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 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
  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
 168 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 169 {
 170         return !(cgrp->self.flags & CSS_ONLINE);
 171 }
 172
 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
 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  */
 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                                              bool *locked)
 236         __acquires(&cgroup_threadgroup_rwsem);
 237 void cgroup_procs_write_finish(struct task_struct *task, bool locked)
 238         __releases(&cgroup_threadgroup_rwsem);
 239
 240 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 241
 242 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
 243 int cgroup_rmdir(struct kernfs_node *kn);
 244 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 245                      struct kernfs_root *kf_root);
 246
 247 int __cgroup_task_count(const struct cgroup *cgrp);
 248 int cgroup_task_count(const struct cgroup *cgrp);
 249
 250 /*
 251  * rstat.c
 252  */
 253 int cgroup_rstat_init(struct cgroup *cgrp);
 254 void cgroup_rstat_exit(struct cgroup *cgrp);
 255 void cgroup_rstat_boot(void);
 256 void cgroup_base_stat_cputime_show(struct seq_file *seq);
 257
 258 /*
 259  * namespace.c
 260  */
 261 extern const struct proc_ns_operations cgroupns_operations;
 262
 263 /*
 264  * cgroup-v1.c
 265  */
 266 extern struct cftype cgroup1_base_files[];
 267 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 268 extern const struct fs_parameter_spec cgroup1_fs_parameters[];
 269
 270 int proc_cgroupstats_show(struct seq_file *m, void *v);
 271 bool cgroup1_ssid_disabled(int ssid);
 272 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
 273 void cgroup1_release_agent(struct work_struct *work);
 274 void cgroup1_check_for_release(struct cgroup *cgrp);
 275 int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
 276 int cgroup1_get_tree(struct fs_context *fc);
 277 int cgroup1_reconfigure(struct fs_context *ctx);
 278
 279 #endif /* __CGROUP_INTERNAL_H */