Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SCHED_TASK_H
3#define _LINUX_SCHED_TASK_H
4
5/*
6 * Interface between the scheduler and various task lifetime (fork()/exit())
7 * functionality:
8 */
9
10#include <linux/sched.h>
11#include <linux/uaccess.h>
12
13struct task_struct;
14struct rusage;
15union thread_union;
16struct css_set;
17
18/* All the bits taken by the old clone syscall. */
19#define CLONE_LEGACY_FLAGS 0xffffffffULL
20
21struct kernel_clone_args {
22 u64 flags;
23 int __user *pidfd;
24 int __user *child_tid;
25 int __user *parent_tid;
26 const char *name;
27 int exit_signal;
28 u32 kthread:1;
29 u32 io_thread:1;
30 u32 user_worker:1;
31 u32 no_files:1;
32 unsigned long stack;
33 unsigned long stack_size;
34 unsigned long tls;
35 pid_t *set_tid;
36 /* Number of elements in *set_tid */
37 size_t set_tid_size;
38 int cgroup;
39 int idle;
40 int (*fn)(void *);
41 void *fn_arg;
42 struct cgroup *cgrp;
43 struct css_set *cset;
44};
45
46/*
47 * This serializes "schedule()" and also protects
48 * the run-queue from deletions/modifications (but
49 * _adding_ to the beginning of the run-queue has
50 * a separate lock).
51 */
52extern rwlock_t tasklist_lock;
53extern spinlock_t mmlist_lock;
54
55extern union thread_union init_thread_union;
56extern struct task_struct init_task;
57
58extern int lockdep_tasklist_lock_is_held(void);
59
60extern asmlinkage void schedule_tail(struct task_struct *prev);
61extern void init_idle(struct task_struct *idle, int cpu);
62
63extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
64extern void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
65extern void sched_post_fork(struct task_struct *p);
66extern void sched_dead(struct task_struct *p);
67
68void __noreturn do_task_dead(void);
69void __noreturn make_task_dead(int signr);
70
71extern void mm_cache_init(void);
72extern void proc_caches_init(void);
73
74extern void fork_init(void);
75
76extern void release_task(struct task_struct * p);
77
78extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
79
80extern void flush_thread(void);
81
82#ifdef CONFIG_HAVE_EXIT_THREAD
83extern void exit_thread(struct task_struct *tsk);
84#else
85static inline void exit_thread(struct task_struct *tsk)
86{
87}
88#endif
89extern __noreturn void do_group_exit(int);
90
91extern void exit_files(struct task_struct *);
92extern void exit_itimers(struct task_struct *);
93
94extern pid_t kernel_clone(struct kernel_clone_args *kargs);
95struct task_struct *copy_process(struct pid *pid, int trace, int node,
96 struct kernel_clone_args *args);
97struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
98struct task_struct *fork_idle(int);
99extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
100 unsigned long flags);
101extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
102extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
103int kernel_wait(pid_t pid, int *stat);
104
105extern void free_task(struct task_struct *tsk);
106
107/* sched_exec is called by processes performing an exec */
108#ifdef CONFIG_SMP
109extern void sched_exec(void);
110#else
111#define sched_exec() {}
112#endif
113
114static inline struct task_struct *get_task_struct(struct task_struct *t)
115{
116 refcount_inc(&t->usage);
117 return t;
118}
119
120extern void __put_task_struct(struct task_struct *t);
121extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
122
123static inline void put_task_struct(struct task_struct *t)
124{
125 if (!refcount_dec_and_test(&t->usage))
126 return;
127
128 /*
129 * In !RT, it is always safe to call __put_task_struct().
130 * Under RT, we can only call it in preemptible context.
131 */
132 if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
133 static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
134
135 lock_map_acquire_try(&put_task_map);
136 __put_task_struct(t);
137 lock_map_release(&put_task_map);
138 return;
139 }
140
141 /*
142 * under PREEMPT_RT, we can't call put_task_struct
143 * in atomic context because it will indirectly
144 * acquire sleeping locks.
145 *
146 * call_rcu() will schedule delayed_put_task_struct_rcu()
147 * to be called in process context.
148 *
149 * __put_task_struct() is called when
150 * refcount_dec_and_test(&t->usage) succeeds.
151 *
152 * This means that it can't "conflict" with
153 * put_task_struct_rcu_user() which abuses ->rcu the same
154 * way; rcu_users has a reference so task->usage can't be
155 * zero after rcu_users 1 -> 0 transition.
156 *
157 * delayed_free_task() also uses ->rcu, but it is only called
158 * when it fails to fork a process. Therefore, there is no
159 * way it can conflict with put_task_struct().
160 */
161 call_rcu(&t->rcu, __put_task_struct_rcu_cb);
162}
163
164DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
165
166static inline void put_task_struct_many(struct task_struct *t, int nr)
167{
168 if (refcount_sub_and_test(nr, &t->usage))
169 __put_task_struct(t);
170}
171
172void put_task_struct_rcu_user(struct task_struct *task);
173
174/* Free all architecture-specific resources held by a thread. */
175void release_thread(struct task_struct *dead_task);
176
177#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
178extern int arch_task_struct_size __read_mostly;
179#else
180# define arch_task_struct_size (sizeof(struct task_struct))
181#endif
182
183#ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
184/*
185 * If an architecture has not declared a thread_struct whitelist we
186 * must assume something there may need to be copied to userspace.
187 */
188static inline void arch_thread_struct_whitelist(unsigned long *offset,
189 unsigned long *size)
190{
191 *offset = 0;
192 /* Handle dynamically sized thread_struct. */
193 *size = arch_task_struct_size - offsetof(struct task_struct, thread);
194}
195#endif
196
197#ifdef CONFIG_VMAP_STACK
198static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
199{
200 return t->stack_vm_area;
201}
202#else
203static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
204{
205 return NULL;
206}
207#endif
208
209/*
210 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
211 * subscriptions and synchronises with wait4(). Also used in procfs. Also
212 * pins the final release of task.io_context. Also protects ->cpuset and
213 * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
214 *
215 * Nests both inside and outside of read_lock(&tasklist_lock).
216 * It must not be nested with write_lock_irq(&tasklist_lock),
217 * neither inside nor outside.
218 */
219static inline void task_lock(struct task_struct *p)
220{
221 spin_lock(&p->alloc_lock);
222}
223
224static inline void task_unlock(struct task_struct *p)
225{
226 spin_unlock(&p->alloc_lock);
227}
228
229#endif /* _LINUX_SCHED_TASK_H */