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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 
13 struct task_struct;
14 struct rusage;
15 union thread_union;
16 struct css_set;
17 
18 /* All the bits taken by the old clone syscall. */
19 #define CLONE_LEGACY_FLAGS 0xffffffffULL
20 
21 struct kernel_clone_args {
22 	u64 flags;
23 	int __user *pidfd;
24 	int __user *child_tid;
25 	int __user *parent_tid;
26 	int exit_signal;
27 	unsigned long stack;
28 	unsigned long stack_size;
29 	unsigned long tls;
30 	pid_t *set_tid;
31 	/* Number of elements in *set_tid */
32 	size_t set_tid_size;
33 	int cgroup;
34 	int io_thread;
35 	struct cgroup *cgrp;
36 	struct css_set *cset;
37 };
38 
39 /*
40  * This serializes "schedule()" and also protects
41  * the run-queue from deletions/modifications (but
42  * _adding_ to the beginning of the run-queue has
43  * a separate lock).
44  */
45 extern rwlock_t tasklist_lock;
46 extern spinlock_t mmlist_lock;
47 
48 extern union thread_union init_thread_union;
49 extern struct task_struct init_task;
50 
51 #ifdef CONFIG_PROVE_RCU
52 extern int lockdep_tasklist_lock_is_held(void);
53 #endif /* #ifdef CONFIG_PROVE_RCU */
54 
55 extern asmlinkage void schedule_tail(struct task_struct *prev);
56 extern void init_idle(struct task_struct *idle, int cpu);
57 
58 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
59 extern void sched_post_fork(struct task_struct *p,
60 			    struct kernel_clone_args *kargs);
61 extern void sched_dead(struct task_struct *p);
62 
63 void __noreturn do_task_dead(void);
64 
65 extern void proc_caches_init(void);
66 
67 extern void fork_init(void);
68 
69 extern void release_task(struct task_struct * p);
70 
71 extern int copy_thread(unsigned long, unsigned long, unsigned long,
72 		       struct task_struct *, unsigned long);
73 
74 extern void flush_thread(void);
75 
76 #ifdef CONFIG_HAVE_EXIT_THREAD
77 extern void exit_thread(struct task_struct *tsk);
78 #else
exit_thread(struct task_struct * tsk)79 static inline void exit_thread(struct task_struct *tsk)
80 {
81 }
82 #endif
83 extern void do_group_exit(int);
84 
85 extern void exit_files(struct task_struct *);
86 extern void exit_itimers(struct task_struct *);
87 
88 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
89 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
90 struct task_struct *fork_idle(int);
91 struct mm_struct *copy_init_mm(void);
92 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
93 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
94 int kernel_wait(pid_t pid, int *stat);
95 
96 extern void free_task(struct task_struct *tsk);
97 
98 /* sched_exec is called by processes performing an exec */
99 #ifdef CONFIG_SMP
100 extern void sched_exec(void);
101 #else
102 #define sched_exec()   {}
103 #endif
104 
get_task_struct(struct task_struct * t)105 static inline struct task_struct *get_task_struct(struct task_struct *t)
106 {
107 	refcount_inc(&t->usage);
108 	return t;
109 }
110 
111 extern void __put_task_struct(struct task_struct *t);
112 
put_task_struct(struct task_struct * t)113 static inline void put_task_struct(struct task_struct *t)
114 {
115 	if (refcount_dec_and_test(&t->usage))
116 		__put_task_struct(t);
117 }
118 
put_task_struct_many(struct task_struct * t,int nr)119 static inline void put_task_struct_many(struct task_struct *t, int nr)
120 {
121 	if (refcount_sub_and_test(nr, &t->usage))
122 		__put_task_struct(t);
123 }
124 
125 void put_task_struct_rcu_user(struct task_struct *task);
126 
127 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
128 extern int arch_task_struct_size __read_mostly;
129 #else
130 # define arch_task_struct_size (sizeof(struct task_struct))
131 #endif
132 
133 #ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
134 /*
135  * If an architecture has not declared a thread_struct whitelist we
136  * must assume something there may need to be copied to userspace.
137  */
arch_thread_struct_whitelist(unsigned long * offset,unsigned long * size)138 static inline void arch_thread_struct_whitelist(unsigned long *offset,
139 						unsigned long *size)
140 {
141 	*offset = 0;
142 	/* Handle dynamically sized thread_struct. */
143 	*size = arch_task_struct_size - offsetof(struct task_struct, thread);
144 }
145 #endif
146 
147 #ifdef CONFIG_VMAP_STACK
task_stack_vm_area(const struct task_struct * t)148 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
149 {
150 	return t->stack_vm_area;
151 }
152 #else
task_stack_vm_area(const struct task_struct * t)153 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
154 {
155 	return NULL;
156 }
157 #endif
158 
159 /*
160  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
161  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
162  * pins the final release of task.io_context.  Also protects ->cpuset and
163  * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
164  *
165  * Nests both inside and outside of read_lock(&tasklist_lock).
166  * It must not be nested with write_lock_irq(&tasklist_lock),
167  * neither inside nor outside.
168  */
task_lock(struct task_struct * p)169 static inline void task_lock(struct task_struct *p)
170 {
171 	spin_lock(&p->alloc_lock);
172 }
173 
task_unlock(struct task_struct * p)174 static inline void task_unlock(struct task_struct *p)
175 {
176 	spin_unlock(&p->alloc_lock);
177 }
178 
179 #endif /* _LINUX_SCHED_TASK_H */
180