LXR linux/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
  13extern spinlock_t trace_cgroup_path_lock;
  14extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
  15extern bool cgroup_debug;
  16extern 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 */
  46struct 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
  61static 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 */
  76struct 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 */
  89struct 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 */
 117struct 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
 149extern struct mutex cgroup_mutex;
 150extern spinlock_t css_set_lock;
 151extern struct cgroup_subsys *cgroup_subsys[];
 152extern struct list_head cgroup_roots;
 153extern 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
 168static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 169{
 170        return !(cgrp->self.flags & CSS_ONLINE);
 171}
 172
 173static inline bool notify_on_release(const struct cgroup *cgrp)
 174{
 175        return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 176}
 177
 178void put_css_set_locked(struct css_set *cset);
 179
 180static 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 */
 200static inline void get_css_set(struct css_set *cset)
 201{
 202        refcount_inc(&cset->refcount);
 203}
 204
 205bool cgroup_ssid_enabled(int ssid);
 206bool cgroup_on_dfl(const struct cgroup *cgrp);
 207bool cgroup_is_thread_root(struct cgroup *cgrp);
 208bool cgroup_is_threaded(struct cgroup *cgrp);
 209
 210struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
 211struct cgroup *task_cgroup_from_root(struct task_struct *task,
 212                                     struct cgroup_root *root);
 213struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
 214void cgroup_kn_unlock(struct kernfs_node *kn);
 215int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
 216                          struct cgroup_namespace *ns);
 217
 218void cgroup_free_root(struct cgroup_root *root);
 219void init_cgroup_root(struct cgroup_fs_context *ctx);
 220int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);
 221int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
 222int cgroup_do_get_tree(struct fs_context *fc);
 223
 224int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
 225void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
 226void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
 227                            struct cgroup_mgctx *mgctx);
 228int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
 229int cgroup_migrate(struct task_struct *leader, bool threadgroup,
 230                   struct cgroup_mgctx *mgctx);
 231
 232int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
 233                       bool threadgroup);
 234struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
 235                                             bool *locked)
 236        __acquires(&cgroup_threadgroup_rwsem);
 237void cgroup_procs_write_finish(struct task_struct *task, bool locked)
 238        __releases(&cgroup_threadgroup_rwsem);
 239
 240void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 241
 242int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
 243int cgroup_rmdir(struct kernfs_node *kn);
 244int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 245                     struct kernfs_root *kf_root);
 246
 247int __cgroup_task_count(const struct cgroup *cgrp);
 248int cgroup_task_count(const struct cgroup *cgrp);
 249
 250/*
 251 * rstat.c
 252 */
 253int cgroup_rstat_init(struct cgroup *cgrp);
 254void cgroup_rstat_exit(struct cgroup *cgrp);
 255void cgroup_rstat_boot(void);
 256void cgroup_base_stat_cputime_show(struct seq_file *seq);
 257
 258/*
 259 * namespace.c
 260 */
 261extern const struct proc_ns_operations cgroupns_operations;
 262
 263/*
 264 * cgroup-v1.c
 265 */
 266extern struct cftype cgroup1_base_files[];
 267extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 268extern const struct fs_parameter_spec cgroup1_fs_parameters[];
 269
 270int proc_cgroupstats_show(struct seq_file *m, void *v);
 271bool cgroup1_ssid_disabled(int ssid);
 272void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
 273void cgroup1_release_agent(struct work_struct *work);
 274void cgroup1_check_for_release(struct cgroup *cgrp);
 275int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
 276int cgroup1_get_tree(struct fs_context *fc);
 277int cgroup1_reconfigure(struct fs_context *ctx);
 278
 279#endif /* __CGROUP_INTERNAL_H */
 280