cgroup-internal.h

  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_parser.h>
 11
 12#define TRACE_CGROUP_PATH_LEN 1024
 13extern spinlock_t trace_cgroup_path_lock;
 14extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
 15extern void __init enable_debug_cgroup(void);
 16
 17/*
 18 * cgroup_path() takes a spin lock. It is good practice not to take
 19 * spin locks within trace point handlers, as they are mostly hidden
 20 * from normal view. As cgroup_path() can take the kernfs_rename_lock
 21 * spin lock, it is best to not call that function from the trace event
 22 * handler.
 23 *
 24 * Note: trace_cgroup_##type##_enabled() is a static branch that will only
 25 *       be set when the trace event is enabled.
 26 */
 27#define TRACE_CGROUP_PATH(type, cgrp, ...)				\
 28	do {								\
 29		if (trace_cgroup_##type##_enabled()) {			\
 30			unsigned long flags;				\
 31			spin_lock_irqsave(&trace_cgroup_path_lock,	\
 32					  flags);			\
 33			cgroup_path(cgrp, trace_cgroup_path,		\
 34				    TRACE_CGROUP_PATH_LEN);		\
 35			trace_cgroup_##type(cgrp, trace_cgroup_path,	\
 36					    ##__VA_ARGS__);		\
 37			spin_unlock_irqrestore(&trace_cgroup_path_lock, \
 38					       flags);			\
 39		}							\
 40	} while (0)
 41
 42/*
 43 * The cgroup filesystem superblock creation/mount context.
 44 */
 45struct cgroup_fs_context {
 46	struct kernfs_fs_context kfc;
 47	struct cgroup_root	*root;
 48	struct cgroup_namespace	*ns;
 49	unsigned int	flags;			/* CGRP_ROOT_* flags */
 50
 51	/* cgroup1 bits */
 52	bool		cpuset_clone_children;
 53	bool		none;			/* User explicitly requested empty subsystem */
 54	bool		all_ss;			/* Seen 'all' option */
 55	u16		subsys_mask;		/* Selected subsystems */
 56	char		*name;			/* Hierarchy name */
 57	char		*release_agent;		/* Path for release notifications */
 58};
 59
 60static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
 61{
 62	struct kernfs_fs_context *kfc = fc->fs_private;
 63
 64	return container_of(kfc, struct cgroup_fs_context, kfc);
 65}
 66
 67struct cgroup_pidlist;
 68
 69struct cgroup_file_ctx {
 70	struct cgroup_namespace	*ns;
 71
 72	struct {
 73		void			*trigger;
 74	} psi;
 75
 76	struct {
 77		bool			started;
 78		struct css_task_iter	iter;
 79	} procs;
 80
 81	struct {
 82		struct cgroup_pidlist	*pidlist;
 83	} procs1;
 84
 85	struct cgroup_of_peak peak;
 86};
 87
 88/*
 89 * A cgroup can be associated with multiple css_sets as different tasks may
 90 * belong to different cgroups on different hierarchies.  In the other
 91 * direction, a css_set is naturally associated with multiple cgroups.
 92 * This M:N relationship is represented by the following link structure
 93 * which exists for each association and allows traversing the associations
 94 * from both sides.
 95 */
 96struct cgrp_cset_link {
 97	/* the cgroup and css_set this link associates */
 98	struct cgroup		*cgrp;
 99	struct css_set		*cset;
100
101	/* list of cgrp_cset_links anchored at cgrp->cset_links */
102	struct list_head	cset_link;
103
104	/* list of cgrp_cset_links anchored at css_set->cgrp_links */
105	struct list_head	cgrp_link;
106};
107
108/* used to track tasks and csets during migration */
109struct cgroup_taskset {
110	/* the src and dst cset list running through cset->mg_node */
111	struct list_head	src_csets;
112	struct list_head	dst_csets;
113
114	/* the number of tasks in the set */
115	int			nr_tasks;
116
117	/* the subsys currently being processed */
118	int			ssid;
119
120	/*
121	 * Fields for cgroup_taskset_*() iteration.
122	 *
123	 * Before migration is committed, the target migration tasks are on
124	 * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
125	 * the csets on ->dst_csets.  ->csets point to either ->src_csets
126	 * or ->dst_csets depending on whether migration is committed.
127	 *
128	 * ->cur_csets and ->cur_task point to the current task position
129	 * during iteration.
130	 */
131	struct list_head	*csets;
132	struct css_set		*cur_cset;
133	struct task_struct	*cur_task;
134};
135
136/* migration context also tracks preloading */
137struct cgroup_mgctx {
138	/*
139	 * Preloaded source and destination csets.  Used to guarantee
140	 * atomic success or failure on actual migration.
141	 */
142	struct list_head	preloaded_src_csets;
143	struct list_head	preloaded_dst_csets;
144
145	/* tasks and csets to migrate */
146	struct cgroup_taskset	tset;
147
148	/* subsystems affected by migration */
149	u16			ss_mask;
150};
151
152#define CGROUP_TASKSET_INIT(tset)						\
153{										\
154	.src_csets		= LIST_HEAD_INIT(tset.src_csets),		\
155	.dst_csets		= LIST_HEAD_INIT(tset.dst_csets),		\
156	.csets			= &tset.src_csets,				\
157}
158
159#define CGROUP_MGCTX_INIT(name)							\
160{										\
161	LIST_HEAD_INIT(name.preloaded_src_csets),				\
162	LIST_HEAD_INIT(name.preloaded_dst_csets),				\
163	CGROUP_TASKSET_INIT(name.tset),						\
164}
165
166#define DEFINE_CGROUP_MGCTX(name)						\
167	struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
168
169extern struct cgroup_subsys *cgroup_subsys[];
170extern struct list_head cgroup_roots;
171extern bool cgrp_dfl_visible;
172
173/* iterate across the hierarchies */
174#define for_each_root(root)						\
175	list_for_each_entry_rcu((root), &cgroup_roots, root_list,	\
176				lockdep_is_held(&cgroup_mutex))
177
178/**
179 * for_each_subsys - iterate all enabled cgroup subsystems
180 * @ss: the iteration cursor
181 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
182 */
183#define for_each_subsys(ss, ssid)					\
184	for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&		\
185	     (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
186
187static inline bool cgroup_is_dead(const struct cgroup *cgrp)
188{
189	return !(cgrp->self.flags & CSS_ONLINE);
190}
191
192static inline bool notify_on_release(const struct cgroup *cgrp)
193{
194	return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
195}
196
197void put_css_set_locked(struct css_set *cset);
198
199static inline void put_css_set(struct css_set *cset)
200{
201	unsigned long flags;
202
203	/*
204	 * Ensure that the refcount doesn't hit zero while any readers
205	 * can see it. Similar to atomic_dec_and_lock(), but for an
206	 * rwlock
207	 */
208	if (refcount_dec_not_one(&cset->refcount))
209		return;
210
211	spin_lock_irqsave(&css_set_lock, flags);
212	put_css_set_locked(cset);
213	spin_unlock_irqrestore(&css_set_lock, flags);
214}
215
216/*
217 * refcounted get/put for css_set objects
218 */
219static inline void get_css_set(struct css_set *cset)
220{
221	refcount_inc(&cset->refcount);
222}
223
224bool cgroup_ssid_enabled(int ssid);
225bool cgroup_on_dfl(const struct cgroup *cgrp);
226
227struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
228struct cgroup *task_cgroup_from_root(struct task_struct *task,
229				     struct cgroup_root *root);
230struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
231void cgroup_kn_unlock(struct kernfs_node *kn);
232int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
233			  struct cgroup_namespace *ns);
234
235void cgroup_favor_dynmods(struct cgroup_root *root, bool favor);
236void cgroup_free_root(struct cgroup_root *root);
237void init_cgroup_root(struct cgroup_fs_context *ctx);
238int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
239int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
240int cgroup_do_get_tree(struct fs_context *fc);
241
242int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
243void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
244void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
245			    struct cgroup_mgctx *mgctx);
246int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
247int cgroup_migrate(struct task_struct *leader, bool threadgroup,
248		   struct cgroup_mgctx *mgctx);
249
250int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
251		       bool threadgroup);
252void cgroup_attach_lock(enum cgroup_attach_lock_mode lock_mode,
253			struct task_struct *tsk);
254void cgroup_attach_unlock(enum cgroup_attach_lock_mode lock_mode,
255			  struct task_struct *tsk);
256struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
257					     enum cgroup_attach_lock_mode *lock_mode)
258	__acquires(&cgroup_threadgroup_rwsem);
259void cgroup_procs_write_finish(struct task_struct *task,
260			       enum cgroup_attach_lock_mode lock_mode)
261	__releases(&cgroup_threadgroup_rwsem);
262
263void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
264
265int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
266int cgroup_rmdir(struct kernfs_node *kn);
267int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
268		     struct kernfs_root *kf_root);
269
270int __cgroup_task_count(const struct cgroup *cgrp);
271int cgroup_task_count(const struct cgroup *cgrp);
272
273/*
274 * rstat.c
275 */
276int css_rstat_init(struct cgroup_subsys_state *css);
277void css_rstat_exit(struct cgroup_subsys_state *css);
278int ss_rstat_init(struct cgroup_subsys *ss);
279void cgroup_base_stat_cputime_show(struct seq_file *seq);
280
281/*
282 * namespace.c
283 */
284extern const struct proc_ns_operations cgroupns_operations;
285
286/*
287 * cgroup-v1.c
288 */
289extern struct cftype cgroup1_base_files[];
290extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
291extern const struct fs_parameter_spec cgroup1_fs_parameters[];
292
293int proc_cgroupstats_show(struct seq_file *m, void *v);
294bool cgroup1_ssid_disabled(int ssid);
295void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
296void cgroup1_release_agent(struct work_struct *work);
297void cgroup1_check_for_release(struct cgroup *cgrp);
298int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
299int cgroup1_get_tree(struct fs_context *fc);
300int cgroup1_reconfigure(struct fs_context *ctx);
301
302#endif /* __CGROUP_INTERNAL_H */