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/rcupdate.h>
11#include <linux/refcount.h>
12#include <linux/sched.h>
13#include <linux/uaccess.h>
14
15struct task_struct;
16struct rusage;
17union thread_union;
18struct css_set;
19
20/* All the bits taken by the old clone syscall. */
21#define CLONE_LEGACY_FLAGS 0xffffffffULL
22
23struct kernel_clone_args {
24 u64 flags;
25 int __user *pidfd;
26 int __user *child_tid;
27 int __user *parent_tid;
28 const char *name;
29 int exit_signal;
30 u32 kthread:1;
31 u32 io_thread:1;
32 u32 user_worker:1;
33 u32 no_files:1;
34 unsigned long stack;
35 unsigned long stack_size;
36 unsigned long tls;
37 pid_t *set_tid;
38 /* Number of elements in *set_tid */
39 size_t set_tid_size;
40 int cgroup;
41 int idle;
42 int (*fn)(void *);
43 void *fn_arg;
44 struct cgroup *cgrp;
45 struct css_set *cset;
46};
47
48/*
49 * This serializes "schedule()" and also protects
50 * the run-queue from deletions/modifications (but
51 * _adding_ to the beginning of the run-queue has
52 * a separate lock).
53 */
54extern rwlock_t tasklist_lock;
55extern spinlock_t mmlist_lock;
56
57extern union thread_union init_thread_union;
58extern struct task_struct init_task;
59
60extern int lockdep_tasklist_lock_is_held(void);
61
62extern asmlinkage void schedule_tail(struct task_struct *prev);
63extern void init_idle(struct task_struct *idle, int cpu);
64
65extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
66extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
67extern void sched_cancel_fork(struct task_struct *p);
68extern void sched_post_fork(struct task_struct *p);
69extern void sched_dead(struct task_struct *p);
70
71void __noreturn do_task_dead(void);
72void __noreturn make_task_dead(int signr);
73
74extern void mm_cache_init(void);
75extern void proc_caches_init(void);
76
77extern void fork_init(void);
78
79extern void release_task(struct task_struct * p);
80
81extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
82
83extern void flush_thread(void);
84
85#ifdef CONFIG_HAVE_EXIT_THREAD
86extern void exit_thread(struct task_struct *tsk);
87#else
88static inline void exit_thread(struct task_struct *tsk)
89{
90}
91#endif
92extern __noreturn void do_group_exit(int);
93
94extern void exit_files(struct task_struct *);
95extern void exit_itimers(struct task_struct *);
96
97extern pid_t kernel_clone(struct kernel_clone_args *kargs);
98struct task_struct *copy_process(struct pid *pid, int trace, int node,
99 struct kernel_clone_args *args);
100struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
101struct task_struct *fork_idle(int);
102extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
103 unsigned long flags);
104extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
105extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
106int kernel_wait(pid_t pid, int *stat);
107
108extern void free_task(struct task_struct *tsk);
109
110/* sched_exec is called by processes performing an exec */
111#ifdef CONFIG_SMP
112extern void sched_exec(void);
113#else
114#define sched_exec() {}
115#endif
116
117static inline struct task_struct *get_task_struct(struct task_struct *t)
118{
119 refcount_inc(&t->usage);
120 return t;
121}
122
123static inline struct task_struct *tryget_task_struct(struct task_struct *t)
124{
125 return refcount_inc_not_zero(&t->usage) ? t : NULL;
126}
127
128extern void __put_task_struct(struct task_struct *t);
129extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
130
131static inline void put_task_struct(struct task_struct *t)
132{
133 if (!refcount_dec_and_test(&t->usage))
134 return;
135
136 /*
137 * In !RT, it is always safe to call __put_task_struct().
138 * Under RT, we can only call it in preemptible context.
139 */
140 if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
141 static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
142
143 lock_map_acquire_try(&put_task_map);
144 __put_task_struct(t);
145 lock_map_release(&put_task_map);
146 return;
147 }
148
149 /*
150 * under PREEMPT_RT, we can't call put_task_struct
151 * in atomic context because it will indirectly
152 * acquire sleeping locks.
153 *
154 * call_rcu() will schedule delayed_put_task_struct_rcu()
155 * to be called in process context.
156 *
157 * __put_task_struct() is called when
158 * refcount_dec_and_test(&t->usage) succeeds.
159 *
160 * This means that it can't "conflict" with
161 * put_task_struct_rcu_user() which abuses ->rcu the same
162 * way; rcu_users has a reference so task->usage can't be
163 * zero after rcu_users 1 -> 0 transition.
164 *
165 * delayed_free_task() also uses ->rcu, but it is only called
166 * when it fails to fork a process. Therefore, there is no
167 * way it can conflict with put_task_struct().
168 */
169 call_rcu(&t->rcu, __put_task_struct_rcu_cb);
170}
171
172DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
173
174static inline void put_task_struct_many(struct task_struct *t, int nr)
175{
176 if (refcount_sub_and_test(nr, &t->usage))
177 __put_task_struct(t);
178}
179
180void put_task_struct_rcu_user(struct task_struct *task);
181
182/* Free all architecture-specific resources held by a thread. */
183void release_thread(struct task_struct *dead_task);
184
185#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
186extern int arch_task_struct_size __read_mostly;
187#else
188# define arch_task_struct_size (sizeof(struct task_struct))
189#endif
190
191#ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
192/*
193 * If an architecture has not declared a thread_struct whitelist we
194 * must assume something there may need to be copied to userspace.
195 */
196static inline void arch_thread_struct_whitelist(unsigned long *offset,
197 unsigned long *size)
198{
199 *offset = 0;
200 /* Handle dynamically sized thread_struct. */
201 *size = arch_task_struct_size - offsetof(struct task_struct, thread);
202}
203#endif
204
205#ifdef CONFIG_VMAP_STACK
206static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
207{
208 return t->stack_vm_area;
209}
210#else
211static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
212{
213 return NULL;
214}
215#endif
216
217/*
218 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
219 * subscriptions and synchronises with wait4(). Also used in procfs. Also
220 * pins the final release of task.io_context. Also protects ->cpuset and
221 * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
222 *
223 * Nests both inside and outside of read_lock(&tasklist_lock).
224 * It must not be nested with write_lock_irq(&tasklist_lock),
225 * neither inside nor outside.
226 */
227static inline void task_lock(struct task_struct *p)
228{
229 spin_lock(&p->alloc_lock);
230}
231
232static inline void task_unlock(struct task_struct *p)
233{
234 spin_unlock(&p->alloc_lock);
235}
236
237DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T))
238
239#endif /* _LINUX_SCHED_TASK_H */