1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __CGROUP_INTERNAL_H
3 #define __CGROUP_INTERNAL_H
4 
5 #include <linux/cgroup.h>
6 #include <linux/kernfs.h>
7 #include <linux/workqueue.h>
8 #include <linux/list.h>
9 #include <linux/refcount.h>
10 
11 /*
12  * A cgroup can be associated with multiple css_sets as different tasks may
13  * belong to different cgroups on different hierarchies.  In the other
14  * direction, a css_set is naturally associated with multiple cgroups.
15  * This M:N relationship is represented by the following link structure
16  * which exists for each association and allows traversing the associations
17  * from both sides.
18  */
19 struct cgrp_cset_link {
20 	/* the cgroup and css_set this link associates */
21 	struct cgroup		*cgrp;
22 	struct css_set		*cset;
23 
24 	/* list of cgrp_cset_links anchored at cgrp->cset_links */
25 	struct list_head	cset_link;
26 
27 	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
28 	struct list_head	cgrp_link;
29 };
30 
31 /* used to track tasks and csets during migration */
32 struct cgroup_taskset {
33 	/* the src and dst cset list running through cset->mg_node */
34 	struct list_head	src_csets;
35 	struct list_head	dst_csets;
36 
37 	/* the number of tasks in the set */
38 	int			nr_tasks;
39 
40 	/* the subsys currently being processed */
41 	int			ssid;
42 
43 	/*
44 	 * Fields for cgroup_taskset_*() iteration.
45 	 *
46 	 * Before migration is committed, the target migration tasks are on
47 	 * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
48 	 * the csets on ->dst_csets.  ->csets point to either ->src_csets
49 	 * or ->dst_csets depending on whether migration is committed.
50 	 *
51 	 * ->cur_csets and ->cur_task point to the current task position
52 	 * during iteration.
53 	 */
54 	struct list_head	*csets;
55 	struct css_set		*cur_cset;
56 	struct task_struct	*cur_task;
57 };
58 
59 /* migration context also tracks preloading */
60 struct cgroup_mgctx {
61 	/*
62 	 * Preloaded source and destination csets.  Used to guarantee
63 	 * atomic success or failure on actual migration.
64 	 */
65 	struct list_head	preloaded_src_csets;
66 	struct list_head	preloaded_dst_csets;
67 
68 	/* tasks and csets to migrate */
69 	struct cgroup_taskset	tset;
70 
71 	/* subsystems affected by migration */
72 	u16			ss_mask;
73 };
74 
75 #define CGROUP_TASKSET_INIT(tset)						\
76 {										\
77 	.src_csets		= LIST_HEAD_INIT(tset.src_csets),		\
78 	.dst_csets		= LIST_HEAD_INIT(tset.dst_csets),		\
79 	.csets			= &tset.src_csets,				\
80 }
81 
82 #define CGROUP_MGCTX_INIT(name)							\
83 {										\
84 	LIST_HEAD_INIT(name.preloaded_src_csets),				\
85 	LIST_HEAD_INIT(name.preloaded_dst_csets),				\
86 	CGROUP_TASKSET_INIT(name.tset),						\
87 }
88 
89 #define DEFINE_CGROUP_MGCTX(name)						\
90 	struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
91 
92 struct cgroup_sb_opts {
93 	u16 subsys_mask;
94 	unsigned int flags;
95 	char *release_agent;
96 	bool cpuset_clone_children;
97 	char *name;
98 	/* User explicitly requested empty subsystem */
99 	bool none;
100 };
101 
102 extern struct mutex cgroup_mutex;
103 extern spinlock_t css_set_lock;
104 extern struct cgroup_subsys *cgroup_subsys[];
105 extern struct list_head cgroup_roots;
106 extern struct file_system_type cgroup_fs_type;
107 
108 /* iterate across the hierarchies */
109 #define for_each_root(root)						\
110 	list_for_each_entry((root), &cgroup_roots, root_list)
111 
112 /**
113  * for_each_subsys - iterate all enabled cgroup subsystems
114  * @ss: the iteration cursor
115  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
116  */
117 #define for_each_subsys(ss, ssid)					\
118 	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
119 	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
120 
121 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
122 {
123 	return !(cgrp->self.flags & CSS_ONLINE);
124 }
125 
126 static inline bool notify_on_release(const struct cgroup *cgrp)
127 {
128 	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
129 }
130 
131 void put_css_set_locked(struct css_set *cset);
132 
133 static inline void put_css_set(struct css_set *cset)
134 {
135 	unsigned long flags;
136 
137 	/*
138 	 * Ensure that the refcount doesn't hit zero while any readers
139 	 * can see it. Similar to atomic_dec_and_lock(), but for an
140 	 * rwlock
141 	 */
142 	if (refcount_dec_not_one(&cset->refcount))
143 		return;
144 
145 	spin_lock_irqsave(&css_set_lock, flags);
146 	put_css_set_locked(cset);
147 	spin_unlock_irqrestore(&css_set_lock, flags);
148 }
149 
150 /*
151  * refcounted get/put for css_set objects
152  */
153 static inline void get_css_set(struct css_set *cset)
154 {
155 	refcount_inc(&cset->refcount);
156 }
157 
158 bool cgroup_ssid_enabled(int ssid);
159 bool cgroup_on_dfl(const struct cgroup *cgrp);
160 bool cgroup_is_thread_root(struct cgroup *cgrp);
161 bool cgroup_is_threaded(struct cgroup *cgrp);
162 
163 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
164 struct cgroup *task_cgroup_from_root(struct task_struct *task,
165 				     struct cgroup_root *root);
166 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
167 void cgroup_kn_unlock(struct kernfs_node *kn);
168 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
169 			  struct cgroup_namespace *ns);
170 
171 void cgroup_free_root(struct cgroup_root *root);
172 void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
173 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags);
174 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
175 struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
176 			       struct cgroup_root *root, unsigned long magic,
177 			       struct cgroup_namespace *ns);
178 
179 int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
180 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
181 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
182 			    struct cgroup_mgctx *mgctx);
183 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
184 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
185 		   struct cgroup_mgctx *mgctx);
186 
187 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
188 		       bool threadgroup);
189 struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
190 	__acquires(&cgroup_threadgroup_rwsem);
191 void cgroup_procs_write_finish(struct task_struct *task)
192 	__releases(&cgroup_threadgroup_rwsem);
193 
194 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
195 
196 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
197 int cgroup_rmdir(struct kernfs_node *kn);
198 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
199 		     struct kernfs_root *kf_root);
200 
201 int cgroup_task_count(const struct cgroup *cgrp);
202 
203 /*
204  * stat.c
205  */
206 void cgroup_stat_flush(struct cgroup *cgrp);
207 int cgroup_stat_init(struct cgroup *cgrp);
208 void cgroup_stat_exit(struct cgroup *cgrp);
209 void cgroup_stat_show_cputime(struct seq_file *seq);
210 void cgroup_stat_boot(void);
211 
212 /*
213  * namespace.c
214  */
215 extern const struct proc_ns_operations cgroupns_operations;
216 
217 /*
218  * cgroup-v1.c
219  */
220 extern struct cftype cgroup1_base_files[];
221 extern const struct file_operations proc_cgroupstats_operations;
222 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
223 
224 bool cgroup1_ssid_disabled(int ssid);
225 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
226 void cgroup1_release_agent(struct work_struct *work);
227 void cgroup1_check_for_release(struct cgroup *cgrp);
228 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
229 			     void *data, unsigned long magic,
230 			     struct cgroup_namespace *ns);
231 
232 #endif /* __CGROUP_INTERNAL_H */
233