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/* 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;
};
/*
* 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 *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 */
#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().
* Under RT, we can only call it in preemptible context.
*/
if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
lock_map_acquire_try(&put_task_map);
__put_task_struct(t);
lock_map_release(&put_task_map);
return;
}
/*
* under PREEMPT_RT, we can't call put_task_struct
* in atomic context because it will indirectly
* acquire sleeping locks.
*
* call_rcu() will schedule delayed_put_task_struct_rcu()
* 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_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. And ->sysvshm.shm_clist.
*
* 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);
}
DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T))
#endif /* _LINUX_SCHED_TASK_H */