kernel/cgroup/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
  13 extern spinlock_t trace_cgroup_path_lock;
  14 extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
  15 extern 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  */
  45 struct 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
  60 static 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
  67 struct cgroup_pidlist;
  68
  69 struct 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  */
  96 struct 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 */
 109 struct 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 */
 137 struct 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
 169 extern struct cgroup_subsys *cgroup_subsys[];
 170 extern struct list_head cgroup_roots;
 171
 172 /* iterate across the hierarchies */
 173 #define for_each_root(root)                                             \
 174         list_for_each_entry_rcu((root), &cgroup_roots, root_list,       \
 175                                 lockdep_is_held(&cgroup_mutex))
 176
 177 /**
 178  * for_each_subsys - iterate all enabled cgroup subsystems
 179  * @ss: the iteration cursor
 180  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
 181  */
 182 #define for_each_subsys(ss, ssid)                                       \
 183         for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&                \
 184              (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
 185
 186 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 187 {
 188         return !(cgrp->self.flags & CSS_ONLINE);
 189 }
 190
 191 static inline bool notify_on_release(const struct cgroup *cgrp)
 192 {
 193         return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 194 }
 195
 196 void put_css_set_locked(struct css_set *cset);
 197
 198 static inline void put_css_set(struct css_set *cset)
 199 {
 200         unsigned long flags;
 201
 202         /*
 203          * Ensure that the refcount doesn't hit zero while any readers
 204          * can see it. Similar to atomic_dec_and_lock(), but for an
 205          * rwlock
 206          */
 207         if (refcount_dec_not_one(&cset->refcount))
 208                 return;
 209
 210         spin_lock_irqsave(&css_set_lock, flags);
 211         put_css_set_locked(cset);
 212         spin_unlock_irqrestore(&css_set_lock, flags);
 213 }
 214
 215 /*
 216  * refcounted get/put for css_set objects
 217  */
 218 static inline void get_css_set(struct css_set *cset)
 219 {
 220         refcount_inc(&cset->refcount);
 221 }
 222
 223 bool cgroup_ssid_enabled(int ssid);
 224 bool cgroup_on_dfl(const struct cgroup *cgrp);
 225
 226 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
 227 struct cgroup *task_cgroup_from_root(struct task_struct *task,
 228                                      struct cgroup_root *root);
 229 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
 230 void cgroup_kn_unlock(struct kernfs_node *kn);
 231 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
 232                           struct cgroup_namespace *ns);
 233
 234 void cgroup_favor_dynmods(struct cgroup_root *root, bool favor);
 235 void cgroup_free_root(struct cgroup_root *root);
 236 void init_cgroup_root(struct cgroup_fs_context *ctx);
 237 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
 238 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
 239 int cgroup_do_get_tree(struct fs_context *fc);
 240
 241 int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
 242 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
 243 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
 244                             struct cgroup_mgctx *mgctx);
 245 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
 246 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
 247                    struct cgroup_mgctx *mgctx);
 248
 249 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
 250                        bool threadgroup);
 251 void cgroup_attach_lock(bool lock_threadgroup);
 252 void cgroup_attach_unlock(bool lock_threadgroup);
 253 struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
 254                                              bool *locked)
 255         __acquires(&cgroup_threadgroup_rwsem);
 256 void cgroup_procs_write_finish(struct task_struct *task, bool locked)
 257         __releases(&cgroup_threadgroup_rwsem);
 258
 259 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 260
 261 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
 262 int cgroup_rmdir(struct kernfs_node *kn);
 263 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 264                      struct kernfs_root *kf_root);
 265
 266 int __cgroup_task_count(const struct cgroup *cgrp);
 267 int cgroup_task_count(const struct cgroup *cgrp);
 268
 269 /*
 270  * rstat.c
 271  */
 272 int cgroup_rstat_init(struct cgroup *cgrp);
 273 void cgroup_rstat_exit(struct cgroup *cgrp);
 274 void cgroup_rstat_boot(void);
 275 void cgroup_base_stat_cputime_show(struct seq_file *seq);
 276
 277 /*
 278  * namespace.c
 279  */
 280 extern const struct proc_ns_operations cgroupns_operations;
 281
 282 /*
 283  * cgroup-v1.c
 284  */
 285 extern struct cftype cgroup1_base_files[];
 286 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 287 extern const struct fs_parameter_spec cgroup1_fs_parameters[];
 288
 289 int proc_cgroupstats_show(struct seq_file *m, void *v);
 290 bool cgroup1_ssid_disabled(int ssid);
 291 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
 292 void cgroup1_release_agent(struct work_struct *work);
 293 void cgroup1_check_for_release(struct cgroup *cgrp);
 294 int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
 295 int cgroup1_get_tree(struct fs_context *fc);
 296 int cgroup1_reconfigure(struct fs_context *ctx);
 297
 298 #endif /* __CGROUP_INTERNAL_H */