xref: /openbmc/linux/include/linux/sched/task.h (revision fd5e9fccbd504c5179ab57ff695c610bca8809d6)
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 	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 	unsigned int kill_seq;
45 };
46 
47 /*
48  * This serializes "schedule()" and also protects
49  * the run-queue from deletions/modifications (but
50  * _adding_ to the beginning of the run-queue has
51  * a separate lock).
52  */
53 extern rwlock_t tasklist_lock;
54 extern spinlock_t mmlist_lock;
55 
56 extern union thread_union init_thread_union;
57 extern struct task_struct init_task;
58 
59 extern int lockdep_tasklist_lock_is_held(void);
60 
61 extern asmlinkage void schedule_tail(struct task_struct *prev);
62 extern void init_idle(struct task_struct *idle, int cpu);
63 
64 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
65 extern void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
66 extern void sched_post_fork(struct task_struct *p);
67 extern void sched_dead(struct task_struct *p);
68 
69 void __noreturn do_task_dead(void);
70 void __noreturn make_task_dead(int signr);
71 
72 extern void mm_cache_init(void);
73 extern void proc_caches_init(void);
74 
75 extern void fork_init(void);
76 
77 extern void release_task(struct task_struct * p);
78 
79 extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
80 
81 extern void flush_thread(void);
82 
83 #ifdef CONFIG_HAVE_EXIT_THREAD
84 extern void exit_thread(struct task_struct *tsk);
85 #else
exit_thread(struct task_struct * tsk)86 static inline void exit_thread(struct task_struct *tsk)
87 {
88 }
89 #endif
90 extern __noreturn void do_group_exit(int);
91 
92 extern void exit_files(struct task_struct *);
93 extern void exit_itimers(struct task_struct *);
94 
95 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
96 struct task_struct *copy_process(struct pid *pid, int trace, int node,
97 				 struct kernel_clone_args *args);
98 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
99 struct task_struct *fork_idle(int);
100 extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
101 			    unsigned long flags);
102 extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
103 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
104 int kernel_wait(pid_t pid, int *stat);
105 
106 extern void free_task(struct task_struct *tsk);
107 
108 /* sched_exec is called by processes performing an exec */
109 #ifdef CONFIG_SMP
110 extern void sched_exec(void);
111 #else
112 #define sched_exec()   {}
113 #endif
114 
get_task_struct(struct task_struct * t)115 static inline struct task_struct *get_task_struct(struct task_struct *t)
116 {
117 	refcount_inc(&t->usage);
118 	return t;
119 }
120 
121 extern void __put_task_struct(struct task_struct *t);
122 extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
123 
put_task_struct(struct task_struct * t)124 static inline void put_task_struct(struct task_struct *t)
125 {
126 	if (!refcount_dec_and_test(&t->usage))
127 		return;
128 
129 	/*
130 	 * In !RT, it is always safe to call __put_task_struct().
131 	 * Under RT, we can only call it in preemptible context.
132 	 */
133 	if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
134 		static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
135 
136 		lock_map_acquire_try(&put_task_map);
137 		__put_task_struct(t);
138 		lock_map_release(&put_task_map);
139 		return;
140 	}
141 
142 	/*
143 	 * under PREEMPT_RT, we can't call put_task_struct
144 	 * in atomic context because it will indirectly
145 	 * acquire sleeping locks.
146 	 *
147 	 * call_rcu() will schedule delayed_put_task_struct_rcu()
148 	 * to be called in process context.
149 	 *
150 	 * __put_task_struct() is called when
151 	 * refcount_dec_and_test(&t->usage) succeeds.
152 	 *
153 	 * This means that it can't "conflict" with
154 	 * put_task_struct_rcu_user() which abuses ->rcu the same
155 	 * way; rcu_users has a reference so task->usage can't be
156 	 * zero after rcu_users 1 -> 0 transition.
157 	 *
158 	 * delayed_free_task() also uses ->rcu, but it is only called
159 	 * when it fails to fork a process. Therefore, there is no
160 	 * way it can conflict with put_task_struct().
161 	 */
162 	call_rcu(&t->rcu, __put_task_struct_rcu_cb);
163 }
164 
DEFINE_FREE(put_task,struct task_struct *,if (_T)put_task_struct (_T))165 DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
166 
167 static inline void put_task_struct_many(struct task_struct *t, int nr)
168 {
169 	if (refcount_sub_and_test(nr, &t->usage))
170 		__put_task_struct(t);
171 }
172 
173 void put_task_struct_rcu_user(struct task_struct *task);
174 
175 /* Free all architecture-specific resources held by a thread. */
176 void release_thread(struct task_struct *dead_task);
177 
178 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
179 extern int arch_task_struct_size __read_mostly;
180 #else
181 # define arch_task_struct_size (sizeof(struct task_struct))
182 #endif
183 
184 #ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
185 /*
186  * If an architecture has not declared a thread_struct whitelist we
187  * must assume something there may need to be copied to userspace.
188  */
arch_thread_struct_whitelist(unsigned long * offset,unsigned long * size)189 static inline void arch_thread_struct_whitelist(unsigned long *offset,
190 						unsigned long *size)
191 {
192 	*offset = 0;
193 	/* Handle dynamically sized thread_struct. */
194 	*size = arch_task_struct_size - offsetof(struct task_struct, thread);
195 }
196 #endif
197 
198 #ifdef CONFIG_VMAP_STACK
task_stack_vm_area(const struct task_struct * t)199 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
200 {
201 	return t->stack_vm_area;
202 }
203 #else
task_stack_vm_area(const struct task_struct * t)204 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
205 {
206 	return NULL;
207 }
208 #endif
209 
210 /*
211  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
212  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
213  * pins the final release of task.io_context.  Also protects ->cpuset and
214  * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
215  *
216  * Nests both inside and outside of read_lock(&tasklist_lock).
217  * It must not be nested with write_lock_irq(&tasklist_lock),
218  * neither inside nor outside.
219  */
task_lock(struct task_struct * p)220 static inline void task_lock(struct task_struct *p)
221 {
222 	spin_lock(&p->alloc_lock);
223 }
224 
task_unlock(struct task_struct * p)225 static inline void task_unlock(struct task_struct *p)
226 {
227 	spin_unlock(&p->alloc_lock);
228 }
229 
230 #endif /* _LINUX_SCHED_TASK_H */
231