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
15 struct task_struct;
16 struct rusage;
17 union thread_union;
18 struct css_set;
19
20 /* All the bits taken by the old clone syscall. */
21 #define CLONE_LEGACY_FLAGS 0xffffffffULL
22
23 struct 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 unsigned int kill_seq;
47 };
48
49 /*
50 * This serializes "schedule()" and also protects
51 * the run-queue from deletions/modifications (but
52 * _adding_ to the beginning of the run-queue has
53 * a separate lock).
54 */
55 extern rwlock_t tasklist_lock;
56 extern spinlock_t mmlist_lock;
57
58 extern union thread_union init_thread_union;
59 extern struct task_struct init_task;
60 #ifdef CONFIG_GKI_DYNAMIC_TASK_STRUCT_SIZE
61 extern u64 vendor_data_pad[CONFIG_GKI_TASK_STRUCT_VENDOR_SIZE_MAX / sizeof(u64)];
62 #endif
63
64 extern int lockdep_tasklist_lock_is_held(void);
65
66 extern asmlinkage void schedule_tail(struct task_struct *prev);
67 extern void init_idle(struct task_struct *idle, int cpu);
68
69 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
70 extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
71 extern void sched_cancel_fork(struct task_struct *p);
72 extern void sched_post_fork(struct task_struct *p);
73 extern void sched_dead(struct task_struct *p);
74
75 void __noreturn do_task_dead(void);
76 void __noreturn make_task_dead(int signr);
77
78 extern void mm_cache_init(void);
79 extern void proc_caches_init(void);
80
81 extern void fork_init(void);
82
83 extern void release_task(struct task_struct * p);
84
85 extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
86
87 extern void flush_thread(void);
88
89 #ifdef CONFIG_HAVE_EXIT_THREAD
90 extern void exit_thread(struct task_struct *tsk);
91 #else
exit_thread(struct task_struct * tsk)92 static inline void exit_thread(struct task_struct *tsk)
93 {
94 }
95 #endif
96 extern __noreturn void do_group_exit(int);
97
98 extern void exit_files(struct task_struct *);
99 extern void exit_itimers(struct task_struct *);
100
101 extern pid_t kernel_clone(struct kernel_clone_args *kargs);
102 struct task_struct *copy_process(struct pid *pid, int trace, int node,
103 struct kernel_clone_args *args);
104 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
105 struct task_struct *fork_idle(int);
106 extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
107 unsigned long flags);
108 extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
109 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
110 int kernel_wait(pid_t pid, int *stat);
111
112 extern void free_task(struct task_struct *tsk);
113
114 /* sched_exec is called by processes performing an exec */
115 #ifdef CONFIG_SMP
116 extern void sched_exec(void);
117 #else
118 #define sched_exec() {}
119 #endif
120
get_task_struct(struct task_struct * t)121 static inline struct task_struct *get_task_struct(struct task_struct *t)
122 {
123 refcount_inc(&t->usage);
124 return t;
125 }
126
tryget_task_struct(struct task_struct * t)127 static inline struct task_struct *tryget_task_struct(struct task_struct *t)
128 {
129 return refcount_inc_not_zero(&t->usage) ? t : NULL;
130 }
131
132 extern void __put_task_struct(struct task_struct *t);
133 extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
134
put_task_struct(struct task_struct * t)135 static inline void put_task_struct(struct task_struct *t)
136 {
137 if (!refcount_dec_and_test(&t->usage))
138 return;
139
140 /*
141 * In !RT, it is always safe to call __put_task_struct().
142 * Under RT, we can only call it in preemptible context.
143 */
144 if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
145 static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
146
147 lock_map_acquire_try(&put_task_map);
148 __put_task_struct(t);
149 lock_map_release(&put_task_map);
150 return;
151 }
152
153 /*
154 * under PREEMPT_RT, we can't call put_task_struct
155 * in atomic context because it will indirectly
156 * acquire sleeping locks.
157 *
158 * call_rcu() will schedule delayed_put_task_struct_rcu()
159 * to be called in process context.
160 *
161 * __put_task_struct() is called when
162 * refcount_dec_and_test(&t->usage) succeeds.
163 *
164 * This means that it can't "conflict" with
165 * put_task_struct_rcu_user() which abuses ->rcu the same
166 * way; rcu_users has a reference so task->usage can't be
167 * zero after rcu_users 1 -> 0 transition.
168 *
169 * delayed_free_task() also uses ->rcu, but it is only called
170 * when it fails to fork a process. Therefore, there is no
171 * way it can conflict with put_task_struct().
172 */
173 call_rcu(&t->rcu, __put_task_struct_rcu_cb);
174 }
175
DEFINE_FREE(put_task,struct task_struct *,if (_T)put_task_struct (_T))176 DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
177
178 static inline void put_task_struct_many(struct task_struct *t, int nr)
179 {
180 if (refcount_sub_and_test(nr, &t->usage))
181 __put_task_struct(t);
182 }
183
184 void put_task_struct_rcu_user(struct task_struct *task);
185
186 /* Free all architecture-specific resources held by a thread. */
187 void release_thread(struct task_struct *dead_task);
188
189 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
190 extern int arch_task_struct_size __read_mostly;
191 #else
192 # define arch_task_struct_size (sizeof(struct task_struct))
193 #endif
194
195 #ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
196 /*
197 * If an architecture has not declared a thread_struct whitelist we
198 * must assume something there may need to be copied to userspace.
199 */
arch_thread_struct_whitelist(unsigned long * offset,unsigned long * size)200 static inline void arch_thread_struct_whitelist(unsigned long *offset,
201 unsigned long *size)
202 {
203 *offset = 0;
204 /* Handle dynamically sized thread_struct. */
205 *size = arch_task_struct_size - offsetof(struct task_struct, thread);
206 }
207 #endif
208
209 #ifdef CONFIG_VMAP_STACK
task_stack_vm_area(const struct task_struct * t)210 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
211 {
212 return t->stack_vm_area;
213 }
214 #else
task_stack_vm_area(const struct task_struct * t)215 static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
216 {
217 return NULL;
218 }
219 #endif
220
221 /*
222 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
223 * subscriptions and synchronises with wait4(). Also used in procfs. Also
224 * pins the final release of task.io_context. Also protects ->cpuset and
225 * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
226 *
227 * Nests both inside and outside of read_lock(&tasklist_lock).
228 * It must not be nested with write_lock_irq(&tasklist_lock),
229 * neither inside nor outside.
230 */
task_lock(struct task_struct * p)231 static inline void task_lock(struct task_struct *p)
232 {
233 spin_lock(&p->alloc_lock);
234 }
235
task_unlock(struct task_struct * p)236 static inline void task_unlock(struct task_struct *p)
237 {
238 spin_unlock(&p->alloc_lock);
239 }
240
DEFINE_GUARD(task_lock,struct task_struct *,task_lock (_T),task_unlock (_T))241 DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T))
242
243 #ifdef CONFIG_GKI_DYNAMIC_TASK_STRUCT_SIZE
244 static inline void *android_task_vendor_data(struct task_struct *p)
245 {
246 if (p == &init_task)
247 return &vendor_data_pad[0];
248
249 return p + 1;
250 }
251
android_init_dynamic_vendor_data(struct task_struct * p)252 static inline void android_init_dynamic_vendor_data(struct task_struct *p)
253 {
254 if (arch_task_struct_size > sizeof(struct task_struct))
255 memset((void *)android_task_vendor_data(p), 0x0,
256 arch_task_struct_size - sizeof(struct task_struct));
257 }
258 #else /* !CONFIG_GKI_DYNAMIC_TASK_STRUCT_SIZE */
259 static inline void android_init_dynamic_vendor_data(struct task_struct *p) {}
260 #endif /* CONFIG_GKI_DYNAMIC_TASK_STRUCT_SIZE */
261
262 #endif /* _LINUX_SCHED_TASK_H */
263