Merge branch 'for-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
- threadgroup_lock got reorganized so that its users can pick the
actual locking mechanism to use. Its only user - cgroups - is
updated to use a percpu_rwsem instead of per-process rwsem.
This makes things a bit lighter on hot paths and allows cgroups to
perform and fail multi-task (a process) migrations atomically.
Multi-task migrations are used in several places including the
unified hierarchy.
- Delegation rule and documentation added to unified hierarchy. This
will likely be the last interface update from the cgroup core side
for unified hierarchy before lifting the devel mask.
- Some groundwork for the pids controller which is scheduled to be
merged in the coming devel cycle.
* 'for-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: add delegation section to unified hierarchy documentation
cgroup: require write perm on common ancestor when moving processes on the default hierarchy
cgroup: separate out cgroup_procs_write_permission() from __cgroup_procs_write()
kernfs: make kernfs_get_inode() public
MAINTAINERS: add a cgroup core co-maintainer
cgroup: fix uninitialised iterator in for_each_subsys_which
cgroup: replace explicit ss_mask checking with for_each_subsys_which
cgroup: use bitmask to filter for_each_subsys
cgroup: add seq_file forward declaration for struct cftype
cgroup: simplify threadgroup locking
sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem
sched, cgroup: reorganize threadgroup locking
cgroup: switch to unsigned long for bitmasks
cgroup: reorganize include/linux/cgroup.h
cgroup: separate out include/linux/cgroup-defs.h
cgroup: fix some comment typos
diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index eb102fb..86847a7 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -17,15 +17,18 @@
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
@@ -245,9 +248,72 @@
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
@@ -289,7 +355,7 @@
"notify_on_release" do not exist.
-4-2. Other Core Changes
+5-2. Other Core Changes
- None of the mount options is allowed.
@@ -306,14 +372,14 @@
- 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.
@@ -322,7 +388,7 @@
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.
@@ -407,9 +473,9 @@
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
diff --git a/MAINTAINERS b/MAINTAINERS
index 68457d8..c54a674 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2816,6 +2816,7 @@
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
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index af9fa74..6762bfb 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -76,7 +76,6 @@
/*
* 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);
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
new file mode 100644
index 0000000..93755a6
--- /dev/null
+++ b/include/linux/cgroup-defs.h
@@ -0,0 +1,501 @@
+/*
+ * 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 */
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e7da0aa..a593e29 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -11,94 +11,200 @@
#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;
-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 *cset_pos;
+ struct list_head *cset_head;
-extern int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk);
-
-/* 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,
+ struct list_head *task_pos;
+ struct list_head *tasks_head;
+ struct list_head *mg_tasks_head;
};
+
+extern struct cgroup_root cgrp_dfl_root;
+extern struct css_set init_css_set;
+
+#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
+#include <linux/cgroup_subsys.h>
#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.
- *
- * Fields marked with "PI:" are public and immutable and may be accessed
- * directly without synchronization.
+ * Iteration helpers and macros.
*/
-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;
+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);
- /* reference count - access via css_[try]get() and css_put() */
- struct percpu_ref refcnt;
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset);
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset);
- /* PI: the parent css */
- struct cgroup_subsys_state *parent;
+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);
- /* siblings list anchored at the parent's ->children */
- struct list_head sibling;
- struct list_head children;
+/**
+ * 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.
+ *
+ * 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)))
- /*
- * 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;
+/**
+ * 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)))
- unsigned int flags;
+/**
+ * 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)))
- /*
- * 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;
+/**
+ * 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)))
- /* percpu_ref killing and RCU release */
- struct rcu_head rcu_head;
- struct work_struct destroy_work;
-};
-
-/* 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 */
-};
+/*
+ * Inline functions.
+ */
/**
* css_get - obtain a reference on the specified css
@@ -185,309 +291,112 @@
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
+/**
+ * task_css_set_check - obtain a task's css_set with extra access conditions
+ * @task: the task to obtain css_set for
+ * @__c: extra condition expression to be passed to rcu_dereference_check()
*
- * 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
+ * A task's css_set is RCU protected, initialized and exited while holding
+ * task_lock(), and can only be modified while holding both cgroup_mutex
+ * and task_lock() while the task is alive. This macro verifies that the
+ * caller is inside proper critical section and returns @task's css_set.
+ *
+ * The caller can also specify additional allowed conditions via @__c, such
+ * as locks used during the cgroup_subsys::attach() methods.
*/
-
-/* 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;
+#ifdef CONFIG_PROVE_RCU
+extern struct mutex cgroup_mutex;
+extern struct rw_semaphore css_set_rwsem;
+#define task_css_set_check(task, __c) \
+ rcu_dereference_check((task)->cgroups, \
+ lockdep_is_held(&cgroup_mutex) || \
+ lockdep_is_held(&css_set_rwsem) || \
+ ((task)->flags & PF_EXITING) || (__c))
+#else
+#define task_css_set_check(task, __c) \
+ rcu_dereference((task)->cgroups)
#endif
-};
-extern struct cgroup_root cgrp_dfl_root;
-extern struct css_set init_css_set;
+/**
+ * task_css_check - obtain css for (task, subsys) w/ extra access conds
+ * @task: the target task
+ * @subsys_id: the target subsystem ID
+ * @__c: extra condition expression to be passed to rcu_dereference_check()
+ *
+ * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
+ * synchronization rules are the same as task_css_set_check().
+ */
+#define task_css_check(task, subsys_id, __c) \
+ task_css_set_check((task), (__c))->subsys[(subsys_id)]
+
+/**
+ * task_css_set - obtain a task's css_set
+ * @task: the task to obtain css_set for
+ *
+ * See task_css_set_check().
+ */
+static inline struct css_set *task_css_set(struct task_struct *task)
+{
+ return task_css_set_check(task, false);
+}
+
+/**
+ * task_css - obtain css for (task, subsys)
+ * @task: the target task
+ * @subsys_id: the target subsystem ID
+ *
+ * See task_css_check().
+ */
+static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
+ int subsys_id)
+{
+ return task_css_check(task, subsys_id, false);
+}
+
+/**
+ * task_get_css - find and get the css for (task, subsys)
+ * @task: the target task
+ * @subsys_id: the target subsystem ID
+ *
+ * Find the css for the (@task, @subsys_id) combination, increment a
+ * reference on and return it. This function is guaranteed to return a
+ * valid css.
+ */
+static inline struct cgroup_subsys_state *
+task_get_css(struct task_struct *task, int subsys_id)
+{
+ struct cgroup_subsys_state *css;
+
+ rcu_read_lock();
+ while (true) {
+ css = task_css(task, subsys_id);
+ if (likely(css_tryget_online(css)))
+ break;
+ cpu_relax();
+ }
+ rcu_read_unlock();
+ return css;
+}
+
+/**
+ * task_css_is_root - test whether a task belongs to the root css
+ * @task: the target task
+ * @subsys_id: the target subsystem ID
+ *
+ * Test whether @task belongs to the root css on the specified subsystem.
+ * May be invoked in any context.
+ */
+static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
+{
+ return task_css_check(task, subsys_id, true) ==
+ init_css_set.subsys[subsys_id];
+}
+
+static inline struct cgroup *task_cgroup(struct task_struct *task,
+ int subsys_id)
+{
+ return task_css(task, subsys_id)->cgroup;
+}
/**
* cgroup_on_dfl - test whether a cgroup is on the default hierarchy
@@ -604,392 +513,22 @@
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);
-
-/**
- * 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)))
-
-/*
- * 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;
-#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
-
-/**
- * task_css_set_check - obtain a task's css_set with extra access conditions
- * @task: the task to obtain css_set for
- * @__c: extra condition expression to be passed to rcu_dereference_check()
- *
- * A task's css_set is RCU protected, initialized and exited while holding
- * task_lock(), and can only be modified while holding both cgroup_mutex
- * and task_lock() while the task is alive. This macro verifies that the
- * caller is inside proper critical section and returns @task's css_set.
- *
- * The caller can also specify additional allowed conditions via @__c, such
- * as locks used during the cgroup_subsys::attach() methods.
- */
-#ifdef CONFIG_PROVE_RCU
-extern struct mutex cgroup_mutex;
-extern struct rw_semaphore css_set_rwsem;
-#define task_css_set_check(task, __c) \
- rcu_dereference_check((task)->cgroups, \
- lockdep_is_held(&cgroup_mutex) || \
- lockdep_is_held(&css_set_rwsem) || \
- ((task)->flags & PF_EXITING) || (__c))
-#else
-#define task_css_set_check(task, __c) \
- rcu_dereference((task)->cgroups)
-#endif
-
-/**
- * task_css_check - obtain css for (task, subsys) w/ extra access conds
- * @task: the target task
- * @subsys_id: the target subsystem ID
- * @__c: extra condition expression to be passed to rcu_dereference_check()
- *
- * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The
- * synchronization rules are the same as task_css_set_check().
- */
-#define task_css_check(task, subsys_id, __c) \
- task_css_set_check((task), (__c))->subsys[(subsys_id)]
-
-/**
- * task_css_set - obtain a task's css_set
- * @task: the task to obtain css_set for
- *
- * See task_css_set_check().
- */
-static inline struct css_set *task_css_set(struct task_struct *task)
-{
- return task_css_set_check(task, false);
-}
-
-/**
- * task_css - obtain css for (task, subsys)
- * @task: the target task
- * @subsys_id: the target subsystem ID
- *
- * See task_css_check().
- */
-static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
- int subsys_id)
-{
- return task_css_check(task, subsys_id, false);
-}
-
-/**
- * task_get_css - find and get the css for (task, subsys)
- * @task: the target task
- * @subsys_id: the target subsystem ID
- *
- * Find the css for the (@task, @subsys_id) combination, increment a
- * reference on and return it. This function is guaranteed to return a
- * valid css.
- */
-static inline struct cgroup_subsys_state *
-task_get_css(struct task_struct *task, int subsys_id)
-{
- struct cgroup_subsys_state *css;
-
- rcu_read_lock();
- while (true) {
- css = task_css(task, subsys_id);
- if (likely(css_tryget_online(css)))
- break;
- cpu_relax();
- }
- rcu_read_unlock();
- return css;
-}
-
-/**
- * task_css_is_root - test whether a task belongs to the root css
- * @task: the target task
- * @subsys_id: the target subsystem ID
- *
- * Test whether @task belongs to the root css on the specified subsystem.
- * May be invoked in any context.
- */
-static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
-{
- return task_css_check(task, subsys_id, true) ==
- init_css_set.subsys[subsys_id];
-}
-
-static inline struct cgroup *task_cgroup(struct task_struct *task,
- int subsys_id)
-{
- 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
- *
- * 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.
- *
- * 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
- *
- * 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)))
-
-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
- *
- * 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)))
-
-bool css_has_online_children(struct cgroup_subsys_state *css);
-
-/* 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;
-
- struct list_head *task_pos;
- struct list_head *tasks_head;
- struct list_head *mg_tasks_head;
-};
-
-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);
-
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
-
-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);
-
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
-static inline int cgroup_init_early(void) { return 0; }
-static inline int cgroup_init(void) { return 0; }
+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; }
+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 cgroupstats_build(struct cgroupstats *stats,
- struct dentry *dentry)
-{
- return -EINVAL;
-}
-
-static inline void css_put(struct cgroup_subsys_state *css) {}
-
-/* No cgroups - nothing to do */
-static inline int cgroup_attach_task_all(struct task_struct *from,
- struct task_struct *t)
-{
- return 0;
-}
+static inline int cgroup_init_early(void) { return 0; }
+static inline int cgroup_init(void) { return 0; }
#endif /* !CONFIG_CGROUPS */
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index bb9b075..e8493fe 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -25,13 +25,6 @@
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),
@@ -55,7 +48,6 @@
}, \
.cred_guard_mutex = \
__MUTEX_INITIALIZER(sig.cred_guard_mutex), \
- INIT_GROUP_RWSEM(sig) \
}
extern struct nsproxy init_nsproxy;
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 71ecdab..e6b2f7d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -277,6 +277,7 @@
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);
@@ -352,6 +353,10 @@
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)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 93ed0b6..a09ece3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -58,6 +58,7 @@
#include <linux/uidgid.h>
#include <linux/gfp.h>
#include <linux/magic.h>
+#include <linux/cgroup-defs.h>
#include <asm/processor.h>
@@ -755,18 +756,6 @@
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 */
@@ -2725,54 +2714,34 @@
spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
}
-#ifdef CONFIG_CGROUPS
+/**
+ * threadgroup_change_begin - mark the beginning of changes to a threadgroup
+ * @tsk: task causing the changes
+ *
+ * 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_change_begin(struct task_struct *tsk)
{
- down_read(&tsk->signal->group_rwsem);
+ might_sleep();
+ cgroup_threadgroup_change_begin(tsk);
}
+
+/**
+ * threadgroup_change_end - mark the end of changes to a threadgroup
+ * @tsk: task causing the changes
+ *
+ * See threadgroup_change_begin().
+ */
static inline void threadgroup_change_end(struct task_struct *tsk)
{
- up_read(&tsk->signal->group_rwsem);
+ cgroup_threadgroup_change_end(tsk);
}
-/**
- * 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.
- *
- * de_thread() does threadgroup_change_{begin|end}() when a non-leader
- * sub-thread becomes a new leader.
- */
-static inline void threadgroup_lock(struct task_struct *tsk)
-{
- down_write(&tsk->signal->group_rwsem);
-}
-
-/**
- * threadgroup_unlock - unlock threadgroup
- * @tsk: member task of the threadgroup to unlock
- *
- * Reverse threadgroup_lock().
- */
-static inline void threadgroup_unlock(struct task_struct *tsk)
-{
- up_write(&tsk->signal->group_rwsem);
-}
-#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
#define task_thread_info(task) ((struct thread_info *)(task)->stack)
diff --git a/init/Kconfig b/init/Kconfig
index f0c2e68..7d1ffd2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -924,6 +924,7 @@
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
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 469dd54..9ef9fc8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -46,6 +46,7 @@
#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>
@@ -103,6 +104,8 @@
*/
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), \
@@ -156,7 +159,7 @@
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 */
@@ -175,18 +178,19 @@
*/
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);
@@ -261,7 +265,7 @@
* @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.
@@ -409,6 +413,24 @@
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)
@@ -882,7 +904,7 @@
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);
@@ -998,7 +1020,7 @@
* 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;
@@ -1068,11 +1090,11 @@
* @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;
@@ -1082,11 +1104,10 @@
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
@@ -1200,7 +1221,7 @@
* @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;
@@ -1215,18 +1236,16 @@
}
}
-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;
@@ -1253,7 +1272,7 @@
* 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");
}
@@ -1263,18 +1282,14 @@
* 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);
@@ -1338,7 +1353,7 @@
}
struct cgroup_sb_opts {
- unsigned int subsys_mask;
+ unsigned long subsys_mask;
unsigned int flags;
char *release_agent;
bool cpuset_clone_children;
@@ -1351,7 +1366,7 @@
{
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;
@@ -1495,7 +1510,7 @@
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");
@@ -1641,7 +1656,7 @@
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;
@@ -2052,9 +2067,9 @@
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);
@@ -2111,10 +2126,11 @@
* @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,
@@ -2217,7 +2233,7 @@
* @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().
@@ -2345,7 +2361,7 @@
* @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)
@@ -2376,6 +2392,47 @@
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
@@ -2385,7 +2442,6 @@
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;
@@ -2397,29 +2453,17 @@
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;
@@ -2431,35 +2475,23 @@
*/
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;
}
@@ -2542,19 +2574,17 @@
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');
@@ -2606,6 +2636,8 @@
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)) {
@@ -2661,17 +2693,8 @@
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))
@@ -2681,6 +2704,7 @@
out_finish:
cgroup_migrate_finish(&preloaded_csets);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
return ret;
}
@@ -2689,8 +2713,8 @@
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;
@@ -2702,11 +2726,12 @@
*/
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 == '+') {
@@ -2793,10 +2818,7 @@
* 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);
@@ -3087,7 +3109,9 @@
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;
}
@@ -4322,7 +4346,7 @@
*
* 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;
@@ -4931,7 +4955,8 @@
* 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
@@ -4989,6 +5014,7 @@
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));
@@ -5241,11 +5267,8 @@
* 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);
}
/**
@@ -5289,16 +5312,12 @@
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)
diff --git a/kernel/fork.c b/kernel/fork.c
index 4c95cb3..1bfefc6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1141,10 +1141,6 @@
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;