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 /*
  12  * A cgroup can be associated with multiple css_sets as different tasks may
  13  * belong to different cgroups on different hierarchies.  In the other
  14  * direction, a css_set is naturally associated with multiple cgroups.
  15  * This M:N relationship is represented by the following link structure
  16  * which exists for each association and allows traversing the associations
  17  * from both sides.
  18  */
  19 struct cgrp_cset_link {
  20         /* the cgroup and css_set this link associates */
  21         struct cgroup           *cgrp;
  22         struct css_set          *cset;
  23
  24         /* list of cgrp_cset_links anchored at cgrp->cset_links */
  25         struct list_head        cset_link;
  26
  27         /* list of cgrp_cset_links anchored at css_set->cgrp_links */
  28         struct list_head        cgrp_link;
  29 };
  30
  31 /* used to track tasks and csets during migration */
  32 struct cgroup_taskset {
  33         /* the src and dst cset list running through cset->mg_node */
  34         struct list_head        src_csets;
  35         struct list_head        dst_csets;
  36
  37         /* the number of tasks in the set */
  38         int                     nr_tasks;
  39
  40         /* the subsys currently being processed */
  41         int                     ssid;
  42
  43         /*
  44          * Fields for cgroup_taskset_*() iteration.
  45          *
  46          * Before migration is committed, the target migration tasks are on
  47          * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
  48          * the csets on ->dst_csets.  ->csets point to either ->src_csets
  49          * or ->dst_csets depending on whether migration is committed.
  50          *
  51          * ->cur_csets and ->cur_task point to the current task position
  52          * during iteration.
  53          */
  54         struct list_head        *csets;
  55         struct css_set          *cur_cset;
  56         struct task_struct      *cur_task;
  57 };
  58
  59 /* migration context also tracks preloading */
  60 struct cgroup_mgctx {
  61         /*
  62          * Preloaded source and destination csets.  Used to guarantee
  63          * atomic success or failure on actual migration.
  64          */
  65         struct list_head        preloaded_src_csets;
  66         struct list_head        preloaded_dst_csets;
  67
  68         /* tasks and csets to migrate */
  69         struct cgroup_taskset   tset;
  70
  71         /* subsystems affected by migration */
  72         u16                     ss_mask;
  73 };
  74
  75 #define CGROUP_TASKSET_INIT(tset)                                               \
  76 {                                                                               \
  77         .src_csets              = LIST_HEAD_INIT(tset.src_csets),               \
  78         .dst_csets              = LIST_HEAD_INIT(tset.dst_csets),               \
  79         .csets                  = &tset.src_csets,                              \
  80 }
  81
  82 #define CGROUP_MGCTX_INIT(name)                                                 \
  83 {                                                                               \
  84         LIST_HEAD_INIT(name.preloaded_src_csets),                               \
  85         LIST_HEAD_INIT(name.preloaded_dst_csets),                               \
  86         CGROUP_TASKSET_INIT(name.tset),                                         \
  87 }
  88
  89 #define DEFINE_CGROUP_MGCTX(name)                                               \
  90         struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
  91
  92 struct cgroup_sb_opts {
  93         u16 subsys_mask;
  94         unsigned int flags;
  95         char *release_agent;
  96         bool cpuset_clone_children;
  97         char *name;
  98         /* User explicitly requested empty subsystem */
  99         bool none;
 100 };
 101
 102 extern struct mutex cgroup_mutex;
 103 extern spinlock_t css_set_lock;
 104 extern struct cgroup_subsys *cgroup_subsys[];
 105 extern struct list_head cgroup_roots;
 106 extern struct file_system_type cgroup_fs_type;
 107
 108 /* iterate across the hierarchies */
 109 #define for_each_root(root)                                             \
 110         list_for_each_entry((root), &cgroup_roots, root_list)
 111
 112 /**
 113  * for_each_subsys - iterate all enabled cgroup subsystems
 114  * @ss: the iteration cursor
 115  * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
 116  */
 117 #define for_each_subsys(ss, ssid)                                       \
 118         for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&                \
 119              (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
 120
 121 static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 122 {
 123         return !(cgrp->self.flags & CSS_ONLINE);
 124 }
 125
 126 static inline bool notify_on_release(const struct cgroup *cgrp)
 127 {
 128         return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 129 }
 130
 131 void put_css_set_locked(struct css_set *cset);
 132
 133 static inline void put_css_set(struct css_set *cset)
 134 {
 135         unsigned long flags;
 136
 137         /*
 138          * Ensure that the refcount doesn't hit zero while any readers
 139          * can see it. Similar to atomic_dec_and_lock(), but for an
 140          * rwlock
 141          */
 142         if (refcount_dec_not_one(&cset->refcount))
 143                 return;
 144
 145         spin_lock_irqsave(&css_set_lock, flags);
 146         put_css_set_locked(cset);
 147         spin_unlock_irqrestore(&css_set_lock, flags);
 148 }
 149
 150 /*
 151  * refcounted get/put for css_set objects
 152  */
 153 static inline void get_css_set(struct css_set *cset)
 154 {
 155         refcount_inc(&cset->refcount);
 156 }
 157
 158 bool cgroup_ssid_enabled(int ssid);
 159 bool cgroup_on_dfl(const struct cgroup *cgrp);
 160 bool cgroup_is_thread_root(struct cgroup *cgrp);
 161 bool cgroup_is_threaded(struct cgroup *cgrp);
 162
 163 struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
 164 struct cgroup *task_cgroup_from_root(struct task_struct *task,
 165                                      struct cgroup_root *root);
 166 struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
 167 void cgroup_kn_unlock(struct kernfs_node *kn);
 168 int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
 169                           struct cgroup_namespace *ns);
 170
 171 void cgroup_free_root(struct cgroup_root *root);
 172 void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
 173 int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags);
 174 int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
 175 struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
 176                                struct cgroup_root *root, unsigned long magic,
 177                                struct cgroup_namespace *ns);
 178
 179 int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
 180 void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
 181 void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
 182                             struct cgroup_mgctx *mgctx);
 183 int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
 184 int cgroup_migrate(struct task_struct *leader, bool threadgroup,
 185                    struct cgroup_mgctx *mgctx);
 186
 187 int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
 188                        bool threadgroup);
 189 struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
 190         __acquires(&cgroup_threadgroup_rwsem);
 191 void cgroup_procs_write_finish(struct task_struct *task)
 192         __releases(&cgroup_threadgroup_rwsem);
 193
 194 void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 195
 196 int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
 197 int cgroup_rmdir(struct kernfs_node *kn);
 198 int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 199                      struct kernfs_root *kf_root);
 200
 201 int cgroup_task_count(const struct cgroup *cgrp);
 202
 203 /*
 204  * namespace.c
 205  */
 206 extern const struct proc_ns_operations cgroupns_operations;
 207
 208 /*
 209  * cgroup-v1.c
 210  */
 211 extern struct cftype cgroup1_base_files[];
 212 extern const struct file_operations proc_cgroupstats_operations;
 213 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 214
 215 bool cgroup1_ssid_disabled(int ssid);
 216 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
 217 void cgroup1_release_agent(struct work_struct *work);
 218 void cgroup1_check_for_release(struct cgroup *cgrp);
 219 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
 220                              void *data, unsigned long magic,
 221                              struct cgroup_namespace *ns);
 222
 223 #endif /* __CGROUP_INTERNAL_H */