c - 在 linux 中添加系统调用时出现 'ímplicit declaration of function' 错误

Question

我正在尝试添加一个新的系统调用，以显示有关系统中当前正在运行的进程的一些信息。我创建了一个名为 proc_info_struct 的新结构，其中包含我要显示的部分进程信息。这里是procinfo.h头文件中定义的proc_info_struct代码

#include <linux/types.h>
struct proc_info_struct
{
    pid_t pid;
    pid_t parn_pid;
    pid_t gid;
    unsigned long user_time;
    unsigned long sys_time;
    long state;
    unsigned long long sched_avg_running;
    unsigned int time_slice;
    unsigned int policy;
    unsigned long num_cxs;

    int num_children;
    char* prog;
};

在系统调用方法(如下所示)中，我尝试使用 this 使用 signal.h 中定义的 kill() 函数来检查指定的进程是否存在。链接作为引用。这是我用来获取进程信息的代码:

#include <linux/procinfo.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/linkage.h>
#include <linux/kernel.h>
#include <asm/uaccess.h>
#include <asm-generic/current.h>
#include <linux/signal.h>

void fill_proc_info(struct proc_info_struct *proc_info, struct task_struct *task)
{
    int num_ch = 0;
    struct list_head* list;
    proc_info->pid = task->pid;
    proc_info->parn_pid = (task->parent)->pid;
    proc_info->gid = task->tgid;
    proc_info->user_time = task->utime;
    proc_info->sys_time = task->stime;
    proc_info->state = task->state;
    proc_info->sched_avg_running = task->cputime_expires.sum_exec_runtime; //average scheduled running time;
    proc_info->policy = task->policy;
    proc_info->time_slice = task->rt.time_slice;
    proc_info->num_cxs = (task->nvcsw) + (task->nivcsw); //number of context switches(both voluntary and involuntary)

    list_for_each(list, &task->children){
        num_ch++;
    }
    proc_info->num_children = num_ch;
    proc_info->prog = task->comm;
}



asmlinkage long sys_getprocinfo(pid_t pid, struct proc_info_struct *proc)
{
    struct task_struct *task;
    struct proc_info_struct *proc_info;

    if(pid)
    {
        //current process
        task = get_current();
        fill_proc_info(proc_info, task);

    }

    else{
        int exists = 0;//checks whether a process exists or not
        for_each_process(task){
        if(task->pid = pid){
            exists = 1;
        }
    }
    if(exists){
        //task = find_task_by_vpid(pid);  we don't need this line now since the task has now been set in for_each_process

         fill_proc_info(proc_info, task);
    }

    else{
        printk("Process doesn't exist");
        return -ESRCH:
    }

    }
    if (copy_to_user(proc, proc_info, sizeof(proc_info)))
        return -EFAULT;
    return 1;

}

当我尝试使用 make 构建内核时出现以下错误

如上所示，我在以下行中包含了 signal.h header :

#include <linux/signal.h>

我在这里错过了什么？有什么替代方法可以通过使用其 pid 而不是 kill 函数来检查系统中是否存在给定进程？

编辑:根据答案中的建议，我将 kill 函数调用替换为 for_each_process 宏。现在编译成功了。我写了一个测试代码来测试系统调用。当我给出一个不存在的 pid 时，系统调用通过在内核日志中显示“进程不存在”来正常工作。但是，当我提供现有代码时，它会在内核日志中引发显示错误:

BUG: unable to handle kernel NULL pointer dereference at (null)

测试代码

int main()
    {
        struct proc_info_struct *proc_info;
        pid_t pid = 0; //I tried 
        /;

        syscall(314, pid, &proc_info);

        printf("Pid: %ld\nParent: %ld\nGid:%ld\nUtime: %lu\nSysTime: 
            %d\nState: %lu\n,Time_Slice: %d\nPolicy: %d\nNum_CXS: %lu\nNumChild: 
            %d\nProg: %s\n",proc_info->pid, proc_info->parn_pid, proc_info->gid, 
            proc_info->user_time, proc_info->sys_time, proc_info->state, proc_info->time_slice, 
            proc_info->policy, proc_info->num_cxs, proc_info->num_children, proc_info->prog);

        return 0;
    }

Answer 1

齐瓦列夫说得对。 Linux 内核不包含 kill。但它包含 sys_kill .

另外，你可以看我的test project .在那里你可以找到 affl_kill_process()终止进程的函数。