*
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* By convention, the name should begin with the name of the
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* subsystem, followed by a period. Zero length string indicates
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* end of cftype array.
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*/
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char name[MAX_CFTYPE_NAME];
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unsigned long private;
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/*
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* The maximum length of string, excluding trailing nul, that can
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* be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
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*/
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size_t max_write_len;
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/* CFTYPE_* flags */
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unsigned int flags;
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/*
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* If non-zero, should contain the offset from the start of css to
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* a struct cgroup_file field. cgroup will record the handle of
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* the created file into it. The recorded handle can be used as
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* long as the containing css remains accessible.
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*/
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unsigned int file_offset;
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/*
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* Fields used for internal bookkeeping. Initialized automatically
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* during registration.
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*/
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struct cgroup_subsys *ss; /* NULL for cgroup core files */
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struct list_head node; /* anchored at ss->cfts */
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struct kernfs_ops *kf_ops;
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/*
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* read_u64() is a shortcut for the common case of returning a
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* single integer. Use it in place of read()
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*/
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u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
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/*
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* read_s64() is a signed version of read_u64()
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*/
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s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
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/* generic seq_file read interface */
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int (*seq_show)(struct seq_file *sf, void *v);
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/* optional ops, implement all or none */
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void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
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void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
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void (*seq_stop)(struct seq_file *sf, void *v);
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/*
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* write_u64() is a shortcut for the common case of accepting
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* a single integer (as parsed by simple_strtoull) from
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* userspace. Use in place of write(); return 0 or error.
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*/
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int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
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u64 val);
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/*
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* write_s64() is a signed version of write_u64()
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*/
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int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
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s64 val);
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/*
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* write() is the generic write callback which maps directly to
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* kernfs write operation and overrides all other operations.
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* Maximum write size is determined by ->max_write_len. Use
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* of_css/cft() to access the associated css and cft.
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*/
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ssize_t (*write)(struct kernfs_open_file *of,
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char *buf, size_t nbytes, loff_t off);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lock_class_key lockdep_key;
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#endif
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};
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/*
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* Control Group subsystem type.
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* See Documentation/cgroups/cgroups.txt for details
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*/
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struct cgroup_subsys {
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struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
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int (*css_online)(struct cgroup_subsys_state *css);
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void (*css_offline)(struct cgroup_subsys_state *css);
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void (*css_released)(struct cgroup_subsys_state *css);
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void (*css_free)(struct cgroup_subsys_state *css);
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void (*css_reset)(struct cgroup_subsys_state *css);
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void (*css_e_css_changed)(struct cgroup_subsys_state *css);
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int (*can_attach)(struct cgroup_subsys_state *css,
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struct cgroup_taskset *tset);
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void (*cancel_attach)(struct cgroup_subsys_state *css,
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struct cgroup_taskset *tset);
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void (*attach)(struct cgroup_subsys_state *css,
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struct cgroup_taskset *tset);
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int (*can_fork)(struct task_struct *task, void **priv_p);
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void (*cancel_fork)(struct task_struct *task, void *priv);
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void (*fork)(struct task_struct *task, void *priv);
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void (*exit)(struct task_struct *task);
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void (*free)(struct task_struct *task);
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void (*bind)(struct cgroup_subsys_state *root_css);
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int early_init;
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/*
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* If %false, this subsystem is properly hierarchical -
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* configuration, resource accounting and restriction on a parent
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* cgroup cover those of its children. If %true, hierarchy support
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* is broken in some ways - some subsystems ignore hierarchy
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* completely while others are only implemented half-way.
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*
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* It's now disallowed to create nested cgroups if the subsystem is
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* broken and cgroup core will emit a warning message on such
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* cases. Eventually, all subsystems will be made properly
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* hierarchical and this will go away.
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*/
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bool broken_hierarchy;
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bool warned_broken_hierarchy;
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/* the following two fields are initialized automtically during boot */
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int id;
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const char *name;
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/* optional, initialized automatically during boot if not set */
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const char *legacy_name;
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/* link to parent, protected by cgroup_lock() */
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struct cgroup_root *root;
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/* idr for css->id */
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struct idr css_idr;
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/*
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* List of cftypes. Each entry is the first entry of an array
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* terminated by zero length name.
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*/
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struct list_head cfts;
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/*
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* Base cftypes which are automatically registered. The two can
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* point to the same array.
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*/
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struct cftype *dfl_cftypes; /* for the default hierarchy */
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struct cftype *legacy_cftypes; /* for the legacy hierarchies */
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/*
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* A subsystem may depend on other subsystems. When such subsystem
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* is enabled on a cgroup, the depended-upon subsystems are enabled
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* together if available. Subsystems enabled due to dependency are
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* not visible to userland until explicitly enabled. The following
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* specifies the mask of subsystems that this one depends on.
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*/
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unsigned int depends_on;
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};
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extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
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/**
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* cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
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* @tsk: target task
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*
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* Called from threadgroup_change_begin() and allows cgroup operations to
|
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* synchronize against threadgroup changes using a percpu_rw_semaphore.
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*/
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static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
|
|
{
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|
percpu_down_read(&cgroup_threadgroup_rwsem);
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|
}
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|
|
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/**
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|
* cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
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|
* @tsk: target task
|
|
*
|
|
* Called from threadgroup_change_end(). Counterpart of
|
|
* cgroup_threadcgroup_change_begin().
|
|
*/
|
|
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
|
|
{
|
|
percpu_up_read(&cgroup_threadgroup_rwsem);
|
|
}
|
|
|
|
#else /* CONFIG_CGROUPS */
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|
|
|
#define CGROUP_CANFORK_COUNT 0
|
|
#define CGROUP_SUBSYS_COUNT 0
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|
|
|
static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
|
|
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
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|
|
|
#endif /* CONFIG_CGROUPS */
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|
|
|
#endif /* _LINUX_CGROUP_DEFS_H */
|