#include <linux/percpu-refcount.h>
#include <linux/seq_file.h>
#include <linux/kernfs.h>
+#include <linux/wait.h>
#ifdef CONFIG_CGROUPS
/* the parent css */
struct cgroup_subsys_state *parent;
- unsigned long flags;
+ /*
+ * 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;
/* percpu_ref killing and RCU release */
struct rcu_head rcu_head;
}
/**
- * css_tryget - try to obtain a reference on the specified css
+ * css_tryget_online - try to obtain a reference on the specified css if online
* @css: target css
*
- * Obtain a reference on @css if it's alive. The caller naturally needs to
- * ensure that @css is accessible but doesn't have to be holding a
+ * Obtain a reference on @css if it's online. The caller naturally needs
+ * to ensure that @css is accessible but doesn't have to be holding a
* reference on it - IOW, RCU protected access is good enough for this
* function. Returns %true if a reference count was successfully obtained;
* %false otherwise.
*/
-static inline bool css_tryget(struct cgroup_subsys_state *css)
+static inline bool css_tryget_online(struct cgroup_subsys_state *css)
{
if (css->flags & CSS_ROOT)
return true;
- return percpu_ref_tryget(&css->refcnt);
+ return percpu_ref_tryget_live(&css->refcnt);
}
/**
* css_put - put a css reference
* @css: target css
*
- * Put a reference obtained via css_get() and css_tryget().
+ * Put a reference obtained via css_get() and css_tryget_online().
*/
static inline void css_put(struct cgroup_subsys_state *css)
{
* specified at mount time and thus is implemented here.
*/
CGRP_CPUSET_CLONE_CHILDREN,
- /* see the comment above CGRP_ROOT_SANE_BEHAVIOR for details */
- CGRP_SANE_BEHAVIOR,
};
struct cgroup {
/*
* idr allocated in-hierarchy ID.
*
- * The ID of the root cgroup is always 0, and a new cgroup
- * will be assigned with a smallest available 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.
*/
/* the number of attached css's */
int nr_css;
+ /*
+ * 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;
+
atomic_t refcnt;
/*
struct cgroup *parent; /* my parent */
struct kernfs_node *kn; /* cgroup kernfs entry */
+ struct kernfs_node *control_kn; /* kn for "cgroup.subtree_control" */
+ struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
/*
* Monotonically increasing unique serial number which defines a
u64 serial_nr;
/* the bitmask of subsystems enabled on the child cgroups */
- unsigned long child_subsys_mask;
+ unsigned int child_subsys_mask;
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
*/
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];
+
/*
* Linked list running through all cgroups that can
* potentially be reaped by the release agent. Protected by
/* For css percpu_ref killing and RCU-protected deletion */
struct rcu_head rcu_head;
struct work_struct destroy_work;
+
+ /* used to wait for offlining of csses */
+ wait_queue_head_t offline_waitq;
};
#define MAX_CGROUP_ROOT_NAMELEN 64
*
* - "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.
+ *
* - If mount is requested with sane_behavior but without any
* subsystem, the default unified hierarchy is mounted.
*
struct kernfs_root *kf_root;
/* The bitmask of subsystems attached to this hierarchy */
- unsigned long subsys_mask;
+ unsigned int subsys_mask;
/* Unique id for this hierarchy. */
int hierarchy_id;
struct list_head root_list;
/* Hierarchy-specific flags */
- unsigned long flags;
+ unsigned int flags;
/* IDs for cgroups in this hierarchy */
struct idr cgroup_idr;
*/
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
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;
};
/*
* The maximum length of string, excluding trailing nul, that can
- * be passed to write_string. If < PAGE_SIZE-1, PAGE_SIZE-1 is
- * assumed.
+ * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
*/
size_t max_write_len;
int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,
s64 val);
- /*
- * write_string() is passed a nul-terminated kernelspace
- * buffer of maximum length determined by max_write_len.
- * Returns 0 or -ve error code.
- */
- int (*write_string)(struct cgroup_subsys_state *css, struct cftype *cft,
- char *buffer);
/*
* trigger() callback can be used to get some kick from the
* userspace, when the actual string written is not important
*/
int (*trigger)(struct cgroup_subsys_state *css, unsigned int event);
+ /*
+ * 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;
static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
{
return 0;
}
-static inline struct cftype *seq_cft(struct seq_file *seq)
+/* cft/css accessors for cftype->write() operation */
+static inline struct cftype *of_cft(struct kernfs_open_file *of)
{
- struct kernfs_open_file *of = seq->private;
-
return of->kn->priv;
}
-struct cgroup_subsys_state *seq_css(struct seq_file *seq);
+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
/* 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.
return task_css_check(task, subsys_id, false);
}
+/**
+ * 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)
{
/* A css_task_iter should be treated as an opaque object */
struct css_task_iter {
- struct cgroup_subsys_state *origin_css;
- struct list_head *cset_link;
- struct list_head *task;
+ 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,
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 *css_tryget_from_dir(struct dentry *dentry,
- struct cgroup_subsys *ss);
+struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss);
#else /* !CONFIG_CGROUPS */
projects / linux-2.6-block.git / blobdiff