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 void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs); 67extern void sched_post_fork(struct task_struct *p); 68extern void sched_dead(struct task_struct *p); 69 70void __noreturn do_task_dead(void); 71void __noreturn make_task_dead(int signr); 72 73extern void mm_cache_init(void); 74extern void proc_caches_init(void); 75 76extern void fork_init(void); 77 78extern void release_task(struct task_struct * p); 79 80extern int copy_thread(struct task_struct *, const struct kernel_clone_args *); 81 82extern void flush_thread(void); 83 84#ifdef CONFIG_HAVE_EXIT_THREAD 85extern void exit_thread(struct task_struct *tsk); 86#else 87static inline void exit_thread(struct task_struct *tsk) 88{ 89} 90#endif 91extern __noreturn void do_group_exit(int); 92 93extern void exit_files(struct task_struct *); 94extern void exit_itimers(struct task_struct *); 95 96extern pid_t kernel_clone(struct kernel_clone_args *kargs); 97struct task_struct *copy_process(struct pid *pid, int trace, int node, 98 struct kernel_clone_args *args); 99struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node); 100struct task_struct *fork_idle(int); 101extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name, 102 unsigned long flags); 103extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags); 104extern long kernel_wait4(pid_t, int __user *, int, struct rusage *); 105int kernel_wait(pid_t pid, int *stat); 106 107extern void free_task(struct task_struct *tsk); 108 109/* sched_exec is called by processes performing an exec */ 110#ifdef CONFIG_SMP 111extern void sched_exec(void); 112#else 113#define sched_exec() {} 114#endif 115 116static inline struct task_struct *get_task_struct(struct task_struct *t) 117{ 118 refcount_inc(&t->usage); 119 return t; 120} 121 122extern void __put_task_struct(struct task_struct *t); 123extern void __put_task_struct_rcu_cb(struct rcu_head *rhp); 124 125static inline void put_task_struct(struct task_struct *t) 126{ 127 if (!refcount_dec_and_test(&t->usage)) 128 return; 129 130 /* 131 * In !RT, it is always safe to call __put_task_struct(). 132 * Under RT, we can only call it in preemptible context. 133 */ 134 if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) { 135 static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP); 136 137 lock_map_acquire_try(&put_task_map); 138 __put_task_struct(t); 139 lock_map_release(&put_task_map); 140 return; 141 } 142 143 /* 144 * under PREEMPT_RT, we can't call put_task_struct 145 * in atomic context because it will indirectly 146 * acquire sleeping locks. 147 * 148 * call_rcu() will schedule delayed_put_task_struct_rcu() 149 * to be called in process context. 150 * 151 * __put_task_struct() is called when 152 * refcount_dec_and_test(&t->usage) succeeds. 153 * 154 * This means that it can't "conflict" with 155 * put_task_struct_rcu_user() which abuses ->rcu the same 156 * way; rcu_users has a reference so task->usage can't be 157 * zero after rcu_users 1 -> 0 transition. 158 * 159 * delayed_free_task() also uses ->rcu, but it is only called 160 * when it fails to fork a process. Therefore, there is no 161 * way it can conflict with put_task_struct(). 162 */ 163 call_rcu(&t->rcu, __put_task_struct_rcu_cb); 164} 165 166DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T)) 167 168static inline void put_task_struct_many(struct task_struct *t, int nr) 169{ 170 if (refcount_sub_and_test(nr, &t->usage)) 171 __put_task_struct(t); 172} 173 174void put_task_struct_rcu_user(struct task_struct *task); 175 176/* Free all architecture-specific resources held by a thread. */ 177void release_thread(struct task_struct *dead_task); 178 179#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT 180extern int arch_task_struct_size __read_mostly; 181#else 182# define arch_task_struct_size (sizeof(struct task_struct)) 183#endif 184 185#ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST 186/* 187 * If an architecture has not declared a thread_struct whitelist we 188 * must assume something there may need to be copied to userspace. 189 */ 190static inline void arch_thread_struct_whitelist(unsigned long *offset, 191 unsigned long *size) 192{ 193 *offset = 0; 194 /* Handle dynamically sized thread_struct. */ 195 *size = arch_task_struct_size - offsetof(struct task_struct, thread); 196} 197#endif 198 199#ifdef CONFIG_VMAP_STACK 200static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t) 201{ 202 return t->stack_vm_area; 203} 204#else 205static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t) 206{ 207 return NULL; 208} 209#endif 210 211/* 212 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring 213 * subscriptions and synchronises with wait4(). Also used in procfs. Also 214 * pins the final release of task.io_context. Also protects ->cpuset and 215 * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist. 216 * 217 * Nests both inside and outside of read_lock(&tasklist_lock). 218 * It must not be nested with write_lock_irq(&tasklist_lock), 219 * neither inside nor outside. 220 */ 221static inline void task_lock(struct task_struct *p) 222{ 223 spin_lock(&p->alloc_lock); 224} 225 226static inline void task_unlock(struct task_struct *p) 227{ 228 spin_unlock(&p->alloc_lock); 229} 230 231DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T)) 232 233#endif /* _LINUX_SCHED_TASK_H */ 234