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 #include <linux/fs_context.h>
11
12 #define TRACE_CGROUP_PATH_LEN 1024
13 extern spinlock_t trace_cgroup_path_lock;
14 extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
15 extern bool cgroup_debug;
16 extern void __init enable_debug_cgroup(void);
17
18 /*
19 * cgroup_path() takes a spin lock. It is good practice not to take
20 * spin locks within trace point handlers, as they are mostly hidden
21 * from normal view. As cgroup_path() can take the kernfs_rename_lock
22 * spin lock, it is best to not call that function from the trace event
23 * handler.
24 *
25 * Note: trace_cgroup_##type##_enabled() is a static branch that will only
26 * be set when the trace event is enabled.
27 */
28 #define TRACE_CGROUP_PATH(type, cgrp, ...) \
29 do { \
30 if (trace_cgroup_##type##_enabled()) { \
31 unsigned long flags; \
32 spin_lock_irqsave(&trace_cgroup_path_lock, \
33 flags); \
34 cgroup_path(cgrp, trace_cgroup_path, \
35 TRACE_CGROUP_PATH_LEN); \
36 trace_cgroup_##type(cgrp, trace_cgroup_path, \
37 ##__VA_ARGS__); \
38 spin_unlock_irqrestore(&trace_cgroup_path_lock, \
39 flags); \
40 } \
41 } while (0)
42
43 /*
44 * The cgroup filesystem superblock creation/mount context.
45 */
46 struct cgroup_fs_context {
47 struct kernfs_fs_context kfc;
48 struct cgroup_root *root;
49 struct cgroup_namespace *ns;
50 unsigned int flags; /* CGRP_ROOT_* flags */
51
52 /* cgroup1 bits */
53 bool cpuset_clone_children;
54 bool none; /* User explicitly requested empty subsystem */
55 bool all_ss; /* Seen 'all' option */
56 u16 subsys_mask; /* Selected subsystems */
57 char *name; /* Hierarchy name */
58 char *release_agent; /* Path for release notifications */
59 };
60
cgroup_fc2context(struct fs_context * fc)61 static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
62 {
63 struct kernfs_fs_context *kfc = fc->fs_private;
64
65 return container_of(kfc, struct cgroup_fs_context, kfc);
66 }
67
68 /*
69 * A cgroup can be associated with multiple css_sets as different tasks may
70 * belong to different cgroups on different hierarchies. In the other
71 * direction, a css_set is naturally associated with multiple cgroups.
72 * This M:N relationship is represented by the following link structure
73 * which exists for each association and allows traversing the associations
74 * from both sides.
75 */
76 struct cgrp_cset_link {
77 /* the cgroup and css_set this link associates */
78 struct cgroup *cgrp;
79 struct css_set *cset;
80
81 /* list of cgrp_cset_links anchored at cgrp->cset_links */
82 struct list_head cset_link;
83
84 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
85 struct list_head cgrp_link;
86 };
87
88 /* used to track tasks and csets during migration */
89 struct cgroup_taskset {
90 /* the src and dst cset list running through cset->mg_node */
91 struct list_head src_csets;
92 struct list_head dst_csets;
93
94 /* the number of tasks in the set */
95 int nr_tasks;
96
97 /* the subsys currently being processed */
98 int ssid;
99
100 /*
101 * Fields for cgroup_taskset_*() iteration.
102 *
103 * Before migration is committed, the target migration tasks are on
104 * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
105 * the csets on ->dst_csets. ->csets point to either ->src_csets
106 * or ->dst_csets depending on whether migration is committed.
107 *
108 * ->cur_csets and ->cur_task point to the current task position
109 * during iteration.
110 */
111 struct list_head *csets;
112 struct css_set *cur_cset;
113 struct task_struct *cur_task;
114 };
115
116 /* migration context also tracks preloading */
117 struct cgroup_mgctx {
118 /*
119 * Preloaded source and destination csets. Used to guarantee
120 * atomic success or failure on actual migration.
121 */
122 struct list_head preloaded_src_csets;
123 struct list_head preloaded_dst_csets;
124
125 /* tasks and csets to migrate */
126 struct cgroup_taskset tset;
127
128 /* subsystems affected by migration */
129 u16 ss_mask;
130 };
131
132 #define CGROUP_TASKSET_INIT(tset) \
133 { \
134 .src_csets = LIST_HEAD_INIT(tset.src_csets), \
135 .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
136 .csets = &tset.src_csets, \
137 }
138
139 #define CGROUP_MGCTX_INIT(name) \
140 { \
141 LIST_HEAD_INIT(name.preloaded_src_csets), \
142 LIST_HEAD_INIT(name.preloaded_dst_csets), \
143 CGROUP_TASKSET_INIT(name.tset), \
144 }
145
146 #define DEFINE_CGROUP_MGCTX(name) \
147 struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
148
149 extern struct mutex cgroup_mutex;
150 extern spinlock_t css_set_lock;
151 extern struct cgroup_subsys *cgroup_subsys[];
152 extern struct list_head cgroup_roots;
153 extern struct file_system_type cgroup_fs_type;
154
155 /* iterate across the hierarchies */
156 #define for_each_root(root) \
157 list_for_each_entry((root), &cgroup_roots, root_list)
158
159 /**
160 * for_each_subsys - iterate all enabled cgroup subsystems
161 * @ss: the iteration cursor
162 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
163 */
164 #define for_each_subsys(ss, ssid) \
165 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
166 (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
167
cgroup_is_dead(const struct cgroup * cgrp)168 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
169 {
170 return !(cgrp->self.flags & CSS_ONLINE);
171 }
172
notify_on_release(const struct cgroup * cgrp)173 static inline bool notify_on_release(const struct cgroup *cgrp)
174 {
175 return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
176 }
177
178 void put_css_set_locked(struct css_set *cset);
179
put_css_set(struct css_set * cset)180 static inline void put_css_set(struct css_set *cset)
181 {
182 unsigned long flags;
183
184 /*
185 * Ensure that the refcount doesn't hit zero while any readers
186 * can see it. Similar to atomic_dec_and_lock(), but for an
187 * rwlock
188 */
189 if (refcount_dec_not_one(&cset->refcount))
190 return;
191
192 spin_lock_irqsave(&css_set_lock, flags);
193 put_css_set_locked(cset);
194 spin_unlock_irqrestore(&css_set_lock, flags);
195 }
196
197 /*
198 * refcounted get/put for css_set objects
199 */
get_css_set(struct css_set * cset)200 static inline void get_css_set(struct css_set *cset)
201 {
202 refcount_inc(&cset->refcount);
203 }
204
205 bool cgroup_ssid_enabled(int ssid);
206 bool cgroup_on_dfl(const struct cgroup *cgrp);
207 bool cgroup_is_thread_root(struct cgroup *cgrp);
208 bool cgroup_is_threaded(struct cgroup *cgrp);
209
210 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
211 struct cgroup *task_cgroup_from_root(struct task_struct *task,
212 struct cgroup_root *root);
213 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
214 void cgroup_kn_unlock(struct kernfs_node *kn);
215 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
216 struct cgroup_namespace *ns);
217
218 void cgroup_free_root(struct cgroup_root *root);
219 void init_cgroup_root(struct cgroup_fs_context *ctx);
220 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
221 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
222 int cgroup_do_get_tree(struct fs_context *fc);
223
224 int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
225 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
226 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
227 struct cgroup_mgctx *mgctx);
228 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
229 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
230 struct cgroup_mgctx *mgctx);
231
232 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
233 bool threadgroup);
234 struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
235 __acquires(&cgroup_threadgroup_rwsem);
236 void cgroup_procs_write_finish(struct task_struct *task)
237 __releases(&cgroup_threadgroup_rwsem);
238
239 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
240
241 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
242 int cgroup_rmdir(struct kernfs_node *kn);
243 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
244 struct kernfs_root *kf_root);
245
246 int __cgroup_task_count(const struct cgroup *cgrp);
247 int cgroup_task_count(const struct cgroup *cgrp);
248
249 /*
250 * rstat.c
251 */
252 int cgroup_rstat_init(struct cgroup *cgrp);
253 void cgroup_rstat_exit(struct cgroup *cgrp);
254 void cgroup_rstat_boot(void);
255 void cgroup_base_stat_cputime_show(struct seq_file *seq);
256
257 /*
258 * namespace.c
259 */
260 extern const struct proc_ns_operations cgroupns_operations;
261
262 /*
263 * cgroup-v1.c
264 */
265 extern struct cftype cgroup1_base_files[];
266 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
267 extern const struct fs_parameter_description cgroup1_fs_parameters;
268
269 int proc_cgroupstats_show(struct seq_file *m, void *v);
270 bool cgroup1_ssid_disabled(int ssid);
271 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
272 void cgroup1_release_agent(struct work_struct *work);
273 void cgroup1_check_for_release(struct cgroup *cgrp);
274 int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
275 int cgroup1_get_tree(struct fs_context *fc);
276 int cgroup1_reconfigure(struct fs_context *ctx);
277
278 #endif /* __CGROUP_INTERNAL_H */
279
