240 lines
6.6 KiB
C
240 lines
6.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SCHED_TASK_H
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#define _LINUX_SCHED_TASK_H
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/*
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* Interface between the scheduler and various task lifetime (fork()/exit())
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* functionality:
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*/
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#include <linux/rcupdate.h>
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#include <linux/refcount.h>
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#include <linux/sched.h>
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#include <linux/uaccess.h>
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struct task_struct;
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struct rusage;
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union thread_union;
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struct css_set;
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/* All the bits taken by the old clone syscall. */
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#define CLONE_LEGACY_FLAGS 0xffffffffULL
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struct kernel_clone_args {
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u64 flags;
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int __user *pidfd;
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int __user *child_tid;
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int __user *parent_tid;
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const char *name;
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int exit_signal;
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u32 kthread:1;
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u32 io_thread:1;
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u32 user_worker:1;
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u32 no_files:1;
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unsigned long stack;
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unsigned long stack_size;
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unsigned long tls;
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pid_t *set_tid;
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/* Number of elements in *set_tid */
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size_t set_tid_size;
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int cgroup;
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int idle;
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int (*fn)(void *);
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void *fn_arg;
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struct cgroup *cgrp;
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struct css_set *cset;
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};
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/*
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* This serializes "schedule()" and also protects
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* the run-queue from deletions/modifications (but
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* _adding_ to the beginning of the run-queue has
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* a separate lock).
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*/
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extern rwlock_t tasklist_lock;
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extern spinlock_t mmlist_lock;
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extern union thread_union init_thread_union;
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extern struct task_struct init_task;
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extern int lockdep_tasklist_lock_is_held(void);
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extern asmlinkage void schedule_tail(struct task_struct *prev);
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extern void init_idle(struct task_struct *idle, int cpu);
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extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
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extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
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extern void sched_cancel_fork(struct task_struct *p);
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extern void sched_post_fork(struct task_struct *p);
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extern void sched_dead(struct task_struct *p);
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void __noreturn do_task_dead(void);
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void __noreturn make_task_dead(int signr);
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extern void mm_cache_init(void);
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extern void proc_caches_init(void);
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extern void fork_init(void);
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extern void release_task(struct task_struct * p);
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extern int copy_thread(struct task_struct *, const struct kernel_clone_args *);
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extern void flush_thread(void);
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#ifdef CONFIG_HAVE_EXIT_THREAD
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extern void exit_thread(struct task_struct *tsk);
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#else
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static inline void exit_thread(struct task_struct *tsk)
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{
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}
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#endif
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extern __noreturn void do_group_exit(int);
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extern void exit_files(struct task_struct *);
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extern void exit_itimers(struct task_struct *);
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extern pid_t kernel_clone(struct kernel_clone_args *kargs);
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struct task_struct *copy_process(struct pid *pid, int trace, int node,
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struct kernel_clone_args *args);
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struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node);
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struct task_struct *fork_idle(int);
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extern pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
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unsigned long flags);
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extern pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags);
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extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
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int kernel_wait(pid_t pid, int *stat);
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extern void free_task(struct task_struct *tsk);
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/* sched_exec is called by processes performing an exec */
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#ifdef CONFIG_SMP
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extern void sched_exec(void);
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#else
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#define sched_exec() {}
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#endif
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static inline struct task_struct *get_task_struct(struct task_struct *t)
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{
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refcount_inc(&t->usage);
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return t;
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}
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static inline struct task_struct *tryget_task_struct(struct task_struct *t)
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{
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return refcount_inc_not_zero(&t->usage) ? t : NULL;
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}
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extern void __put_task_struct(struct task_struct *t);
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extern void __put_task_struct_rcu_cb(struct rcu_head *rhp);
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static inline void put_task_struct(struct task_struct *t)
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{
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if (!refcount_dec_and_test(&t->usage))
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return;
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/*
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* In !RT, it is always safe to call __put_task_struct().
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* Under RT, we can only call it in preemptible context.
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*/
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if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
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static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
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lock_map_acquire_try(&put_task_map);
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__put_task_struct(t);
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lock_map_release(&put_task_map);
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return;
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}
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/*
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* under PREEMPT_RT, we can't call put_task_struct
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* in atomic context because it will indirectly
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* acquire sleeping locks.
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*
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* call_rcu() will schedule delayed_put_task_struct_rcu()
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* to be called in process context.
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*
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* __put_task_struct() is called when
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* refcount_dec_and_test(&t->usage) succeeds.
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*
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* This means that it can't "conflict" with
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* put_task_struct_rcu_user() which abuses ->rcu the same
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* way; rcu_users has a reference so task->usage can't be
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* zero after rcu_users 1 -> 0 transition.
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*
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* delayed_free_task() also uses ->rcu, but it is only called
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* when it fails to fork a process. Therefore, there is no
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* way it can conflict with put_task_struct().
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*/
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call_rcu(&t->rcu, __put_task_struct_rcu_cb);
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}
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DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
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static inline void put_task_struct_many(struct task_struct *t, int nr)
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{
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if (refcount_sub_and_test(nr, &t->usage))
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__put_task_struct(t);
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}
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void put_task_struct_rcu_user(struct task_struct *task);
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/* Free all architecture-specific resources held by a thread. */
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void release_thread(struct task_struct *dead_task);
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#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
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extern int arch_task_struct_size __read_mostly;
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#else
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# define arch_task_struct_size (sizeof(struct task_struct))
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#endif
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#ifndef CONFIG_HAVE_ARCH_THREAD_STRUCT_WHITELIST
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/*
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* If an architecture has not declared a thread_struct whitelist we
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* must assume something there may need to be copied to userspace.
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*/
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static inline void arch_thread_struct_whitelist(unsigned long *offset,
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unsigned long *size)
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{
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*offset = 0;
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/* Handle dynamically sized thread_struct. */
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*size = arch_task_struct_size - offsetof(struct task_struct, thread);
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}
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#endif
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#ifdef CONFIG_VMAP_STACK
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static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
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{
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return t->stack_vm_area;
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}
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#else
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static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
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{
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return NULL;
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}
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#endif
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/*
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* Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
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* subscriptions and synchronises with wait4(). Also used in procfs. Also
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* pins the final release of task.io_context. Also protects ->cpuset and
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* ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
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*
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* Nests both inside and outside of read_lock(&tasklist_lock).
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* It must not be nested with write_lock_irq(&tasklist_lock),
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* neither inside nor outside.
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*/
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static inline void task_lock(struct task_struct *p)
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{
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spin_lock(&p->alloc_lock);
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}
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static inline void task_unlock(struct task_struct *p)
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{
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spin_unlock(&p->alloc_lock);
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}
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DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T))
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#endif /* _LINUX_SCHED_TASK_H */
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