/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __CGROUP_INTERNAL_H
#define __CGROUP_INTERNAL_H

#include <linux/cgroup.h>
#include <linux/kernfs.h>
#include <linux/workqueue.h>
#include <linux/list.h>
#include <linux/refcount.h>
#include <linux/fs_parser.h>

#define TRACE_CGROUP_PATH_LEN 1024
extern spinlock_t trace_cgroup_path_lock;
extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
extern void __init enable_debug_cgroup(void);

/*
 * cgroup_path() takes a spin lock. It is good practice not to take
 * spin locks within trace point handlers, as they are mostly hidden
 * from normal view. As cgroup_path() can take the kernfs_rename_lock
 * spin lock, it is best to not call that function from the trace event
 * handler.
 *
 * Note: trace_cgroup_##type##_enabled() is a static branch that will only
 *       be set when the trace event is enabled.
 */
#define TRACE_CGROUP_PATH(type, cgrp, ...)                              \
        do {                                                            \
                if (trace_cgroup_##type##_enabled()) {                  \
                        unsigned long flags;                            \
                        spin_lock_irqsave(&trace_cgroup_path_lock,      \
                                          flags);                       \
                        cgroup_path(cgrp, trace_cgroup_path,            \
                                    TRACE_CGROUP_PATH_LEN);             \
                        trace_cgroup_##type(cgrp, trace_cgroup_path,    \
                                            ##__VA_ARGS__);             \
                        spin_unlock_irqrestore(&trace_cgroup_path_lock, \
                                               flags);                  \
                }                                                       \
        } while (0)

/*
 * The cgroup filesystem superblock creation/mount context.
 */
struct cgroup_fs_context {
        struct kernfs_fs_context kfc;
        struct cgroup_root      *root;
        struct cgroup_namespace *ns;
        unsigned int    flags;                  /* CGRP_ROOT_* flags */

        /* cgroup1 bits */
        bool            cpuset_clone_children;
        bool            none;                   /* User explicitly requested empty subsystem */
        bool            all_ss;                 /* Seen 'all' option */
        u32             subsys_mask;            /* Selected subsystems */
        char            *name;                  /* Hierarchy name */
        char            *release_agent;         /* Path for release notifications */
};

static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
{
        struct kernfs_fs_context *kfc = fc->fs_private;

        return container_of(kfc, struct cgroup_fs_context, kfc);
}

struct cgroup_pidlist;

struct cgroup_file_ctx {
        struct cgroup_namespace *ns;

        struct {
                void                    *trigger;
        } psi;

        struct {
                bool                    started;
                struct css_task_iter    iter;
        } procs;

        struct {
                struct cgroup_pidlist   *pidlist;
        } procs1;

        struct cgroup_of_peak peak;
};

/*
 * A cgroup can be associated with multiple css_sets as different tasks may
 * belong to different cgroups on different hierarchies.  In the other
 * direction, a css_set is naturally associated with multiple cgroups.
 * This M:N relationship is represented by the following link structure
 * which exists for each association and allows traversing the associations
 * from both sides.
 */
struct cgrp_cset_link {
        /* the cgroup and css_set this link associates */
        struct cgroup           *cgrp;
        struct css_set          *cset;

        /* list of cgrp_cset_links anchored at cgrp->cset_links */
        struct list_head        cset_link;

        /* list of cgrp_cset_links anchored at css_set->cgrp_links */
        struct list_head        cgrp_link;
};

/* used to track tasks and csets during migration */
struct cgroup_taskset {
        /* the src and dst cset list running through cset->mg_node */
        struct list_head        src_csets;
        struct list_head        dst_csets;

        /* the number of tasks in the set */
        int                     nr_tasks;

        /* the subsys currently being processed */
        int                     ssid;

        /*
         * Fields for cgroup_taskset_*() iteration.
         *
         * Before migration is committed, the target migration tasks are on
         * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
         * the csets on ->dst_csets.  ->csets point to either ->src_csets
         * or ->dst_csets depending on whether migration is committed.
         *
         * ->cur_csets and ->cur_task point to the current task position
         * during iteration.
         */
        struct list_head        *csets;
        struct css_set          *cur_cset;
        struct task_struct      *cur_task;
};

/* migration context also tracks preloading */
struct cgroup_mgctx {
        /*
         * Preloaded source and destination csets.  Used to guarantee
         * atomic success or failure on actual migration.
         */
        struct list_head        preloaded_src_csets;
        struct list_head        preloaded_dst_csets;

        /* tasks and csets to migrate */
        struct cgroup_taskset   tset;

        /* subsystems affected by migration */
        u32                     ss_mask;
};

#define CGROUP_TASKSET_INIT(tset)                                               \
{                                                                               \
        .src_csets              = LIST_HEAD_INIT(tset.src_csets),               \
        .dst_csets              = LIST_HEAD_INIT(tset.dst_csets),               \
        .csets                  = &tset.src_csets,                              \
}

#define CGROUP_MGCTX_INIT(name)                                                 \
{                                                                               \
        LIST_HEAD_INIT(name.preloaded_src_csets),                               \
        LIST_HEAD_INIT(name.preloaded_dst_csets),                               \
        CGROUP_TASKSET_INIT(name.tset),                                         \
}

#define DEFINE_CGROUP_MGCTX(name)                                               \
        struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)

extern struct cgroup_subsys *cgroup_subsys[];
extern struct list_head cgroup_roots;
extern bool cgrp_dfl_visible;

/* iterate across the hierarchies */
#define for_each_root(root)                                             \
        list_for_each_entry_rcu((root), &cgroup_roots, root_list,       \
                                lockdep_is_held(&cgroup_mutex))

/**
 * for_each_subsys - iterate all enabled cgroup subsystems
 * @ss: the iteration cursor
 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
 */
#define for_each_subsys(ss, ssid)                                       \
        for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&                \
             (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)

static inline bool cgroup_is_dead(const struct cgroup *cgrp)
{
        return !(cgrp->self.flags & CSS_ONLINE);
}

static inline bool notify_on_release(const struct cgroup *cgrp)
{
        return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
}

void put_css_set_locked(struct css_set *cset);

static inline void put_css_set(struct css_set *cset)
{
        unsigned long flags;

        /*
         * Ensure that the refcount doesn't hit zero while any readers
         * can see it. Similar to atomic_dec_and_lock(), but for an
         * rwlock
         */
        if (refcount_dec_not_one(&cset->refcount))
                return;

        spin_lock_irqsave(&css_set_lock, flags);
        put_css_set_locked(cset);
        spin_unlock_irqrestore(&css_set_lock, flags);
}

/*
 * refcounted get/put for css_set objects
 */
static inline void get_css_set(struct css_set *cset)
{
        refcount_inc(&cset->refcount);
}

bool cgroup_ssid_enabled(int ssid);
bool cgroup_on_dfl(const struct cgroup *cgrp);

struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
struct cgroup *task_cgroup_from_root(struct task_struct *task,
                                     struct cgroup_root *root);
struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
void cgroup_kn_unlock(struct kernfs_node *kn);
int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
                          struct cgroup_namespace *ns);

void cgroup_favor_dynmods(struct cgroup_root *root, bool favor);
void cgroup_free_root(struct cgroup_root *root);
void init_cgroup_root(struct cgroup_fs_context *ctx);
int cgroup_setup_root(struct cgroup_root *root, u32 ss_mask);
int rebind_subsystems(struct cgroup_root *dst_root, u32 ss_mask);
int cgroup_do_get_tree(struct fs_context *fc);

int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
                            struct cgroup_mgctx *mgctx);
int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
int cgroup_migrate(struct task_struct *leader, bool threadgroup,
                   struct cgroup_mgctx *mgctx);

int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
                       bool threadgroup);
void cgroup_attach_lock(enum cgroup_attach_lock_mode lock_mode,
                        struct task_struct *tsk);
void cgroup_attach_unlock(enum cgroup_attach_lock_mode lock_mode,
                          struct task_struct *tsk);
struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
                                             enum cgroup_attach_lock_mode *lock_mode)
        __acquires(&cgroup_threadgroup_rwsem);
void cgroup_procs_write_finish(struct task_struct *task,
                               enum cgroup_attach_lock_mode lock_mode)
        __releases(&cgroup_threadgroup_rwsem);

void cgroup_lock_and_drain_offline(struct cgroup *cgrp);

int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
int cgroup_rmdir(struct kernfs_node *kn);
int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
                     struct kernfs_root *kf_root);

int __cgroup_task_count(const struct cgroup *cgrp);
int cgroup_task_count(const struct cgroup *cgrp);

/*
 * rstat.c
 */
int css_rstat_init(struct cgroup_subsys_state *css);
void css_rstat_exit(struct cgroup_subsys_state *css);
int ss_rstat_init(struct cgroup_subsys *ss);
void cgroup_base_stat_cputime_show(struct seq_file *seq);

/*
 * namespace.c
 */
extern const struct proc_ns_operations cgroupns_operations;

/*
 * cgroup-v1.c
 */
extern struct cftype cgroup1_base_files[];
extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
extern const struct fs_parameter_spec cgroup1_fs_parameters[];

int proc_cgroupstats_show(struct seq_file *m, void *v);
bool cgroup1_ssid_disabled(int ssid);
void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
void cgroup1_release_agent(struct work_struct *work);
void cgroup1_check_for_release(struct cgroup *cgrp);
int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param);
int cgroup1_get_tree(struct fs_context *fc);
int cgroup1_reconfigure(struct fs_context *ctx);

#endif /* __CGROUP_INTERNAL_H */