get_robust_list()函数 Unix/Linux

get_robust_list, set_robust_list - 获取/设置强健futexes的清单

内容简介

#include <linux/futex.h> 
#include <syscall.h>

long get_robust_list(int pid, struct robust_list_head **head_ptr, size_t * long set_robust_list(struct robust_list_head *head, size_t len);

描述

The robust futex implementation needs to maintain per-thread lists of robust futexes which are unlocked when the thread exits. These lists are managed in user space, the kernel is only notified about the location of the head of the list.

get_robust_list returns the head of the robust futex list of the thread with TID defined by the pid argument. If pid is 0, the returned head belongs to the current thread.head_ptr is the pointer to the head of the list of robust futexes. The get_robust_listfunction stores the address of the head of the list here. len_ptr is the pointer to the length variable. get_robust_list stores sizeof(**head_ptr) here.

set_robust_list sets the head of the list of robust futexes owned by the current thread to head. len is the size of *head.

返回值

The set_robust_list and get_robust_list functions return zero when the operation is successful, an error code otherwise.

错误

The set_robust_list function fails with EINVAL if the len value does not match the size of structure struct robust_list_head expected by kernel.

The get_robust_list function fails with EPERM if the current process does not have permission to see the robust futex list of the thread with the TID pid, ESRCH if a thread with the TID pid does not exist, or EFAULT if the head of the robust futex list can’t be stored in the space specified by the head argument.

实际应用信息

一个线程只能有一个强大的 futex 清单，因此希望使用该功能的应用程序应该使用的glibc提供强大的互斥体。

系统调用是唯一可用于调试目的，不正常操作所需的。

这两个系统调用是不提供给应用程序的功能，他们可以使用 syscall(3)函数被调用。

另请参阅

futex (2)