在线程库中使用 getcontext() 出现分段错误 [英] Segmentation Fault using getcontext() in thread library

问题描述

我正在尝试使用系统调用(例如获取上下文、交换上下文等)在 C 中实现用户级线程库

I am trying to implement a user level thread library in C using systems calls such as get context, swap context , etc

我有一个看起来像这样的线程控制块:

I have a thread control block that looks like this :

struct tcb {
    int thread_id;
    int thread_pri;
    ucontext_t *thread_context;
    struct tcb *next;
}

我有一个名为 init() 的函数，它看起来像这样:

And I have a function called init() that looks like this:

void t_init()
{
  tcb *tmp;
  tmp = malloc(sizeof(tcb));

  getcontext(tmp->thread_context);    /* let tmp be the context of main() */
 running_head = tmp;
}

我使用了 gdb，并且在运行时在 getcontext(tmp->thread_context) 函数中遇到了分段错误.

I used gdb and I got a segmentation fault during runtime at the getcontext(tmp->thread_context) function.

我已阅读 getcontext() 的手册页，但不确定为什么这会向我返回分段错误！

I have read the man pages for getcontext() but am unsure as to why this is returning a segmentation fault to me!

请问有什么建议吗?

推荐答案

您还没有为 thread_context 分配任何空间，请尝试

You haven't allocated any space for thread_context, try

void t_init()
{
    struct tcb *tmp;
    tmp = malloc(sizeof(struct tcb));
    if (!tmp)
        return -1;

    memset(&tmp, 0, sizeof(struct tcb));
    tmp->thread_context = malloc(sizeof(ucontext_t));
    if (!tmp->thread_context)
        return -1;

    getcontext(tmp->thread_context);
}

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