*/
#include <linux/sched.h>
-#include <linux/kref.h>
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
#include <linux/cgroupstats.h>
#include <linux/prio_heap.h>
+#include <linux/rwsem.h>
#ifdef CONFIG_CGROUPS
struct cgroupfs_root;
struct cgroup_subsys;
struct inode;
+struct cgroup;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
-extern void cgroup_init_smp(void);
extern void cgroup_lock(void);
+extern bool cgroup_lock_live_group(struct cgroup *cgrp);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
extern void cgroup_fork_callbacks(struct task_struct *p);
* hierarchy structure */
struct cgroup *cgroup;
- /* State maintained by the cgroup system to allow
- * subsystems to be "busy". Should be accessed via css_get()
- * and css_put() */
+ /* State maintained by the cgroup system to allow subsystems
+ * to be "busy". Should be accessed via css_get(),
+ * css_tryget() and and css_put(). */
atomic_t refcnt;
/* bits in struct cgroup_subsys_state flags field */
enum {
CSS_ROOT, /* This CSS is the root of the subsystem */
+ CSS_REMOVED, /* This CSS is dead */
};
/*
- * Call css_get() to hold a reference on the cgroup;
- *
+ * Call css_get() to hold a reference on the css; it can be used
+ * for a reference obtained via:
+ * - an existing ref-counted reference to the css
+ * - task->cgroups for a locked task
*/
static inline void css_get(struct cgroup_subsys_state *css)
if (!test_bit(CSS_ROOT, &css->flags))
atomic_inc(&css->refcnt);
}
+
+static inline bool css_is_removed(struct cgroup_subsys_state *css)
+{
+ return test_bit(CSS_REMOVED, &css->flags);
+}
+
+/*
+ * Call css_tryget() to take a reference on a css if your existing
+ * (known-valid) reference isn't already ref-counted. Returns false if
+ * the css has been destroyed.
+ */
+
+static inline bool css_tryget(struct cgroup_subsys_state *css)
+{
+ if (test_bit(CSS_ROOT, &css->flags))
+ return true;
+ while (!atomic_inc_not_zero(&css->refcnt)) {
+ if (test_bit(CSS_REMOVED, &css->flags))
+ return false;
+ }
+ return true;
+}
+
/*
* css_put() should be called to release a reference taken by
- * css_get()
+ * css_get() or css_tryget()
*/
extern void __css_put(struct cgroup_subsys_state *css);
struct list_head children; /* my children */
struct cgroup *parent; /* my parent */
- struct dentry *dentry; /* cgroup fs entry */
+ struct dentry *dentry; /* cgroup fs entry, RCU protected */
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
* release_list_lock
*/
struct list_head release_list;
+
+ /* pids_mutex protects the fields below */
+ struct rw_semaphore pids_mutex;
+ /* Array of process ids in the cgroup */
+ pid_t *tasks_pids;
+ /* How many files are using the current tasks_pids array */
+ int pids_use_count;
+ /* Length of the current tasks_pids array */
+ int pids_length;
+
+ /* For RCU-protected deletion */
+ struct rcu_head rcu_head;
};
/* A css_set is a structure holding pointers to a set of
struct css_set {
/* Reference count */
- struct kref ref;
+ atomic_t refcount;
/*
- * List running through all cgroup groups. Protected by
- * css_set_lock
+ * List running through all cgroup groups in the same hash
+ * slot. Protected by css_set_lock
*/
- struct list_head list;
+ struct hlist_node hlist;
/*
* List running through all tasks using this cgroup
* during subsystem registration (at boot time).
*/
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
-
};
/*
* subsystem, followed by a period */
char name[MAX_CFTYPE_NAME];
int private;
- int (*open) (struct inode *inode, struct file *file);
- ssize_t (*read) (struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- char __user *buf, size_t nbytes, loff_t *ppos);
+
+ /*
+ * If non-zero, defines the maximum length of string that can
+ * be passed to write_string; defaults to 64
+ */
+ size_t max_write_len;
+
+ int (*open)(struct inode *inode, struct file *file);
+ ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes, loff_t *ppos);
/*
* 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 *cgrp, struct cftype *cft);
+ u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
/*
* read_s64() is a signed version of read_u64()
*/
- s64 (*read_s64) (struct cgroup *cgrp, struct cftype *cft);
+ s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
/*
* read_map() is used for defining a map of key/value
* pairs. It should call cb->fill(cb, key, value) for each
* entry. The key/value pairs (and their ordering) should not
* change between reboots.
*/
- int (*read_map) (struct cgroup *cont, struct cftype *cft,
- struct cgroup_map_cb *cb);
+ int (*read_map)(struct cgroup *cont, struct cftype *cft,
+ struct cgroup_map_cb *cb);
+ /*
+ * read_seq_string() is used for outputting a simple sequence
+ * using seqfile.
+ */
+ int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
+ struct seq_file *m);
- ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft,
- struct file *file,
- const char __user *buf, size_t nbytes, loff_t *ppos);
+ ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ const char __user *buf, size_t nbytes, loff_t *ppos);
/*
* 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 *cgrp, struct cftype *cft, u64 val);
+ int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
/*
* write_s64() is a signed version of write_u64()
*/
- int (*write_s64) (struct cgroup *cgrp, struct cftype *cft, s64 val);
+ int (*write_s64)(struct cgroup *cgrp, 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 *cgrp, struct cftype *cft,
+ const char *buffer);
+ /*
+ * trigger() callback can be used to get some kick from the
+ * userspace, when the actual string written is not important
+ * at all. The private field can be used to determine the
+ * kick type for multiplexing.
+ */
+ int (*trigger)(struct cgroup *cgrp, unsigned int event);
- int (*release) (struct inode *inode, struct file *file);
+ int (*release)(struct inode *inode, struct file *file);
};
struct cgroup_scanner {
struct cgroup *cgrp);
void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
+
int subsys_id;
int active;
int disabled;
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
- /* Protected by RCU */
- struct cgroupfs_root *root;
+ /*
+ * Protects sibling/children links of cgroups in this
+ * hierarchy, plus protects which hierarchy (or none) the
+ * subsystem is a part of (i.e. root/sibling). To avoid
+ * potential deadlocks, the following operations should not be
+ * undertaken while holding any hierarchy_mutex:
+ *
+ * - allocating memory
+ * - initiating hotplug events
+ */
+ struct mutex hierarchy_mutex;
+ /*
+ * Link to parent, and list entry in parent's children.
+ * Protected by this->hierarchy_mutex and cgroup_lock()
+ */
+ struct cgroupfs_root *root;
struct list_head sibling;
-
- void *private;
};
#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
return task_subsys_state(task, subsys_id)->cgroup;
}
-int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss);
+int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss,
+ char *nodename);
/* A cgroup_iter should be treated as an opaque object */
struct cgroup_iter {
static inline int cgroup_init_early(void) { return 0; }
static inline int cgroup_init(void) { return 0; }
-static inline void cgroup_init_smp(void) {}
static inline void cgroup_fork(struct task_struct *p) {}
static inline void cgroup_fork_callbacks(struct task_struct *p) {}
static inline void cgroup_post_fork(struct task_struct *p) {}
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