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 #define TRACE_CGROUP_PATH_LEN 1024
12 extern spinlock_t trace_cgroup_path_lock;
13 extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
14
15 /*
16 * cgroup_path() takes a spin lock. It is good practice not to take
17 * spin locks within trace point handlers, as they are mostly hidden
18 * from normal view. As cgroup_path() can take the kernfs_rename_lock
19 * spin lock, it is best to not call that function from the trace event
20 * handler.
21 *
22 * Note: trace_cgroup_##type##_enabled() is a static branch that will only
23 * be set when the trace event is enabled.
24 */
25 #define TRACE_CGROUP_PATH(type, cgrp, ...) \
26 do { \
27 if (trace_cgroup_##type##_enabled()) { \
28 spin_lock(&trace_cgroup_path_lock); \
29 cgroup_path(cgrp, trace_cgroup_path, \
30 TRACE_CGROUP_PATH_LEN); \
31 trace_cgroup_##type(cgrp, trace_cgroup_path, \
32 ##__VA_ARGS__); \
33 spin_unlock(&trace_cgroup_path_lock); \
34 } \
35 } while (0)
36
37 /*
38 * A cgroup can be associated with multiple css_sets as different tasks may
39 * belong to different cgroups on different hierarchies. In the other
40 * direction, a css_set is naturally associated with multiple cgroups.
41 * This M:N relationship is represented by the following link structure
42 * which exists for each association and allows traversing the associations
43 * from both sides.
44 */
45 struct cgrp_cset_link {
46 /* the cgroup and css_set this link associates */
47 struct cgroup *cgrp;
48 struct css_set *cset;
49
50 /* list of cgrp_cset_links anchored at cgrp->cset_links */
51 struct list_head cset_link;
52
53 /* list of cgrp_cset_links anchored at css_set->cgrp_links */
54 struct list_head cgrp_link;
55 };
56
57 /* used to track tasks and csets during migration */
58 struct cgroup_taskset {
59 /* the src and dst cset list running through cset->mg_node */
60 struct list_head src_csets;
61 struct list_head dst_csets;
62
63 /* the number of tasks in the set */
64 int nr_tasks;
65
66 /* the subsys currently being processed */
67 int ssid;
68
69 /*
70 * Fields for cgroup_taskset_*() iteration.
71 *
72 * Before migration is committed, the target migration tasks are on
73 * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
74 * the csets on ->dst_csets. ->csets point to either ->src_csets
75 * or ->dst_csets depending on whether migration is committed.
76 *
77 * ->cur_csets and ->cur_task point to the current task position
78 * during iteration.
79 */
80 struct list_head *csets;
81 struct css_set *cur_cset;
82 struct task_struct *cur_task;
83 };
84
85 /* migration context also tracks preloading */
86 struct cgroup_mgctx {
87 /*
88 * Preloaded source and destination csets. Used to guarantee
89 * atomic success or failure on actual migration.
90 */
91 struct list_head preloaded_src_csets;
92 struct list_head preloaded_dst_csets;
93
94 /* tasks and csets to migrate */
95 struct cgroup_taskset tset;
96
97 /* subsystems affected by migration */
98 u16 ss_mask;
99 };
100
101 #define CGROUP_TASKSET_INIT(tset) \
102 { \
103 .src_csets = LIST_HEAD_INIT(tset.src_csets), \
104 .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
105 .csets = &tset.src_csets, \
106 }
107
108 #define CGROUP_MGCTX_INIT(name) \
109 { \
110 LIST_HEAD_INIT(name.preloaded_src_csets), \
111 LIST_HEAD_INIT(name.preloaded_dst_csets), \
112 CGROUP_TASKSET_INIT(name.tset), \
113 }
114
115 #define DEFINE_CGROUP_MGCTX(name) \
116 struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
117
118 struct cgroup_sb_opts {
119 u16 subsys_mask;
120 unsigned int flags;
121 char *release_agent;
122 bool cpuset_clone_children;
123 char *name;
124 /* User explicitly requested empty subsystem */
125 bool none;
126 };
127
128 extern struct mutex cgroup_mutex;
129 extern spinlock_t css_set_lock;
130 extern struct cgroup_subsys *cgroup_subsys[];
131 extern struct list_head cgroup_roots;
132 extern struct file_system_type cgroup_fs_type;
133
134 /* iterate across the hierarchies */
135 #define for_each_root(root) \
136 list_for_each_entry((root), &cgroup_roots, root_list)
137
138 /**
139 * for_each_subsys - iterate all enabled cgroup subsystems
140 * @ss: the iteration cursor
141 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
142 */
143 #define for_each_subsys(ss, ssid) \
144 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
145 (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
146
cgroup_is_dead(const struct cgroup * cgrp)147 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
148 {
149 return !(cgrp->self.flags & CSS_ONLINE);
150 }
151
notify_on_release(const struct cgroup * cgrp)152 static inline bool notify_on_release(const struct cgroup *cgrp)
153 {
154 return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
155 }
156
157 void put_css_set_locked(struct css_set *cset);
158
put_css_set(struct css_set * cset)159 static inline void put_css_set(struct css_set *cset)
160 {
161 unsigned long flags;
162
163 /*
164 * Ensure that the refcount doesn't hit zero while any readers
165 * can see it. Similar to atomic_dec_and_lock(), but for an
166 * rwlock
167 */
168 if (refcount_dec_not_one(&cset->refcount))
169 return;
170
171 spin_lock_irqsave(&css_set_lock, flags);
172 put_css_set_locked(cset);
173 spin_unlock_irqrestore(&css_set_lock, flags);
174 }
175
176 /*
177 * refcounted get/put for css_set objects
178 */
get_css_set(struct css_set * cset)179 static inline void get_css_set(struct css_set *cset)
180 {
181 refcount_inc(&cset->refcount);
182 }
183
184 bool cgroup_ssid_enabled(int ssid);
185 bool cgroup_on_dfl(const struct cgroup *cgrp);
186 bool cgroup_is_thread_root(struct cgroup *cgrp);
187 bool cgroup_is_threaded(struct cgroup *cgrp);
188
189 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
190 struct cgroup *task_cgroup_from_root(struct task_struct *task,
191 struct cgroup_root *root);
192 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
193 void cgroup_kn_unlock(struct kernfs_node *kn);
194 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
195 struct cgroup_namespace *ns);
196
197 void cgroup_free_root(struct cgroup_root *root);
198 void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
199 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags);
200 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
201 struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
202 struct cgroup_root *root, unsigned long magic,
203 struct cgroup_namespace *ns);
204
205 int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
206 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
207 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
208 struct cgroup_mgctx *mgctx);
209 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
210 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
211 struct cgroup_mgctx *mgctx);
212
213 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
214 bool threadgroup);
215 struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
216 __acquires(&cgroup_threadgroup_rwsem);
217 void cgroup_procs_write_finish(struct task_struct *task)
218 __releases(&cgroup_threadgroup_rwsem);
219
220 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
221
222 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
223 int cgroup_rmdir(struct kernfs_node *kn);
224 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
225 struct kernfs_root *kf_root);
226
227 int cgroup_task_count(const struct cgroup *cgrp);
228
229 /*
230 * rstat.c
231 */
232 int cgroup_rstat_init(struct cgroup *cgrp);
233 void cgroup_rstat_exit(struct cgroup *cgrp);
234 void cgroup_rstat_boot(void);
235 void cgroup_base_stat_cputime_show(struct seq_file *seq);
236
237 /*
238 * namespace.c
239 */
240 extern const struct proc_ns_operations cgroupns_operations;
241
242 /*
243 * cgroup-v1.c
244 */
245 extern struct cftype cgroup1_base_files[];
246 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
247
248 int proc_cgroupstats_show(struct seq_file *m, void *v);
249 bool cgroup1_ssid_disabled(int ssid);
250 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
251 void cgroup1_release_agent(struct work_struct *work);
252 void cgroup1_check_for_release(struct cgroup *cgrp);
253 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
254 void *data, unsigned long magic,
255 struct cgroup_namespace *ns);
256
257 #endif /* __CGROUP_INTERNAL_H */
258
