3. Structural Constraints
3-1. Top-down
3-2. No internal tasks
-4. Other Changes
- 4-1. [Un]populated Notification
- 4-2. Other Core Changes
- 4-3. Per-Controller Changes
- 4-3-1. blkio
- 4-3-2. cpuset
- 4-3-3. memory
-5. Planned Changes
- 5-1. CAP for resource control
+4. Delegation
+ 4-1. Model of delegation
+ 4-2. Common ancestor rule
+5. Other Changes
+ 5-1. [Un]populated Notification
+ 5-2. Other Core Changes
+ 5-3. Per-Controller Changes
+ 5-3-1. blkio
+ 5-3-2. cpuset
+ 5-3-3. memory
+6. Planned Changes
+ 6-1. CAP for resource control
1. Background
before enabling controllers in its "cgroup.subtree_control" file.
-4. Other Changes
+4. Delegation
-4-1. [Un]populated Notification
+4-1. Model of delegation
+
+A cgroup can be delegated to a less privileged user by granting write
+access of the directory and its "cgroup.procs" file to the user. Note
+that the resource control knobs in a given directory concern the
+resources of the parent and thus must not be delegated along with the
+directory.
+
+Once delegated, the user can build sub-hierarchy under the directory,
+organize processes as it sees fit and further distribute the resources
+it got from the parent. The limits and other settings of all resource
+controllers are hierarchical and regardless of what happens in the
+delegated sub-hierarchy, nothing can escape the resource restrictions
+imposed by the parent.
+
+Currently, cgroup doesn't impose any restrictions on the number of
+cgroups in or nesting depth of a delegated sub-hierarchy; however,
+this may in the future be limited explicitly.
+
+
+4-2. Common ancestor rule
+
+On the unified hierarchy, to write to a "cgroup.procs" file, in
+addition to the usual write permission to the file and uid match, the
+writer must also have write access to the "cgroup.procs" file of the
+common ancestor of the source and destination cgroups. This prevents
+delegatees from smuggling processes across disjoint sub-hierarchies.
+
+Let's say cgroups C0 and C1 have been delegated to user U0 who created
+C00, C01 under C0 and C10 under C1 as follows.
+
+ ~~~~~~~~~~~~~ - C0 - C00
+ ~ cgroup ~ \ C01
+ ~ hierarchy ~
+ ~~~~~~~~~~~~~ - C1 - C10
+
+C0 and C1 are separate entities in terms of resource distribution
+regardless of their relative positions in the hierarchy. The
+resources the processes under C0 are entitled to are controlled by
+C0's ancestors and may be completely different from C1. It's clear
+that the intention of delegating C0 to U0 is allowing U0 to organize
+the processes under C0 and further control the distribution of C0's
+resources.
+
+On traditional hierarchies, if a task has write access to "tasks" or
+"cgroup.procs" file of a cgroup and its uid agrees with the target, it
+can move the target to the cgroup. In the above example, U0 will not
+only be able to move processes in each sub-hierarchy but also across
+the two sub-hierarchies, effectively allowing it to violate the
+organizational and resource restrictions implied by the hierarchical
+structure above C0 and C1.
+
+On the unified hierarchy, let's say U0 wants to write the pid of a
+process which has a matching uid and is currently in C10 into
+"C00/cgroup.procs". U0 obviously has write access to the file and
+migration permission on the process; however, the common ancestor of
+the source cgroup C10 and the destination cgroup C00 is above the
+points of delegation and U0 would not have write access to its
+"cgroup.procs" and thus be denied with -EACCES.
+
+
+5. Other Changes
+
+5-1. [Un]populated Notification
cgroup users often need a way to determine when a cgroup's
subhierarchy becomes empty so that it can be cleaned up. cgroup
"notify_on_release" do not exist.
-4-2. Other Core Changes
+5-2. Other Core Changes
- None of the mount options is allowed.
- The "cgroup.clone_children" file is removed.
-4-3. Per-Controller Changes
+5-3. Per-Controller Changes
-4-3-1. blkio
+5-3-1. blkio
- blk-throttle becomes properly hierarchical.
-4-3-2. cpuset
+5-3-2. cpuset
- Tasks are kept in empty cpusets after hotplug and take on the masks
of the nearest non-empty ancestor, instead of being moved to it.
masks of the nearest non-empty ancestor.
-4-3-3. memory
+5-3-3. memory
- use_hierarchy is on by default and the cgroup file for the flag is
not created.
memory.low, memory.high, and memory.max will use the string "max" to
indicate and set the highest possible value.
-5. Planned Changes
+6. Planned Changes
-5-1. CAP for resource control
+6-1. CAP for resource control
Unified hierarchy will require one of the capabilities(7), which is
yet to be decided, for all resource control related knobs. Process
CONTROL GROUP (CGROUP)
M: Tejun Heo <tj@kernel.org>
M: Li Zefan <lizefan@huawei.com>
+M: Johannes Weiner <hannes@cmpxchg.org>
L: cgroups@vger.kernel.org
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git
S: Maintained
/*
* inode.c
*/
-struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
void kernfs_evict_inode(struct inode *inode);
int kernfs_iop_permission(struct inode *inode, int mask);
int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr);
--- /dev/null
+/*
+ * linux/cgroup-defs.h - basic definitions for cgroup
+ *
+ * This file provides basic type and interface. Include this file directly
+ * only if necessary to avoid cyclic dependencies.
+ */
+#ifndef _LINUX_CGROUP_DEFS_H
+#define _LINUX_CGROUP_DEFS_H
+
+#include <linux/limits.h>
+#include <linux/list.h>
+#include <linux/idr.h>
+#include <linux/wait.h>
+#include <linux/mutex.h>
+#include <linux/rcupdate.h>
+#include <linux/percpu-refcount.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/workqueue.h>
+
+#ifdef CONFIG_CGROUPS
+
+struct cgroup;
+struct cgroup_root;
+struct cgroup_subsys;
+struct cgroup_taskset;
+struct kernfs_node;
+struct kernfs_ops;
+struct kernfs_open_file;
+struct seq_file;
+
+#define MAX_CGROUP_TYPE_NAMELEN 32
+#define MAX_CGROUP_ROOT_NAMELEN 64
+#define MAX_CFTYPE_NAME 64
+
+/* define the enumeration of all cgroup subsystems */
+#define SUBSYS(_x) _x ## _cgrp_id,
+enum cgroup_subsys_id {
+#include <linux/cgroup_subsys.h>
+ CGROUP_SUBSYS_COUNT,
+};
+#undef SUBSYS
+
+/* bits in struct cgroup_subsys_state flags field */
+enum {
+ CSS_NO_REF = (1 << 0), /* no reference counting for this css */
+ CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
+ CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
+};
+
+/* bits in struct cgroup flags field */
+enum {
+ /* Control Group requires release notifications to userspace */
+ CGRP_NOTIFY_ON_RELEASE,
+ /*
+ * Clone the parent's configuration when creating a new child
+ * cpuset cgroup. For historical reasons, this option can be
+ * specified at mount time and thus is implemented here.
+ */
+ CGRP_CPUSET_CLONE_CHILDREN,
+};
+
+/* cgroup_root->flags */
+enum {
+ CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
+ CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
+ CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
+};
+
+/* cftype->flags */
+enum {
+ CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
+ CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
+ CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
+
+ /* internal flags, do not use outside cgroup core proper */
+ __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
+ __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
+};
+
+/*
+ * Per-subsystem/per-cgroup state maintained by the system. This is the
+ * fundamental structural building block that controllers deal with.
+ *
+ * Fields marked with "PI:" are public and immutable and may be accessed
+ * directly without synchronization.
+ */
+struct cgroup_subsys_state {
+ /* PI: the cgroup that this css is attached to */
+ struct cgroup *cgroup;
+
+ /* PI: the cgroup subsystem that this css is attached to */
+ struct cgroup_subsys *ss;
+
+ /* reference count - access via css_[try]get() and css_put() */
+ struct percpu_ref refcnt;
+
+ /* PI: the parent css */
+ struct cgroup_subsys_state *parent;
+
+ /* siblings list anchored at the parent's ->children */
+ struct list_head sibling;
+ struct list_head children;
+
+ /*
+ * PI: Subsys-unique ID. 0 is unused and root is always 1. The
+ * matching css can be looked up using css_from_id().
+ */
+ int id;
+
+ unsigned int flags;
+
+ /*
+ * Monotonically increasing unique serial number which defines a
+ * uniform order among all csses. It's guaranteed that all
+ * ->children lists are in the ascending order of ->serial_nr and
+ * used to allow interrupting and resuming iterations.
+ */
+ u64 serial_nr;
+
+ /* percpu_ref killing and RCU release */
+ struct rcu_head rcu_head;
+ struct work_struct destroy_work;
+};
+
+/*
+ * A css_set is a structure holding pointers to a set of
+ * cgroup_subsys_state objects. This saves space in the task struct
+ * object and speeds up fork()/exit(), since a single inc/dec and a
+ * list_add()/del() can bump the reference count on the entire cgroup
+ * set for a task.
+ */
+struct css_set {
+ /* Reference count */
+ atomic_t refcount;
+
+ /*
+ * List running through all cgroup groups in the same hash
+ * slot. Protected by css_set_lock
+ */
+ struct hlist_node hlist;
+
+ /*
+ * Lists running through all tasks using this cgroup group.
+ * mg_tasks lists tasks which belong to this cset but are in the
+ * process of being migrated out or in. Protected by
+ * css_set_rwsem, but, during migration, once tasks are moved to
+ * mg_tasks, it can be read safely while holding cgroup_mutex.
+ */
+ struct list_head tasks;
+ struct list_head mg_tasks;
+
+ /*
+ * List of cgrp_cset_links pointing at cgroups referenced from this
+ * css_set. Protected by css_set_lock.
+ */
+ struct list_head cgrp_links;
+
+ /* the default cgroup associated with this css_set */
+ struct cgroup *dfl_cgrp;
+
+ /*
+ * Set of subsystem states, one for each subsystem. This array is
+ * immutable after creation apart from the init_css_set during
+ * subsystem registration (at boot time).
+ */
+ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+ /*
+ * List of csets participating in the on-going migration either as
+ * source or destination. Protected by cgroup_mutex.
+ */
+ struct list_head mg_preload_node;
+ struct list_head mg_node;
+
+ /*
+ * If this cset is acting as the source of migration the following
+ * two fields are set. mg_src_cgrp is the source cgroup of the
+ * on-going migration and mg_dst_cset is the destination cset the
+ * target tasks on this cset should be migrated to. Protected by
+ * cgroup_mutex.
+ */
+ struct cgroup *mg_src_cgrp;
+ struct css_set *mg_dst_cset;
+
+ /*
+ * On the default hierarhcy, ->subsys[ssid] may point to a css
+ * attached to an ancestor instead of the cgroup this css_set is
+ * associated with. The following node is anchored at
+ * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
+ * iterate through all css's attached to a given cgroup.
+ */
+ struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
+
+ /* For RCU-protected deletion */
+ struct rcu_head rcu_head;
+};
+
+struct cgroup {
+ /* self css with NULL ->ss, points back to this cgroup */
+ struct cgroup_subsys_state self;
+
+ unsigned long flags; /* "unsigned long" so bitops work */
+
+ /*
+ * idr allocated in-hierarchy ID.
+ *
+ * ID 0 is not used, the ID of the root cgroup is always 1, and a
+ * new cgroup will be assigned with a smallest available ID.
+ *
+ * Allocating/Removing ID must be protected by cgroup_mutex.
+ */
+ int id;
+
+ /*
+ * If this cgroup contains any tasks, it contributes one to
+ * populated_cnt. All children with non-zero popuplated_cnt of
+ * their own contribute one. The count is zero iff there's no task
+ * in this cgroup or its subtree.
+ */
+ int populated_cnt;
+
+ struct kernfs_node *kn; /* cgroup kernfs entry */
+ struct kernfs_node *procs_kn; /* kn for "cgroup.procs" */
+ struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
+
+ /*
+ * The bitmask of subsystems enabled on the child cgroups.
+ * ->subtree_control is the one configured through
+ * "cgroup.subtree_control" while ->child_subsys_mask is the
+ * effective one which may have more subsystems enabled.
+ * Controller knobs are made available iff it's enabled in
+ * ->subtree_control.
+ */
+ unsigned int subtree_control;
+ unsigned int child_subsys_mask;
+
+ /* Private pointers for each registered subsystem */
+ struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
+
+ struct cgroup_root *root;
+
+ /*
+ * List of cgrp_cset_links pointing at css_sets with tasks in this
+ * cgroup. Protected by css_set_lock.
+ */
+ struct list_head cset_links;
+
+ /*
+ * On the default hierarchy, a css_set for a cgroup with some
+ * susbsys disabled will point to css's which are associated with
+ * the closest ancestor which has the subsys enabled. The
+ * following lists all css_sets which point to this cgroup's css
+ * for the given subsystem.
+ */
+ struct list_head e_csets[CGROUP_SUBSYS_COUNT];
+
+ /*
+ * list of pidlists, up to two for each namespace (one for procs, one
+ * for tasks); created on demand.
+ */
+ struct list_head pidlists;
+ struct mutex pidlist_mutex;
+
+ /* used to wait for offlining of csses */
+ wait_queue_head_t offline_waitq;
+
+ /* used to schedule release agent */
+ struct work_struct release_agent_work;
+};
+
+/*
+ * A cgroup_root represents the root of a cgroup hierarchy, and may be
+ * associated with a kernfs_root to form an active hierarchy. This is
+ * internal to cgroup core. Don't access directly from controllers.
+ */
+struct cgroup_root {
+ struct kernfs_root *kf_root;
+
+ /* The bitmask of subsystems attached to this hierarchy */
+ unsigned int subsys_mask;
+
+ /* Unique id for this hierarchy. */
+ int hierarchy_id;
+
+ /* The root cgroup. Root is destroyed on its release. */
+ struct cgroup cgrp;
+
+ /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
+ atomic_t nr_cgrps;
+
+ /* A list running through the active hierarchies */
+ struct list_head root_list;
+
+ /* Hierarchy-specific flags */
+ unsigned int flags;
+
+ /* IDs for cgroups in this hierarchy */
+ struct idr cgroup_idr;
+
+ /* The path to use for release notifications. */
+ char release_agent_path[PATH_MAX];
+
+ /* The name for this hierarchy - may be empty */
+ char name[MAX_CGROUP_ROOT_NAMELEN];
+};
+
+/*
+ * struct cftype: handler definitions for cgroup control files
+ *
+ * When reading/writing to a file:
+ * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
+ * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
+ */
+struct cftype {
+ /*
+ * By convention, the name should begin with the name of the
+ * subsystem, followed by a period. Zero length string indicates
+ * end of cftype array.
+ */
+ char name[MAX_CFTYPE_NAME];
+ int private;
+ /*
+ * If not 0, file mode is set to this value, otherwise it will
+ * be figured out automatically
+ */
+ umode_t mode;
+
+ /*
+ * The maximum length of string, excluding trailing nul, that can
+ * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
+ */
+ size_t max_write_len;
+
+ /* CFTYPE_* flags */
+ unsigned int flags;
+
+ /*
+ * Fields used for internal bookkeeping. Initialized automatically
+ * during registration.
+ */
+ struct cgroup_subsys *ss; /* NULL for cgroup core files */
+ struct list_head node; /* anchored at ss->cfts */
+ struct kernfs_ops *kf_ops;
+
+ /*
+ * read_u64() is a shortcut for the common case of returning a
+ * single integer. Use it in place of read()
+ */
+ u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
+ /*
+ * read_s64() is a signed version of read_u64()
+ */
+ s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
+
+ /* generic seq_file read interface */
+ int (*seq_show)(struct seq_file *sf, void *v);
+
+ /* optional ops, implement all or none */
+ void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
+ void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
+ void (*seq_stop)(struct seq_file *sf, void *v);
+
+ /*
+ * write_u64() is a shortcut for the common case of accepting
+ * a single integer (as parsed by simple_strtoull) from
+ * userspace. Use in place of write(); return 0 or error.
+ */
+ int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
+ u64 val);
+ /*
+ * write_s64() is a signed version of write_u64()
+ */
+ int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
+ s64 val);
+
+ /*
+ * write() is the generic write callback which maps directly to
+ * kernfs write operation and overrides all other operations.
+ * Maximum write size is determined by ->max_write_len. Use
+ * of_css/cft() to access the associated css and cft.
+ */
+ ssize_t (*write)(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct lock_class_key lockdep_key;
+#endif
+};
+
+/*
+ * Control Group subsystem type.
+ * See Documentation/cgroups/cgroups.txt for details
+ */
+struct cgroup_subsys {
+ struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
+ int (*css_online)(struct cgroup_subsys_state *css);
+ void (*css_offline)(struct cgroup_subsys_state *css);
+ void (*css_released)(struct cgroup_subsys_state *css);
+ void (*css_free)(struct cgroup_subsys_state *css);
+ void (*css_reset)(struct cgroup_subsys_state *css);
+ void (*css_e_css_changed)(struct cgroup_subsys_state *css);
+
+ int (*can_attach)(struct cgroup_subsys_state *css,
+ struct cgroup_taskset *tset);
+ void (*cancel_attach)(struct cgroup_subsys_state *css,
+ struct cgroup_taskset *tset);
+ void (*attach)(struct cgroup_subsys_state *css,
+ struct cgroup_taskset *tset);
+ void (*fork)(struct task_struct *task);
+ void (*exit)(struct cgroup_subsys_state *css,
+ struct cgroup_subsys_state *old_css,
+ struct task_struct *task);
+ void (*bind)(struct cgroup_subsys_state *root_css);
+
+ int disabled;
+ int early_init;
+
+ /*
+ * If %false, this subsystem is properly hierarchical -
+ * configuration, resource accounting and restriction on a parent
+ * cgroup cover those of its children. If %true, hierarchy support
+ * is broken in some ways - some subsystems ignore hierarchy
+ * completely while others are only implemented half-way.
+ *
+ * It's now disallowed to create nested cgroups if the subsystem is
+ * broken and cgroup core will emit a warning message on such
+ * cases. Eventually, all subsystems will be made properly
+ * hierarchical and this will go away.
+ */
+ bool broken_hierarchy;
+ bool warned_broken_hierarchy;
+
+ /* the following two fields are initialized automtically during boot */
+ int id;
+ const char *name;
+
+ /* link to parent, protected by cgroup_lock() */
+ struct cgroup_root *root;
+
+ /* idr for css->id */
+ struct idr css_idr;
+
+ /*
+ * List of cftypes. Each entry is the first entry of an array
+ * terminated by zero length name.
+ */
+ struct list_head cfts;
+
+ /*
+ * Base cftypes which are automatically registered. The two can
+ * point to the same array.
+ */
+ struct cftype *dfl_cftypes; /* for the default hierarchy */
+ struct cftype *legacy_cftypes; /* for the legacy hierarchies */
+
+ /*
+ * A subsystem may depend on other subsystems. When such subsystem
+ * is enabled on a cgroup, the depended-upon subsystems are enabled
+ * together if available. Subsystems enabled due to dependency are
+ * not visible to userland until explicitly enabled. The following
+ * specifies the mask of subsystems that this one depends on.
+ */
+ unsigned int depends_on;
+};
+
+extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
+
+/**
+ * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
+ * @tsk: target task
+ *
+ * Called from threadgroup_change_begin() and allows cgroup operations to
+ * synchronize against threadgroup changes using a percpu_rw_semaphore.
+ */
+static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
+{
+ percpu_down_read(&cgroup_threadgroup_rwsem);
+}
+
+/**
+ * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
+ * @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 */
+
+#define CGROUP_SUBSYS_COUNT 0
+
+static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
+static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}
+
+#endif /* CONFIG_CGROUPS */
+
+#endif /* _LINUX_CGROUP_DEFS_H */
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/nodemask.h>
-#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/cgroupstats.h>
#include <linux/rwsem.h>
-#include <linux/idr.h>
-#include <linux/workqueue.h>
#include <linux/fs.h>
-#include <linux/percpu-refcount.h>
#include <linux/seq_file.h>
#include <linux/kernfs.h>
-#include <linux/wait.h>
+
+#include <linux/cgroup-defs.h>
#ifdef CONFIG_CGROUPS
-struct cgroup_root;
-struct cgroup_subsys;
-struct cgroup;
+/* a css_task_iter should be treated as an opaque object */
+struct css_task_iter {
+ struct cgroup_subsys *ss;
+
+ struct list_head *cset_pos;
+ struct list_head *cset_head;
-extern int cgroup_init_early(void);
-extern int cgroup_init(void);
-extern void cgroup_fork(struct task_struct *p);
-extern void cgroup_post_fork(struct task_struct *p);
-extern void cgroup_exit(struct task_struct *p);
-extern int cgroupstats_build(struct cgroupstats *stats,
- struct dentry *dentry);
+ struct list_head *task_pos;
+ struct list_head *tasks_head;
+ struct list_head *mg_tasks_head;
+};
-extern int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk);
+extern struct cgroup_root cgrp_dfl_root;
+extern struct css_set init_css_set;
-/* define the enumeration of all cgroup subsystems */
-#define SUBSYS(_x) _x ## _cgrp_id,
-enum cgroup_subsys_id {
+#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
#include <linux/cgroup_subsys.h>
- CGROUP_SUBSYS_COUNT,
-};
#undef SUBSYS
+bool css_has_online_children(struct cgroup_subsys_state *css);
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
+ struct cgroup_subsys *ss);
+struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss);
+
+bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
+
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
+int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
+int cgroup_rm_cftypes(struct cftype *cfts);
+
+char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
+int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk);
+
+void cgroup_fork(struct task_struct *p);
+void cgroup_post_fork(struct task_struct *p);
+void cgroup_exit(struct task_struct *p);
+
+int cgroup_init_early(void);
+int cgroup_init(void);
+
/*
- * Per-subsystem/per-cgroup state maintained by the system. This is the
- * fundamental structural building block that controllers deal with.
+ * Iteration helpers and macros.
+ */
+
+struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *parent);
+struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *css);
+struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos);
+struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *css);
+
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
+
+void css_task_iter_start(struct cgroup_subsys_state *css,
+ struct css_task_iter *it);
+struct task_struct *css_task_iter_next(struct css_task_iter *it);
+void css_task_iter_end(struct css_task_iter *it);
+
+/**
+ * css_for_each_child - iterate through children of a css
+ * @pos: the css * to use as the loop cursor
+ * @parent: css whose children to walk
+ *
+ * Walk @parent's children. Must be called under rcu_read_lock().
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
*
- * Fields marked with "PI:" are public and immutable and may be accessed
- * directly without synchronization.
+ * It is allowed to temporarily drop RCU read lock during iteration. The
+ * caller is responsible for ensuring that @pos remains accessible until
+ * the start of the next iteration by, for example, bumping the css refcnt.
*/
-struct cgroup_subsys_state {
- /* PI: the cgroup that this css is attached to */
- struct cgroup *cgroup;
-
- /* PI: the cgroup subsystem that this css is attached to */
- struct cgroup_subsys *ss;
-
- /* reference count - access via css_[try]get() and css_put() */
- struct percpu_ref refcnt;
-
- /* PI: the parent css */
- struct cgroup_subsys_state *parent;
-
- /* siblings list anchored at the parent's ->children */
- struct list_head sibling;
- struct list_head children;
-
- /*
- * PI: Subsys-unique ID. 0 is unused and root is always 1. The
- * matching css can be looked up using css_from_id().
- */
- int id;
-
- unsigned int flags;
-
- /*
- * Monotonically increasing unique serial number which defines a
- * uniform order among all csses. It's guaranteed that all
- * ->children lists are in the ascending order of ->serial_nr and
- * used to allow interrupting and resuming iterations.
- */
- u64 serial_nr;
-
- /* percpu_ref killing and RCU release */
- struct rcu_head rcu_head;
- struct work_struct destroy_work;
-};
+#define css_for_each_child(pos, parent) \
+ for ((pos) = css_next_child(NULL, (parent)); (pos); \
+ (pos) = css_next_child((pos), (parent)))
-/* bits in struct cgroup_subsys_state flags field */
-enum {
- CSS_NO_REF = (1 << 0), /* no reference counting for this css */
- CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
- CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
-};
+/**
+ * css_for_each_descendant_pre - pre-order walk of a css's descendants
+ * @pos: the css * to use as the loop cursor
+ * @root: css whose descendants to walk
+ *
+ * Walk @root's descendants. @root is included in the iteration and the
+ * first node to be visited. Must be called under rcu_read_lock().
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ *
+ * For example, the following guarantees that a descendant can't escape
+ * state updates of its ancestors.
+ *
+ * my_online(@css)
+ * {
+ * Lock @css's parent and @css;
+ * Inherit state from the parent;
+ * Unlock both.
+ * }
+ *
+ * my_update_state(@css)
+ * {
+ * css_for_each_descendant_pre(@pos, @css) {
+ * Lock @pos;
+ * if (@pos == @css)
+ * Update @css's state;
+ * else
+ * Verify @pos is alive and inherit state from its parent;
+ * Unlock @pos;
+ * }
+ * }
+ *
+ * As long as the inheriting step, including checking the parent state, is
+ * enclosed inside @pos locking, double-locking the parent isn't necessary
+ * while inheriting. The state update to the parent is guaranteed to be
+ * visible by walking order and, as long as inheriting operations to the
+ * same @pos are atomic to each other, multiple updates racing each other
+ * still result in the correct state. It's guaranateed that at least one
+ * inheritance happens for any css after the latest update to its parent.
+ *
+ * If checking parent's state requires locking the parent, each inheriting
+ * iteration should lock and unlock both @pos->parent and @pos.
+ *
+ * Alternatively, a subsystem may choose to use a single global lock to
+ * synchronize ->css_online() and ->css_offline() against tree-walking
+ * operations.
+ *
+ * It is allowed to temporarily drop RCU read lock during iteration. The
+ * caller is responsible for ensuring that @pos remains accessible until
+ * the start of the next iteration by, for example, bumping the css refcnt.
+ */
+#define css_for_each_descendant_pre(pos, css) \
+ for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
+ (pos) = css_next_descendant_pre((pos), (css)))
+
+/**
+ * css_for_each_descendant_post - post-order walk of a css's descendants
+ * @pos: the css * to use as the loop cursor
+ * @css: css whose descendants to walk
+ *
+ * Similar to css_for_each_descendant_pre() but performs post-order
+ * traversal instead. @root is included in the iteration and the last
+ * node to be visited.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ *
+ * Note that the walk visibility guarantee example described in pre-order
+ * walk doesn't apply the same to post-order walks.
+ */
+#define css_for_each_descendant_post(pos, css) \
+ for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
+ (pos) = css_next_descendant_post((pos), (css)))
+
+/**
+ * cgroup_taskset_for_each - iterate cgroup_taskset
+ * @task: the loop cursor
+ * @tset: taskset to iterate
+ */
+#define cgroup_taskset_for_each(task, tset) \
+ for ((task) = cgroup_taskset_first((tset)); (task); \
+ (task) = cgroup_taskset_next((tset)))
+
+/*
+ * Inline functions.
+ */
/**
* css_get - obtain a reference on the specified css
{
if (!(css->flags & CSS_NO_REF))
return percpu_ref_tryget_live(&css->refcnt);
- return true;
-}
-
-/**
- * css_put - put a css reference
- * @css: target css
- *
- * Put a reference obtained via css_get() and css_tryget_online().
- */
-static inline void css_put(struct cgroup_subsys_state *css)
-{
- if (!(css->flags & CSS_NO_REF))
- percpu_ref_put(&css->refcnt);
-}
-
-/**
- * css_put_many - put css references
- * @css: target css
- * @n: number of references to put
- *
- * Put references obtained via css_get() and css_tryget_online().
- */
-static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
-{
- if (!(css->flags & CSS_NO_REF))
- percpu_ref_put_many(&css->refcnt, n);
-}
-
-/* bits in struct cgroup flags field */
-enum {
- /* Control Group requires release notifications to userspace */
- CGRP_NOTIFY_ON_RELEASE,
- /*
- * Clone the parent's configuration when creating a new child
- * cpuset cgroup. For historical reasons, this option can be
- * specified at mount time and thus is implemented here.
- */
- CGRP_CPUSET_CLONE_CHILDREN,
-};
-
-struct cgroup {
- /* self css with NULL ->ss, points back to this cgroup */
- struct cgroup_subsys_state self;
-
- unsigned long flags; /* "unsigned long" so bitops work */
-
- /*
- * idr allocated in-hierarchy ID.
- *
- * ID 0 is not used, the ID of the root cgroup is always 1, and a
- * new cgroup will be assigned with a smallest available ID.
- *
- * Allocating/Removing ID must be protected by cgroup_mutex.
- */
- int id;
-
- /*
- * If this cgroup contains any tasks, it contributes one to
- * populated_cnt. All children with non-zero popuplated_cnt of
- * their own contribute one. The count is zero iff there's no task
- * in this cgroup or its subtree.
- */
- int populated_cnt;
-
- struct kernfs_node *kn; /* cgroup kernfs entry */
- struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
-
- /*
- * The bitmask of subsystems enabled on the child cgroups.
- * ->subtree_control is the one configured through
- * "cgroup.subtree_control" while ->child_subsys_mask is the
- * effective one which may have more subsystems enabled.
- * Controller knobs are made available iff it's enabled in
- * ->subtree_control.
- */
- unsigned int subtree_control;
- unsigned int child_subsys_mask;
-
- /* Private pointers for each registered subsystem */
- struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
-
- struct cgroup_root *root;
-
- /*
- * List of cgrp_cset_links pointing at css_sets with tasks in this
- * cgroup. Protected by css_set_lock.
- */
- struct list_head cset_links;
-
- /*
- * On the default hierarchy, a css_set for a cgroup with some
- * susbsys disabled will point to css's which are associated with
- * the closest ancestor which has the subsys enabled. The
- * following lists all css_sets which point to this cgroup's css
- * for the given subsystem.
- */
- struct list_head e_csets[CGROUP_SUBSYS_COUNT];
-
- /*
- * list of pidlists, up to two for each namespace (one for procs, one
- * for tasks); created on demand.
- */
- struct list_head pidlists;
- struct mutex pidlist_mutex;
-
- /* used to wait for offlining of csses */
- wait_queue_head_t offline_waitq;
-
- /* used to schedule release agent */
- struct work_struct release_agent_work;
-};
-
-#define MAX_CGROUP_ROOT_NAMELEN 64
-
-/* cgroup_root->flags */
-enum {
- CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
- CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
- CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
-};
-
-/*
- * A cgroup_root represents the root of a cgroup hierarchy, and may be
- * associated with a kernfs_root to form an active hierarchy. This is
- * internal to cgroup core. Don't access directly from controllers.
- */
-struct cgroup_root {
- struct kernfs_root *kf_root;
-
- /* The bitmask of subsystems attached to this hierarchy */
- unsigned int subsys_mask;
-
- /* Unique id for this hierarchy. */
- int hierarchy_id;
-
- /* The root cgroup. Root is destroyed on its release. */
- struct cgroup cgrp;
-
- /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
- atomic_t nr_cgrps;
-
- /* A list running through the active hierarchies */
- struct list_head root_list;
-
- /* Hierarchy-specific flags */
- unsigned int flags;
-
- /* IDs for cgroups in this hierarchy */
- struct idr cgroup_idr;
-
- /* The path to use for release notifications. */
- char release_agent_path[PATH_MAX];
-
- /* The name for this hierarchy - may be empty */
- char name[MAX_CGROUP_ROOT_NAMELEN];
-};
-
-/*
- * A css_set is a structure holding pointers to a set of
- * cgroup_subsys_state objects. This saves space in the task struct
- * object and speeds up fork()/exit(), since a single inc/dec and a
- * list_add()/del() can bump the reference count on the entire cgroup
- * set for a task.
- */
-
-struct css_set {
-
- /* Reference count */
- atomic_t refcount;
-
- /*
- * List running through all cgroup groups in the same hash
- * slot. Protected by css_set_lock
- */
- struct hlist_node hlist;
-
- /*
- * Lists running through all tasks using this cgroup group.
- * mg_tasks lists tasks which belong to this cset but are in the
- * process of being migrated out or in. Protected by
- * css_set_rwsem, but, during migration, once tasks are moved to
- * mg_tasks, it can be read safely while holding cgroup_mutex.
- */
- struct list_head tasks;
- struct list_head mg_tasks;
-
- /*
- * List of cgrp_cset_links pointing at cgroups referenced from this
- * css_set. Protected by css_set_lock.
- */
- struct list_head cgrp_links;
-
- /* the default cgroup associated with this css_set */
- struct cgroup *dfl_cgrp;
-
- /*
- * Set of subsystem states, one for each subsystem. This array is
- * immutable after creation apart from the init_css_set during
- * subsystem registration (at boot time).
- */
- struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
-
- /*
- * List of csets participating in the on-going migration either as
- * source or destination. Protected by cgroup_mutex.
- */
- struct list_head mg_preload_node;
- struct list_head mg_node;
-
- /*
- * If this cset is acting as the source of migration the following
- * two fields are set. mg_src_cgrp is the source cgroup of the
- * on-going migration and mg_dst_cset is the destination cset the
- * target tasks on this cset should be migrated to. Protected by
- * cgroup_mutex.
- */
- struct cgroup *mg_src_cgrp;
- struct css_set *mg_dst_cset;
-
- /*
- * On the default hierarhcy, ->subsys[ssid] may point to a css
- * attached to an ancestor instead of the cgroup this css_set is
- * associated with. The following node is anchored at
- * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
- * iterate through all css's attached to a given cgroup.
- */
- struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
-
- /* For RCU-protected deletion */
- struct rcu_head rcu_head;
-};
-
-/*
- * struct cftype: handler definitions for cgroup control files
- *
- * When reading/writing to a file:
- * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
- * - the 'cftype' of the file is file->f_path.dentry->d_fsdata
- */
-
-/* cftype->flags */
-enum {
- CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */
- CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */
- CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
-
- /* internal flags, do not use outside cgroup core proper */
- __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
- __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
-};
-
-#define MAX_CFTYPE_NAME 64
-
-struct cftype {
- /*
- * By convention, the name should begin with the name of the
- * subsystem, followed by a period. Zero length string indicates
- * end of cftype array.
- */
- char name[MAX_CFTYPE_NAME];
- int private;
- /*
- * If not 0, file mode is set to this value, otherwise it will
- * be figured out automatically
- */
- umode_t mode;
-
- /*
- * The maximum length of string, excluding trailing nul, that can
- * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
- */
- size_t max_write_len;
-
- /* CFTYPE_* flags */
- unsigned int flags;
-
- /*
- * Fields used for internal bookkeeping. Initialized automatically
- * during registration.
- */
- struct cgroup_subsys *ss; /* NULL for cgroup core files */
- struct list_head node; /* anchored at ss->cfts */
- struct kernfs_ops *kf_ops;
-
- /*
- * read_u64() is a shortcut for the common case of returning a
- * single integer. Use it in place of read()
- */
- u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);
- /*
- * read_s64() is a signed version of read_u64()
- */
- s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);
-
- /* generic seq_file read interface */
- int (*seq_show)(struct seq_file *sf, void *v);
-
- /* optional ops, implement all or none */
- void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
- void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
- void (*seq_stop)(struct seq_file *sf, void *v);
-
- /*
- * write_u64() is a shortcut for the common case of accepting
- * a single integer (as parsed by simple_strtoull) from
- * userspace. Use in place of write(); return 0 or error.
- */
- int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft,
- u64 val);
- /*
- * write_s64() is a signed version of write_u64()
- */
- int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
- s64 val);
-
- /*
- * write() is the generic write callback which maps directly to
- * kernfs write operation and overrides all other operations.
- * Maximum write size is determined by ->max_write_len. Use
- * of_css/cft() to access the associated css and cft.
- */
- ssize_t (*write)(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off);
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lock_class_key lockdep_key;
-#endif
-};
-
-extern struct cgroup_root cgrp_dfl_root;
-extern struct css_set init_css_set;
-
-/**
- * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
- * @cgrp: the cgroup of interest
- *
- * The default hierarchy is the v2 interface of cgroup and this function
- * can be used to test whether a cgroup is on the default hierarchy for
- * cases where a subsystem should behave differnetly depending on the
- * interface version.
- *
- * The set of behaviors which change on the default hierarchy are still
- * being determined and the mount option is prefixed with __DEVEL__.
- *
- * List of changed behaviors:
- *
- * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
- * and "name" are disallowed.
- *
- * - When mounting an existing superblock, mount options should match.
- *
- * - Remount is disallowed.
- *
- * - rename(2) is disallowed.
- *
- * - "tasks" is removed. Everything should be at process granularity. Use
- * "cgroup.procs" instead.
- *
- * - "cgroup.procs" is not sorted. pids will be unique unless they got
- * recycled inbetween reads.
- *
- * - "release_agent" and "notify_on_release" are removed. Replacement
- * notification mechanism will be implemented.
- *
- * - "cgroup.clone_children" is removed.
- *
- * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
- * and its descendants contain no task; otherwise, 1. The file also
- * generates kernfs notification which can be monitored through poll and
- * [di]notify when the value of the file changes.
- *
- * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
- * take masks of ancestors with non-empty cpus/mems, instead of being
- * moved to an ancestor.
- *
- * - cpuset: a task can be moved into an empty cpuset, and again it takes
- * masks of ancestors.
- *
- * - memcg: use_hierarchy is on by default and the cgroup file for the flag
- * is not created.
- *
- * - blkcg: blk-throttle becomes properly hierarchical.
- *
- * - debug: disallowed on the default hierarchy.
- */
-static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
-{
- return cgrp->root == &cgrp_dfl_root;
-}
-
-/* no synchronization, the result can only be used as a hint */
-static inline bool cgroup_has_tasks(struct cgroup *cgrp)
-{
- return !list_empty(&cgrp->cset_links);
-}
-
-/* returns ino associated with a cgroup */
-static inline ino_t cgroup_ino(struct cgroup *cgrp)
-{
- return cgrp->kn->ino;
-}
-
-/* cft/css accessors for cftype->write() operation */
-static inline struct cftype *of_cft(struct kernfs_open_file *of)
-{
- return of->kn->priv;
-}
-
-struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
-
-/* cft/css accessors for cftype->seq_*() operations */
-static inline struct cftype *seq_cft(struct seq_file *seq)
-{
- return of_cft(seq->private);
-}
-
-static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
-{
- return of_css(seq->private);
-}
-
-/*
- * Name / path handling functions. All are thin wrappers around the kernfs
- * counterparts and can be called under any context.
- */
-
-static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
-{
- return kernfs_name(cgrp->kn, buf, buflen);
-}
-
-static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
- size_t buflen)
-{
- return kernfs_path(cgrp->kn, buf, buflen);
-}
-
-static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
-{
- pr_cont_kernfs_name(cgrp->kn);
-}
-
-static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
-{
- pr_cont_kernfs_path(cgrp->kn);
-}
-
-char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
-
-int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
-int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
-int cgroup_rm_cftypes(struct cftype *cfts);
-
-bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
-
-/*
- * Control Group taskset, used to pass around set of tasks to cgroup_subsys
- * methods.
- */
-struct cgroup_taskset;
-struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
-struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
+ return true;
+}
/**
- * cgroup_taskset_for_each - iterate cgroup_taskset
- * @task: the loop cursor
- * @tset: taskset to iterate
+ * css_put - put a css reference
+ * @css: target css
+ *
+ * Put a reference obtained via css_get() and css_tryget_online().
*/
-#define cgroup_taskset_for_each(task, tset) \
- for ((task) = cgroup_taskset_first((tset)); (task); \
- (task) = cgroup_taskset_next((tset)))
+static inline void css_put(struct cgroup_subsys_state *css)
+{
+ if (!(css->flags & CSS_NO_REF))
+ percpu_ref_put(&css->refcnt);
+}
-/*
- * Control Group subsystem type.
- * See Documentation/cgroups/cgroups.txt for details
+/**
+ * css_put_many - put css references
+ * @css: target css
+ * @n: number of references to put
+ *
+ * Put references obtained via css_get() and css_tryget_online().
*/
-
-struct cgroup_subsys {
- struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
- int (*css_online)(struct cgroup_subsys_state *css);
- void (*css_offline)(struct cgroup_subsys_state *css);
- void (*css_released)(struct cgroup_subsys_state *css);
- void (*css_free)(struct cgroup_subsys_state *css);
- void (*css_reset)(struct cgroup_subsys_state *css);
- void (*css_e_css_changed)(struct cgroup_subsys_state *css);
-
- int (*can_attach)(struct cgroup_subsys_state *css,
- struct cgroup_taskset *tset);
- void (*cancel_attach)(struct cgroup_subsys_state *css,
- struct cgroup_taskset *tset);
- void (*attach)(struct cgroup_subsys_state *css,
- struct cgroup_taskset *tset);
- void (*fork)(struct task_struct *task);
- void (*exit)(struct cgroup_subsys_state *css,
- struct cgroup_subsys_state *old_css,
- struct task_struct *task);
- void (*bind)(struct cgroup_subsys_state *root_css);
-
- int disabled;
- int early_init;
-
- /*
- * If %false, this subsystem is properly hierarchical -
- * configuration, resource accounting and restriction on a parent
- * cgroup cover those of its children. If %true, hierarchy support
- * is broken in some ways - some subsystems ignore hierarchy
- * completely while others are only implemented half-way.
- *
- * It's now disallowed to create nested cgroups if the subsystem is
- * broken and cgroup core will emit a warning message on such
- * cases. Eventually, all subsystems will be made properly
- * hierarchical and this will go away.
- */
- bool broken_hierarchy;
- bool warned_broken_hierarchy;
-
- /* the following two fields are initialized automtically during boot */
- int id;
-#define MAX_CGROUP_TYPE_NAMELEN 32
- const char *name;
-
- /* link to parent, protected by cgroup_lock() */
- struct cgroup_root *root;
-
- /* idr for css->id */
- struct idr css_idr;
-
- /*
- * List of cftypes. Each entry is the first entry of an array
- * terminated by zero length name.
- */
- struct list_head cfts;
-
- /*
- * Base cftypes which are automatically registered. The two can
- * point to the same array.
- */
- struct cftype *dfl_cftypes; /* for the default hierarchy */
- struct cftype *legacy_cftypes; /* for the legacy hierarchies */
-
- /*
- * A subsystem may depend on other subsystems. When such subsystem
- * is enabled on a cgroup, the depended-upon subsystems are enabled
- * together if available. Subsystems enabled due to dependency are
- * not visible to userland until explicitly enabled. The following
- * specifies the mask of subsystems that this one depends on.
- */
- unsigned int depends_on;
-};
-
-#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
-#include <linux/cgroup_subsys.h>
-#undef SUBSYS
+static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
+{
+ if (!(css->flags & CSS_NO_REF))
+ percpu_ref_put_many(&css->refcnt, n);
+}
/**
* task_css_set_check - obtain a task's css_set with extra access conditions
return task_css(task, subsys_id)->cgroup;
}
-struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *parent);
-
-struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
-
/**
- * css_for_each_child - iterate through children of a css
- * @pos: the css * to use as the loop cursor
- * @parent: css whose children to walk
+ * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
+ * @cgrp: the cgroup of interest
*
- * Walk @parent's children. Must be called under rcu_read_lock().
+ * The default hierarchy is the v2 interface of cgroup and this function
+ * can be used to test whether a cgroup is on the default hierarchy for
+ * cases where a subsystem should behave differnetly depending on the
+ * interface version.
*
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
+ * The set of behaviors which change on the default hierarchy are still
+ * being determined and the mount option is prefixed with __DEVEL__.
*
- * It is allowed to temporarily drop RCU read lock during iteration. The
- * caller is responsible for ensuring that @pos remains accessible until
- * the start of the next iteration by, for example, bumping the css refcnt.
- */
-#define css_for_each_child(pos, parent) \
- for ((pos) = css_next_child(NULL, (parent)); (pos); \
- (pos) = css_next_child((pos), (parent)))
-
-struct cgroup_subsys_state *
-css_next_descendant_pre(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *css);
-
-struct cgroup_subsys_state *
-css_rightmost_descendant(struct cgroup_subsys_state *pos);
-
-/**
- * css_for_each_descendant_pre - pre-order walk of a css's descendants
- * @pos: the css * to use as the loop cursor
- * @root: css whose descendants to walk
+ * List of changed behaviors:
*
- * Walk @root's descendants. @root is included in the iteration and the
- * first node to be visited. Must be called under rcu_read_lock().
+ * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
+ * and "name" are disallowed.
*
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
+ * - When mounting an existing superblock, mount options should match.
*
- * For example, the following guarantees that a descendant can't escape
- * state updates of its ancestors.
+ * - Remount is disallowed.
*
- * my_online(@css)
- * {
- * Lock @css's parent and @css;
- * Inherit state from the parent;
- * Unlock both.
- * }
+ * - rename(2) is disallowed.
*
- * my_update_state(@css)
- * {
- * css_for_each_descendant_pre(@pos, @css) {
- * Lock @pos;
- * if (@pos == @css)
- * Update @css's state;
- * else
- * Verify @pos is alive and inherit state from its parent;
- * Unlock @pos;
- * }
- * }
+ * - "tasks" is removed. Everything should be at process granularity. Use
+ * "cgroup.procs" instead.
*
- * As long as the inheriting step, including checking the parent state, is
- * enclosed inside @pos locking, double-locking the parent isn't necessary
- * while inheriting. The state update to the parent is guaranteed to be
- * visible by walking order and, as long as inheriting operations to the
- * same @pos are atomic to each other, multiple updates racing each other
- * still result in the correct state. It's guaranateed that at least one
- * inheritance happens for any css after the latest update to its parent.
+ * - "cgroup.procs" is not sorted. pids will be unique unless they got
+ * recycled inbetween reads.
*
- * If checking parent's state requires locking the parent, each inheriting
- * iteration should lock and unlock both @pos->parent and @pos.
+ * - "release_agent" and "notify_on_release" are removed. Replacement
+ * notification mechanism will be implemented.
*
- * Alternatively, a subsystem may choose to use a single global lock to
- * synchronize ->css_online() and ->css_offline() against tree-walking
- * operations.
+ * - "cgroup.clone_children" is removed.
*
- * It is allowed to temporarily drop RCU read lock during iteration. The
- * caller is responsible for ensuring that @pos remains accessible until
- * the start of the next iteration by, for example, bumping the css refcnt.
- */
-#define css_for_each_descendant_pre(pos, css) \
- for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \
- (pos) = css_next_descendant_pre((pos), (css)))
-
-struct cgroup_subsys_state *
-css_next_descendant_post(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *css);
-
-/**
- * css_for_each_descendant_post - post-order walk of a css's descendants
- * @pos: the css * to use as the loop cursor
- * @css: css whose descendants to walk
+ * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
+ * and its descendants contain no task; otherwise, 1. The file also
+ * generates kernfs notification which can be monitored through poll and
+ * [di]notify when the value of the file changes.
*
- * Similar to css_for_each_descendant_pre() but performs post-order
- * traversal instead. @root is included in the iteration and the last
- * node to be visited.
+ * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
+ * take masks of ancestors with non-empty cpus/mems, instead of being
+ * moved to an ancestor.
*
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
+ * - cpuset: a task can be moved into an empty cpuset, and again it takes
+ * masks of ancestors.
*
- * Note that the walk visibility guarantee example described in pre-order
- * walk doesn't apply the same to post-order walks.
+ * - memcg: use_hierarchy is on by default and the cgroup file for the flag
+ * is not created.
+ *
+ * - blkcg: blk-throttle becomes properly hierarchical.
+ *
+ * - debug: disallowed on the default hierarchy.
*/
-#define css_for_each_descendant_post(pos, css) \
- for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
- (pos) = css_next_descendant_post((pos), (css)))
+static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
+{
+ return cgrp->root == &cgrp_dfl_root;
+}
-bool css_has_online_children(struct cgroup_subsys_state *css);
+/* no synchronization, the result can only be used as a hint */
+static inline bool cgroup_has_tasks(struct cgroup *cgrp)
+{
+ return !list_empty(&cgrp->cset_links);
+}
-/* A css_task_iter should be treated as an opaque object */
-struct css_task_iter {
- struct cgroup_subsys *ss;
+/* returns ino associated with a cgroup */
+static inline ino_t cgroup_ino(struct cgroup *cgrp)
+{
+ return cgrp->kn->ino;
+}
- struct list_head *cset_pos;
- struct list_head *cset_head;
+/* cft/css accessors for cftype->write() operation */
+static inline struct cftype *of_cft(struct kernfs_open_file *of)
+{
+ return of->kn->priv;
+}
- struct list_head *task_pos;
- struct list_head *tasks_head;
- struct list_head *mg_tasks_head;
-};
+struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
-void css_task_iter_start(struct cgroup_subsys_state *css,
- struct css_task_iter *it);
-struct task_struct *css_task_iter_next(struct css_task_iter *it);
-void css_task_iter_end(struct css_task_iter *it);
+/* cft/css accessors for cftype->seq_*() operations */
+static inline struct cftype *seq_cft(struct seq_file *seq)
+{
+ return of_cft(seq->private);
+}
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
+static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
+{
+ return of_css(seq->private);
+}
-struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
- struct cgroup_subsys *ss);
-struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
- struct cgroup_subsys *ss);
+/*
+ * Name / path handling functions. All are thin wrappers around the kernfs
+ * counterparts and can be called under any context.
+ */
-#else /* !CONFIG_CGROUPS */
+static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
+{
+ return kernfs_name(cgrp->kn, buf, buflen);
+}
-struct cgroup_subsys_state;
+static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
+ size_t buflen)
+{
+ return kernfs_path(cgrp->kn, buf, buflen);
+}
-static inline int cgroup_init_early(void) { return 0; }
-static inline int cgroup_init(void) { return 0; }
-static inline void cgroup_fork(struct task_struct *p) {}
-static inline void cgroup_post_fork(struct task_struct *p) {}
-static inline void cgroup_exit(struct task_struct *p) {}
+static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
+{
+ pr_cont_kernfs_name(cgrp->kn);
+}
-static inline int cgroupstats_build(struct cgroupstats *stats,
- struct dentry *dentry)
+static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
{
- return -EINVAL;
+ pr_cont_kernfs_path(cgrp->kn);
}
-static inline void css_put(struct cgroup_subsys_state *css) {}
+#else /* !CONFIG_CGROUPS */
+
+struct cgroup_subsys_state;
-/* No cgroups - nothing to do */
+static inline void css_put(struct cgroup_subsys_state *css) {}
static inline int cgroup_attach_task_all(struct task_struct *from,
- struct task_struct *t)
-{
- return 0;
-}
+ struct task_struct *t) { return 0; }
+static inline int cgroupstats_build(struct cgroupstats *stats,
+ struct dentry *dentry) { return -EINVAL; }
+
+static inline void cgroup_fork(struct task_struct *p) {}
+static inline void cgroup_post_fork(struct task_struct *p) {}
+static inline void cgroup_exit(struct task_struct *p) {}
+
+static inline int cgroup_init_early(void) { return 0; }
+static inline int cgroup_init(void) { return 0; }
#endif /* !CONFIG_CGROUPS */
extern struct files_struct init_files;
extern struct fs_struct init_fs;
-#ifdef CONFIG_CGROUPS
-#define INIT_GROUP_RWSEM(sig) \
- .group_rwsem = __RWSEM_INITIALIZER(sig.group_rwsem),
-#else
-#define INIT_GROUP_RWSEM(sig)
-#endif
-
#ifdef CONFIG_CPUSETS
#define INIT_CPUSET_SEQ(tsk) \
.mems_allowed_seq = SEQCNT_ZERO(tsk.mems_allowed_seq),
}, \
.cred_guard_mutex = \
__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
- INIT_GROUP_RWSEM(sig) \
}
extern struct nsproxy init_nsproxy;
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
+struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
unsigned int flags, void *priv);
static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
{ return NULL; }
+static inline struct inode *
+kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
+{ return NULL; }
+
static inline struct kernfs_root *
kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
void *priv)
#include <linux/uidgid.h>
#include <linux/gfp.h>
#include <linux/magic.h>
+#include <linux/cgroup-defs.h>
#include <asm/processor.h>
unsigned audit_tty_log_passwd;
struct tty_audit_buf *tty_audit_buf;
#endif
-#ifdef CONFIG_CGROUPS
- /*
- * group_rwsem prevents new tasks from entering the threadgroup and
- * member tasks from exiting,a more specifically, setting of
- * PF_EXITING. fork and exit paths are protected with this rwsem
- * using threadgroup_change_begin/end(). Users which require
- * threadgroup to remain stable should use threadgroup_[un]lock()
- * which also takes care of exec path. Currently, cgroup is the
- * only user.
- */
- struct rw_semaphore group_rwsem;
-#endif
oom_flags_t oom_flags;
short oom_score_adj; /* OOM kill score adjustment */
spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
}
-#ifdef CONFIG_CGROUPS
-static inline void threadgroup_change_begin(struct task_struct *tsk)
-{
- down_read(&tsk->signal->group_rwsem);
-}
-static inline void threadgroup_change_end(struct task_struct *tsk)
-{
- up_read(&tsk->signal->group_rwsem);
-}
-
/**
- * threadgroup_lock - lock threadgroup
- * @tsk: member task of the threadgroup to lock
- *
- * Lock the threadgroup @tsk belongs to. No new task is allowed to enter
- * and member tasks aren't allowed to exit (as indicated by PF_EXITING) or
- * change ->group_leader/pid. This is useful for cases where the threadgroup
- * needs to stay stable across blockable operations.
- *
- * fork and exit paths explicitly call threadgroup_change_{begin|end}() for
- * synchronization. While held, no new task will be added to threadgroup
- * and no existing live task will have its PF_EXITING set.
+ * threadgroup_change_begin - mark the beginning of changes to a threadgroup
+ * @tsk: task causing the changes
*
- * de_thread() does threadgroup_change_{begin|end}() when a non-leader
- * sub-thread becomes a new leader.
+ * All operations which modify a threadgroup - a new thread joining the
+ * group, death of a member thread (the assertion of PF_EXITING) and
+ * exec(2) dethreading the process and replacing the leader - are wrapped
+ * by threadgroup_change_{begin|end}(). This is to provide a place which
+ * subsystems needing threadgroup stability can hook into for
+ * synchronization.
*/
-static inline void threadgroup_lock(struct task_struct *tsk)
+static inline void threadgroup_change_begin(struct task_struct *tsk)
{
- down_write(&tsk->signal->group_rwsem);
+ might_sleep();
+ cgroup_threadgroup_change_begin(tsk);
}
/**
- * threadgroup_unlock - unlock threadgroup
- * @tsk: member task of the threadgroup to unlock
+ * threadgroup_change_end - mark the end of changes to a threadgroup
+ * @tsk: task causing the changes
*
- * Reverse threadgroup_lock().
+ * See threadgroup_change_begin().
*/
-static inline void threadgroup_unlock(struct task_struct *tsk)
+static inline void threadgroup_change_end(struct task_struct *tsk)
{
- up_write(&tsk->signal->group_rwsem);
+ cgroup_threadgroup_change_end(tsk);
}
-#else
-static inline void threadgroup_change_begin(struct task_struct *tsk) {}
-static inline void threadgroup_change_end(struct task_struct *tsk) {}
-static inline void threadgroup_lock(struct task_struct *tsk) {}
-static inline void threadgroup_unlock(struct task_struct *tsk) {}
-#endif
#ifndef __HAVE_THREAD_FUNCTIONS
menuconfig CGROUPS
bool "Control Group support"
select KERNFS
+ select PERCPU_RWSEM
help
This option adds support for grouping sets of processes together, for
use with process control subsystems such as Cpusets, CFS, memory
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>
+#include <linux/percpu-rwsem.h>
#include <linux/string.h>
#include <linux/sort.h>
#include <linux/kmod.h>
*/
static DEFINE_SPINLOCK(release_agent_path_lock);
+struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
+
#define cgroup_assert_mutex_or_rcu_locked() \
rcu_lockdep_assert(rcu_read_lock_held() || \
lockdep_is_held(&cgroup_mutex), \
static bool cgroup_legacy_files_on_dfl;
/* some controllers are not supported in the default hierarchy */
-static unsigned int cgrp_dfl_root_inhibit_ss_mask;
+static unsigned long cgrp_dfl_root_inhibit_ss_mask;
/* The list of hierarchy roots */
*/
static u64 css_serial_nr_next = 1;
-/* This flag indicates whether tasks in the fork and exit paths should
- * check for fork/exit handlers to call. This avoids us having to do
- * extra work in the fork/exit path if none of the subsystems need to
- * be called.
+/*
+ * These bitmask flags indicate whether tasks in the fork and exit paths have
+ * fork/exit handlers to call. This avoids us having to do extra work in the
+ * fork/exit path to check which subsystems have fork/exit callbacks.
*/
-static int need_forkexit_callback __read_mostly;
+static unsigned long have_fork_callback __read_mostly;
+static unsigned long have_exit_callback __read_mostly;
static struct cftype cgroup_dfl_base_files[];
static struct cftype cgroup_legacy_base_files[];
static int rebind_subsystems(struct cgroup_root *dst_root,
- unsigned int ss_mask);
+ unsigned long ss_mask);
static int cgroup_destroy_locked(struct cgroup *cgrp);
static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
bool visible);
* @cgrp: the cgroup of interest
* @ss: the subsystem of interest (%NULL returns @cgrp->self)
*
- * Similar to cgroup_css() but returns the effctive css, which is defined
+ * Similar to cgroup_css() but returns the effective css, which is defined
* as the matching css of the nearest ancestor including self which has @ss
* enabled. If @ss is associated with the hierarchy @cgrp is on, this
* function is guaranteed to return non-NULL css.
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
(((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
+/**
+ * for_each_subsys_which - filter for_each_subsys with a bitmask
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ * @ss_maskp: a pointer to the bitmask
+ *
+ * The block will only run for cases where the ssid-th bit (1 << ssid) of
+ * mask is set to 1.
+ */
+#define for_each_subsys_which(ss, ssid, ss_maskp) \
+ if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \
+ (ssid) = 0; \
+ else \
+ for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \
+ if (((ss) = cgroup_subsys[ssid]) && false) \
+ break; \
+ else
+
/* iterate across the hierarchies */
#define for_each_root(root) \
list_for_each_entry((root), &cgroup_roots, root_list)
static void cgroup_free_root(struct cgroup_root *root)
{
if (root) {
- /* hierarhcy ID shoulid already have been released */
+ /* hierarchy ID should already have been released */
WARN_ON_ONCE(root->hierarchy_id);
idr_destroy(&root->cgroup_idr);
* update of a tasks cgroup pointer by cgroup_attach_task()
*/
-static int cgroup_populate_dir(struct cgroup *cgrp, unsigned int subsys_mask);
+static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask);
static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
static const struct file_operations proc_cgroupstats_operations;
* @subtree_control is to be applied to @cgrp. The returned mask is always
* a superset of @subtree_control and follows the usual hierarchy rules.
*/
-static unsigned int cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
- unsigned int subtree_control)
+static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp,
+ unsigned long subtree_control)
{
struct cgroup *parent = cgroup_parent(cgrp);
- unsigned int cur_ss_mask = subtree_control;
+ unsigned long cur_ss_mask = subtree_control;
struct cgroup_subsys *ss;
int ssid;
return cur_ss_mask;
while (true) {
- unsigned int new_ss_mask = cur_ss_mask;
+ unsigned long new_ss_mask = cur_ss_mask;
- for_each_subsys(ss, ssid)
- if (cur_ss_mask & (1 << ssid))
- new_ss_mask |= ss->depends_on;
+ for_each_subsys_which(ss, ssid, &cur_ss_mask)
+ new_ss_mask |= ss->depends_on;
/*
* Mask out subsystems which aren't available. This can
* @cgrp: target cgroup
* @subsys_mask: mask of the subsystem ids whose files should be removed
*/
-static void cgroup_clear_dir(struct cgroup *cgrp, unsigned int subsys_mask)
+static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask)
{
struct cgroup_subsys *ss;
int i;
}
}
-static int rebind_subsystems(struct cgroup_root *dst_root, unsigned int ss_mask)
+static int rebind_subsystems(struct cgroup_root *dst_root,
+ unsigned long ss_mask)
{
struct cgroup_subsys *ss;
- unsigned int tmp_ss_mask;
+ unsigned long tmp_ss_mask;
int ssid, i, ret;
lockdep_assert_held(&cgroup_mutex);
- for_each_subsys(ss, ssid) {
- if (!(ss_mask & (1 << ssid)))
- continue;
-
+ for_each_subsys_which(ss, ssid, &ss_mask) {
/* if @ss has non-root csses attached to it, can't move */
if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)))
return -EBUSY;
* Just warn about it and continue.
*/
if (cgrp_dfl_root_visible) {
- pr_warn("failed to create files (%d) while rebinding 0x%x to default root\n",
+ pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n",
ret, ss_mask);
pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
}
* Nothing can fail from this point on. Remove files for the
* removed subsystems and rebind each subsystem.
*/
- for_each_subsys(ss, ssid)
- if (ss_mask & (1 << ssid))
- cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
+ for_each_subsys_which(ss, ssid, &ss_mask)
+ cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
- for_each_subsys(ss, ssid) {
+ for_each_subsys_which(ss, ssid, &ss_mask) {
struct cgroup_root *src_root;
struct cgroup_subsys_state *css;
struct css_set *cset;
- if (!(ss_mask & (1 << ssid)))
- continue;
-
src_root = ss->root;
css = cgroup_css(&src_root->cgrp, ss);
}
struct cgroup_sb_opts {
- unsigned int subsys_mask;
+ unsigned long subsys_mask;
unsigned int flags;
char *release_agent;
bool cpuset_clone_children;
{
char *token, *o = data;
bool all_ss = false, one_ss = false;
- unsigned int mask = -1U;
+ unsigned long mask = -1UL;
struct cgroup_subsys *ss;
int nr_opts = 0;
int i;
int ret = 0;
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
struct cgroup_sb_opts opts;
- unsigned int added_mask, removed_mask;
+ unsigned long added_mask, removed_mask;
if (root == &cgrp_dfl_root) {
pr_err("remount is not allowed\n");
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
}
-static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask)
+static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
{
LIST_HEAD(tmp_links);
struct cgroup *root_cgrp = &root->cgrp;
lockdep_assert_held(&css_set_rwsem);
/*
- * We are synchronized through threadgroup_lock() against PF_EXITING
- * setting such that we can't race against cgroup_exit() changing the
- * css_set to init_css_set and dropping the old one.
+ * We are synchronized through cgroup_threadgroup_rwsem against
+ * PF_EXITING setting such that we can't race against cgroup_exit()
+ * changing the css_set to init_css_set and dropping the old one.
*/
WARN_ON_ONCE(tsk->flags & PF_EXITING);
old_cset = task_css_set(tsk);
* @src_cset and add it to @preloaded_csets, which should later be cleaned
* up by cgroup_migrate_finish().
*
- * This function may be called without holding threadgroup_lock even if the
- * target is a process. Threads may be created and destroyed but as long
- * as cgroup_mutex is not dropped, no new css_set can be put into play and
- * the preloaded css_sets are guaranteed to cover all migrations.
+ * This function may be called without holding cgroup_threadgroup_rwsem
+ * even if the target is a process. Threads may be created and destroyed
+ * but as long as cgroup_mutex is not dropped, no new css_set can be put
+ * into play and the preloaded css_sets are guaranteed to cover all
+ * migrations.
*/
static void cgroup_migrate_add_src(struct css_set *src_cset,
struct cgroup *dst_cgrp,
* @threadgroup: whether @leader points to the whole process or a single task
*
* Migrate a process or task denoted by @leader to @cgrp. If migrating a
- * process, the caller must be holding threadgroup_lock of @leader. The
+ * process, the caller must be holding cgroup_threadgroup_rwsem. The
* caller is also responsible for invoking cgroup_migrate_add_src() and
* cgroup_migrate_prepare_dst() on the targets before invoking this
* function and following up with cgroup_migrate_finish().
* @leader: the task or the leader of the threadgroup to be attached
* @threadgroup: attach the whole threadgroup?
*
- * Call holding cgroup_mutex and threadgroup_lock of @leader.
+ * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
*/
static int cgroup_attach_task(struct cgroup *dst_cgrp,
struct task_struct *leader, bool threadgroup)
return ret;
}
+static int cgroup_procs_write_permission(struct task_struct *task,
+ struct cgroup *dst_cgrp,
+ struct kernfs_open_file *of)
+{
+ const struct cred *cred = current_cred();
+ const struct cred *tcred = get_task_cred(task);
+ int ret = 0;
+
+ /*
+ * even if we're attaching all tasks in the thread group, we only
+ * need to check permissions on one of them.
+ */
+ if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+ !uid_eq(cred->euid, tcred->uid) &&
+ !uid_eq(cred->euid, tcred->suid))
+ ret = -EACCES;
+
+ if (!ret && cgroup_on_dfl(dst_cgrp)) {
+ struct super_block *sb = of->file->f_path.dentry->d_sb;
+ struct cgroup *cgrp;
+ struct inode *inode;
+
+ down_read(&css_set_rwsem);
+ cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ up_read(&css_set_rwsem);
+
+ while (!cgroup_is_descendant(dst_cgrp, cgrp))
+ cgrp = cgroup_parent(cgrp);
+
+ ret = -ENOMEM;
+ inode = kernfs_get_inode(sb, cgrp->procs_kn);
+ if (inode) {
+ ret = inode_permission(inode, MAY_WRITE);
+ iput(inode);
+ }
+ }
+
+ put_cred(tcred);
+ return ret;
+}
+
/*
* Find the task_struct of the task to attach by vpid and pass it along to the
* function to attach either it or all tasks in its threadgroup. Will lock
size_t nbytes, loff_t off, bool threadgroup)
{
struct task_struct *tsk;
- const struct cred *cred = current_cred(), *tcred;
struct cgroup *cgrp;
pid_t pid;
int ret;
if (!cgrp)
return -ENODEV;
-retry_find_task:
+ percpu_down_write(&cgroup_threadgroup_rwsem);
rcu_read_lock();
if (pid) {
tsk = find_task_by_vpid(pid);
if (!tsk) {
- rcu_read_unlock();
ret = -ESRCH;
- goto out_unlock_cgroup;
+ goto out_unlock_rcu;
}
- /*
- * even if we're attaching all tasks in the thread group, we
- * only need to check permissions on one of them.
- */
- tcred = __task_cred(tsk);
- if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
- !uid_eq(cred->euid, tcred->uid) &&
- !uid_eq(cred->euid, tcred->suid)) {
- rcu_read_unlock();
- ret = -EACCES;
- goto out_unlock_cgroup;
- }
- } else
+ } else {
tsk = current;
+ }
if (threadgroup)
tsk = tsk->group_leader;
*/
if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
ret = -EINVAL;
- rcu_read_unlock();
- goto out_unlock_cgroup;
+ goto out_unlock_rcu;
}
get_task_struct(tsk);
rcu_read_unlock();
- threadgroup_lock(tsk);
- if (threadgroup) {
- if (!thread_group_leader(tsk)) {
- /*
- * a race with de_thread from another thread's exec()
- * may strip us of our leadership, if this happens,
- * there is no choice but to throw this task away and
- * try again; this is
- * "double-double-toil-and-trouble-check locking".
- */
- threadgroup_unlock(tsk);
- put_task_struct(tsk);
- goto retry_find_task;
- }
- }
-
- ret = cgroup_attach_task(cgrp, tsk, threadgroup);
-
- threadgroup_unlock(tsk);
+ ret = cgroup_procs_write_permission(tsk, cgrp, of);
+ if (!ret)
+ ret = cgroup_attach_task(cgrp, tsk, threadgroup);
put_task_struct(tsk);
-out_unlock_cgroup:
+ goto out_unlock_threadgroup;
+
+out_unlock_rcu:
+ rcu_read_unlock();
+out_unlock_threadgroup:
+ percpu_up_write(&cgroup_threadgroup_rwsem);
cgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
return 0;
}
-static void cgroup_print_ss_mask(struct seq_file *seq, unsigned int ss_mask)
+static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask)
{
struct cgroup_subsys *ss;
bool printed = false;
int ssid;
- for_each_subsys(ss, ssid) {
- if (ss_mask & (1 << ssid)) {
- if (printed)
- seq_putc(seq, ' ');
- seq_printf(seq, "%s", ss->name);
- printed = true;
- }
+ for_each_subsys_which(ss, ssid, &ss_mask) {
+ if (printed)
+ seq_putc(seq, ' ');
+ seq_printf(seq, "%s", ss->name);
+ printed = true;
}
if (printed)
seq_putc(seq, '\n');
lockdep_assert_held(&cgroup_mutex);
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+
/* look up all csses currently attached to @cgrp's subtree */
down_read(&css_set_rwsem);
css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) {
goto out_finish;
last_task = task;
- threadgroup_lock(task);
- /* raced against de_thread() from another thread? */
- if (!thread_group_leader(task)) {
- threadgroup_unlock(task);
- put_task_struct(task);
- continue;
- }
-
ret = cgroup_migrate(src_cset->dfl_cgrp, task, true);
- threadgroup_unlock(task);
put_task_struct(task);
if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret))
out_finish:
cgroup_migrate_finish(&preloaded_csets);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
return ret;
}
char *buf, size_t nbytes,
loff_t off)
{
- unsigned int enable = 0, disable = 0;
- unsigned int css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
+ unsigned long enable = 0, disable = 0;
+ unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
struct cgroup *cgrp, *child;
struct cgroup_subsys *ss;
char *tok;
*/
buf = strstrip(buf);
while ((tok = strsep(&buf, " "))) {
+ unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask;
+
if (tok[0] == '\0')
continue;
- for_each_subsys(ss, ssid) {
- if (ss->disabled || strcmp(tok + 1, ss->name) ||
- ((1 << ss->id) & cgrp_dfl_root_inhibit_ss_mask))
+ for_each_subsys_which(ss, ssid, &tmp_ss_mask) {
+ if (ss->disabled || strcmp(tok + 1, ss->name))
continue;
if (*tok == '+') {
* still around. In such cases, wait till it's gone using
* offline_waitq.
*/
- for_each_subsys(ss, ssid) {
- if (!(css_enable & (1 << ssid)))
- continue;
-
+ for_each_subsys_which(ss, ssid, &css_enable) {
cgroup_for_each_live_child(child, cgrp) {
DEFINE_WAIT(wait);
return ret;
}
- if (cft->seq_show == cgroup_populated_show)
+ if (cft->write == cgroup_procs_write)
+ cgrp->procs_kn = kn;
+ else if (cft->seq_show == cgroup_populated_show)
cgrp->populated_kn = kn;
return 0;
}
*
* On failure, no file is added.
*/
-static int cgroup_populate_dir(struct cgroup *cgrp, unsigned int subsys_mask)
+static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
{
struct cgroup_subsys *ss;
int i, ret = 0;
* init_css_set is in the subsystem's root cgroup. */
init_css_set.subsys[ss->id] = css;
- need_forkexit_callback |= ss->fork || ss->exit;
+ have_fork_callback |= (bool)ss->fork << ss->id;
+ have_exit_callback |= (bool)ss->exit << ss->id;
/* At system boot, before all subsystems have been
* registered, no tasks have been forked, so we don't
unsigned long key;
int ssid, err;
+ BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
* css_set; otherwise, @child might change state between ->fork()
* and addition to css_set.
*/
- if (need_forkexit_callback) {
- for_each_subsys(ss, i)
- if (ss->fork)
- ss->fork(child);
- }
+ for_each_subsys_which(ss, i, &have_fork_callback)
+ ss->fork(child);
}
/**
cset = task_css_set(tsk);
RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
- if (need_forkexit_callback) {
- /* see cgroup_post_fork() for details */
- for_each_subsys(ss, i) {
- if (ss->exit) {
- struct cgroup_subsys_state *old_css = cset->subsys[i];
- struct cgroup_subsys_state *css = task_css(tsk, i);
+ /* see cgroup_post_fork() for details */
+ for_each_subsys_which(ss, i, &have_exit_callback) {
+ struct cgroup_subsys_state *old_css = cset->subsys[i];
+ struct cgroup_subsys_state *css = task_css(tsk, i);
- ss->exit(css, old_css, tsk);
- }
- }
+ ss->exit(css, old_css, tsk);
}
if (put_cset)
tty_audit_fork(sig);
sched_autogroup_fork(sig);
-#ifdef CONFIG_CGROUPS
- init_rwsem(&sig->group_rwsem);
-#endif
-
sig->oom_score_adj = current->signal->oom_score_adj;
sig->oom_score_adj_min = current->signal->oom_score_adj_min;
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