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