text: /* 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>
  
  struct task_struct;
  struct rusage;
  union thread_union;
  
  /*
   * 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;
  
  #ifdef CONFIG_PROVE_RCU
  extern int lockdep_tasklist_lock_is_held(void);
  #endif /* #ifdef CONFIG_PROVE_RCU */
  
  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_dead(struct task_struct *p);
  
  void __noreturn do_task_dead(void);
  
  extern void proc_caches_init(void);
  
  extern void fork_init(void);
  
  extern void release_task(struct task_struct * p);
  
  #ifdef CONFIG_HAVE_COPY_THREAD_TLS
  extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
  			struct task_struct *, unsigned long);
  #else
  extern int copy_thread(unsigned long, unsigned long, unsigned long,
  			struct task_struct *);
  
  /* Architectures that haven't opted into copy_thread_tls get the tls argument
   * via pt_regs, so ignore the tls argument passed via C. */
  static inline int copy_thread_tls(
  		unsigned long clone_flags, unsigned long sp, unsigned long arg,
  		struct task_struct *p, unsigned long tls)
  {
  	return copy_thread(clone_flags, sp, arg, p);
  }
  #endif
  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 void do_group_exit(int);
  
  extern void exit_files(struct task_struct *);
  extern void exit_itimers(struct signal_struct *);
  
  extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long);
  extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
  struct task_struct *fork_idle(int);
  extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
  extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
  
  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
  
  #define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)
  
  extern void __put_task_struct(struct task_struct *t);
  
  static inline void put_task_struct(struct task_struct *t)
  {
  	if (atomic_dec_and_test(&t->usage))
  		__put_task_struct(t);
  }
  
  struct task_struct *task_rcu_dereference(struct task_struct **ptask);
  
  #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
  extern int arch_task_struct_size __read_mostly;
  #else
  # define arch_task_struct_size (sizeof(struct task_struct))
  #endif
  
  #ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
  /*
   * If an architecture has not declared a thread_struct whitelist we
   * must assume something there may need to be copied to userspace.
   */
  static inline void arch_thread_struct_whitelist(unsigned long *offset,
  						unsigned long *size)
  {
  	*offset = 0;
  	/* Handle dynamically sized thread_struct. */
  	*size = arch_task_struct_size - offsetof(struct task_struct, thread);
  }
  #endif
  
  #ifdef CONFIG_VMAP_STACK
  static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
  {
  	return t->stack_vm_area;
  }
  #else
  static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
  {
  	return NULL;
  }
  #endif
  
  /*
   * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
   * subscriptions and synchronises with wait4().  Also used in procfs.  Also
   * pins the final release of task.io_context.  Also protects ->cpuset and
   * ->cgroup.subsys[]. And ->vfork_done.
   *
   * Nests both inside and outside of read_lock(&tasklist_lock).
   * It must not be nested with write_lock_irq(&tasklist_lock),
   * neither inside nor outside.
   */
  static inline void task_lock(struct task_struct *p)
  {
  	spin_lock(&p->alloc_lock);
  }
  
  static inline void task_unlock(struct task_struct *p)
  {
  	spin_unlock(&p->alloc_lock);
  }
  
  #endif /* _LINUX_SCHED_TASK_H */
  