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  *   	ˆl–Ü4ý( ©³( 	Å€fàB¦-ÿ¿ƒq‡_†I|¥+ÄÃ §    	/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SCHED_TASK_H
#define _LINUX_SCHED_TASK_H

/*
 * Interface between the scheduler and various task lifetime (fork()/exit())
 * functionality:
 */

#include <linux/sched.h>
#include <linux/uaccess.h>

struct task_struct;
struct rusage;
union thread_union;
struct css_set;

/* All the bits taken by the old clone syscall. */
#define CLONE_LEGACY_FLAGS 0xffffffffULL

struct kernel_clone_args {
	u64 flags;
	int __user *pidfd;
	int __user *child_tid;
	int __user *parent_tid;
	int exit_signal;
	unsigned long stack;
	unsigned long stack_size;
	unsigned long tls;
	pid_t *set_tid;
	/* Number of elements in *set_tid */
	size_t set_tid_size;
	int cgroup;
	int io_thread;
	int kthread;
	int (*fn)(void *);
	void *fn_arg;
	struct cgroup *cgrp;
	struct css_set *cset;
};

/*
 * This serializes "schedule()" and also protects
 * the run-queue from deletions/modifications (but
 * _adding_ to the beginning of the run-queue has
 * a separate lock).
 */
extern rwlock_t tasklist_lock;
extern spinlock_t mmlist_lock;

extern union thread_union init_thread_union;
extern struct task_struct init_task;

extern int lockdep_tasklist_lock_is_held(void);

extern asmlinkage void schedule_tail(struct task_struct *prev);
extern void init_idle(struct task_struct *idle, int cpu);

extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
extern void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
extern void sched_post_fork(struct task_struct *p);
extern void sched_dead(struct task_struct *p);

void __noreturn do_task_dead(void);
void __noreturn make_task_dead(int signr);

extern void mm_cache_init(void);
extern void proc_caches_init(void);

extern void fork_init(void);

extern void release_task(struct task_struct * p);

extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);

extern void flush_thread(void);

#ifdef CONFIG_HAVE_EXIT_THREAD
extern void exit_thread(struct task_struct *tsk);
#else
static inline void exit_thread(struct task_struct *tsk)
{
}
#endif
extern __noreturn void do_group_exit(int);

extern void exit_files(struct task_struct *);
extern void exit_itimers(struct task_struct *);

extern pid_t kernel_clone(struct kernel_clone_args *kargs);
struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
struct task_struct *fork_idle(int);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
int kernel_wait(pid_t pid, int *stat);

extern void free_task(struct task_struct *tsk);

/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
extern void sched_exec(void);
#else
#define sched_exec()   {}
#endif

static inline struct task_struct *get_task_struct(struct task_struct *t)
{
	refcount_inc(&t->usage);
	return t;
}

extern void __put_task_struct(struct task_struct *t);
extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);

static inline void put_task_struct(struct task_struct *t)
{
	if (!refcount_dec_and_test(&t->usage))
		return;

	/*
	 * In !RT, it is always safe to call __put_task_struct().
	 * __put_task_struct() is called when
	 * refcount_dec_and_test(&t->usage) succeeds.
	 *
	 * Under PREEMPT_RT, we can't call __put_task_struct
	 * in atomic context because it will indirectly
	 * acquire sleeping locks. The same is true if the
	 * current process has a mutex enqueued (blocked on
	 * a PI chain).
	 *
	 * call_rcu() will schedule __put_task_struct_rcu_cb()
	 * to be called in process context.
	 *
	 * This means that it can't "conflict" with
	 * put_task_struct_rcu_user() which abuses ->rcu the same
	 * way; rcu_users has a reference so task->usage can't be
	 * zero after rcu_users 1 -> 0 transition.
	 *
	 * delayed_free_task() also uses ->rcu, but it is only called
	 * when it fails to fork a process. Therefore, there is no
	 * way it can conflict wi