1 #ifndef __CGROUP_INTERNAL_H
2 #define __CGROUP_INTERNAL_H
3 
4 #include <linux/cgroup.h>
5 #include <linux/kernfs.h>
6 #include <linux/workqueue.h>
7 #include <linux/list.h>
8 #include <linux/refcount.h>
9 
10 /*
11  * A cgroup can be associated with multiple css_sets as different tasks may
12  * belong to different cgroups on different hierarchies.  In the other
13  * direction, a css_set is naturally associated with multiple cgroups.
14  * This M:N relationship is represented by the following link structure
15  * which exists for each association and allows traversing the associations
16  * from both sides.
17  */
18 struct cgrp_cset_link {
19 	/* the cgroup and css_set this link associates */
20 	struct cgroup		*cgrp;
21 	struct css_set		*cset;
22 
23 	/* list of cgrp_cset_links anchored at cgrp->cset_links */
24 	struct list_head	cset_link;
25 
26 	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
27 	struct list_head	cgrp_link;
28 };
29 
30 /* used to track tasks and csets during migration */
31 struct cgroup_taskset {
32 	/* the src and dst cset list running through cset->mg_node */
33 	struct list_head	src_csets;
34 	struct list_head	dst_csets;
35 
36 	/* the number of tasks in the set */
37 	int			nr_tasks;
38 
39 	/* the subsys currently being processed */
40 	int			ssid;
41 
42 	/*
43 	 * Fields for cgroup_taskset_*() iteration.
44 	 *
45 	 * Before migration is committed, the target migration tasks are on
46 	 * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
47 	 * the csets on ->dst_csets.  ->csets point to either ->src_csets
48 	 * or ->dst_csets depending on whether migration is committed.
49 	 *
50 	 * ->cur_csets and ->cur_task point to the current task position
51 	 * during iteration.
52 	 */
53 	struct list_head	*csets;
54 	struct css_set		*cur_cset;
55 	struct task_struct	*cur_task;
56 };
57 
58 /* migration context also tracks preloading */
59 struct cgroup_mgctx {
60 	/*
61 	 * Preloaded source and destination csets.  Used to guarantee
62 	 * atomic success or failure on actual migration.
63 	 */
64 	struct list_head	preloaded_src_csets;
65 	struct list_head	preloaded_dst_csets;
66 
67 	/* tasks and csets to migrate */
68 	struct cgroup_taskset	tset;
69 
70 	/* subsystems affected by migration */
71 	u16			ss_mask;
72 };
73 
74 #define CGROUP_TASKSET_INIT(tset)						\
75 {										\
76 	.src_csets		= LIST_HEAD_INIT(tset.src_csets),		\
77 	.dst_csets		= LIST_HEAD_INIT(tset.dst_csets),		\
78 	.csets			= &tset.src_csets,				\
79 }
80 
81 #define CGROUP_MGCTX_INIT(name)							\
82 {										\
83 	LIST_HEAD_INIT(name.preloaded_src_csets),				\
84 	LIST_HEAD_INIT(name.preloaded_dst_csets),				\
85 	CGROUP_TASKSET_INIT(name.tset),						\
86 }
87 
88 #define DEFINE_CGROUP_MGCTX(name)						\
89 	struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
90 
91 struct cgroup_sb_opts {
92 	u16 subsys_mask;
93 	unsigned int flags;
94 	char *release_agent;
95 	bool cpuset_clone_children;
96 	char *name;
97 	/* User explicitly requested empty subsystem */
98 	bool none;
99 };
100 
101 extern struct mutex cgroup_mutex;
102 extern spinlock_t css_set_lock;
103 extern struct cgroup_subsys *cgroup_subsys[];
104 extern struct list_head cgroup_roots;
105 extern struct file_system_type cgroup_fs_type;
106 
107 /* iterate across the hierarchies */
108 #define for_each_root(root)						\
109 	list_for_each_entry((root), &cgroup_roots, root_list)
110 
111 /**
112  * for_each_subsys - iterate all enabled cgroup subsystems
113  * @ss: the iteration cursor
114  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
115  */
116 #define for_each_subsys(ss, ssid)					\
117 	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
118 	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
119 
120 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
121 {
122 	return !(cgrp->self.flags & CSS_ONLINE);
123 }
124 
125 static inline bool notify_on_release(const struct cgroup *cgrp)
126 {
127 	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
128 }
129 
130 void put_css_set_locked(struct css_set *cset);
131 
132 static inline void put_css_set(struct css_set *cset)
133 {
134 	unsigned long flags;
135 
136 	/*
137 	 * Ensure that the refcount doesn't hit zero while any readers
138 	 * can see it. Similar to atomic_dec_and_lock(), but for an
139 	 * rwlock
140 	 */
141 	if (refcount_dec_not_one(&cset->refcount))
142 		return;
143 
144 	spin_lock_irqsave(&css_set_lock, flags);
145 	put_css_set_locked(cset);
146 	spin_unlock_irqrestore(&css_set_lock, flags);
147 }
148 
149 /*
150  * refcounted get/put for css_set objects
151  */
152 static inline void get_css_set(struct css_set *cset)
153 {
154 	refcount_inc(&cset->refcount);
155 }
156 
157 bool cgroup_ssid_enabled(int ssid);
158 bool cgroup_on_dfl(const struct cgroup *cgrp);
159 
160 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
161 struct cgroup *task_cgroup_from_root(struct task_struct *task,
162 				     struct cgroup_root *root);
163 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
164 void cgroup_kn_unlock(struct kernfs_node *kn);
165 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
166 			  struct cgroup_namespace *ns);
167 
168 void cgroup_free_root(struct cgroup_root *root);
169 void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
170 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags);
171 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
172 struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
173 			       struct cgroup_root *root, unsigned long magic,
174 			       struct cgroup_namespace *ns);
175 
176 bool cgroup_may_migrate_to(struct cgroup *dst_cgrp);
177 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
178 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
179 			    struct cgroup_mgctx *mgctx);
180 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
181 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
182 		   struct cgroup_mgctx *mgctx);
183 
184 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
185 		       bool threadgroup);
186 ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
187 			     size_t nbytes, loff_t off, bool threadgroup);
188 ssize_t cgroup_procs_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
189 			   loff_t off);
190 
191 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
192 
193 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
194 int cgroup_rmdir(struct kernfs_node *kn);
195 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
196 		     struct kernfs_root *kf_root);
197 
198 int cgroup_task_count(const struct cgroup *cgrp);
199 
200 /*
201  * namespace.c
202  */
203 extern const struct proc_ns_operations cgroupns_operations;
204 
205 /*
206  * cgroup-v1.c
207  */
208 extern struct cftype cgroup1_base_files[];
209 extern const struct file_operations proc_cgroupstats_operations;
210 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
211 
212 bool cgroup1_ssid_disabled(int ssid);
213 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
214 void cgroup1_release_agent(struct work_struct *work);
215 void cgroup1_check_for_release(struct cgroup *cgrp);
216 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
217 			     void *data, unsigned long magic,
218 			     struct cgroup_namespace *ns);
219 
220 #endif /* __CGROUP_INTERNAL_H */
221