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
  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
 147 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 148 {
 149         return !(cgrp->self.flags & CSS_ONLINE);
 150 }
 151
 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
 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  */
 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 */