/* 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/rcupdate.h>#include <linux/refcount.h>#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;	const char *name;	int exit_signal;	u32 kthread:1;	u32 io_thread:1;	u32 user_worker:1;	u32 no_files:1;	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 idle;	int (*fn)(void *);	void *fn_arg;	struct cgroup *cgrp;	struct css_set *cset;	unsigned int kill_seq;}; /* * 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(u64 clone_flags, struct task_struct *p);extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);extern void sched_cancel_fork(struct task_struct *p);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_THREADextern void exit_thread(struct task_struct *tsk);#elsestatic inline void exit_thread(struct task_struct *tsk){}#endifextern __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 *copy_process(struct pid *pid, int trace, int node,				 struct kernel_clone_args *args);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, const char *name,			    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 */extern void sched_exec(void); static inline struct task_struct *get_task_struct(struct task_struct *t){	refcount_inc(&t->usage);	return t;} static inline struct task_struct *tryget_task_struct(struct task_struct *t){	return refcount_inc_not_zero(&t->usage) ? t : NULL;} 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; 	/*	 * 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).	 *	 * In !RT, it is always safe to call __put_task_struct().	 * Though, in order to simplify the code, resort to the	 * deferred call too.	 *	 * call_rcu() will schedule __put_task_struct_rcu_cb()	 * to be called in process context.	 *	 * __put_task_struct() is called when	 * refcount_dec_and_test(&t->usage) succeeds.	 *	 * 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 with __put_task_struct().	 */	call_rcu(&t->rcu, __put_task_struct_rcu_cb);} DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T)) static inline void put_task_struct_many(struct task_struct *t, int nr){	if (refcount_sub_and_test(nr, &t->usage))		__put_task_struct(t);} void put_task_struct_rcu_user(struct task_struct *task); /* Free all architecture-specific resources held by a thread. */void release_thread(struct task_struct *dead_task); #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCTextern 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_STACKstatic inline struct vm_struct *task_stack_vm_area(const struct task_struct *t){	return t->stack_vm_area;}#elsestatic 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. And ->sysvshm.shm_clist. * * Nests inside 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);} DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T)) #endif /* _LINUX_SCHED_TASK_H */