向user_struct添加另一个字段 [英] add another field to user_struct

问题描述

我想在文件linux-source/kernel/user.c中向user_struct添加新字段(以存储该用户的就绪进程数)

I want to add new field ( to store number of ready process of this user ) to user_struct in file linux-source/kernel/user.c

struct user_struct {
    atomic_t ready_processes; /* I add this field */
    /* not important fields */
}

在哪里正确初始化此字段?

where to initialize this field correctly ?

推荐答案

为了向user_struct添加一个新字段，您需要做三件事:

In order to add a new field to user_struct, you need to do 3 things:

1. user_struct的定义在文件sched.h(include/linux/sched.h)中
   您应该将字段添加到该struct.

1. Definition of user_struct is in file sched.h(include/linux/sched.h)
   You should add your field in that struct.

struct user_struct {
    atomic_t ready_processes; /* I added this line! */
    /*Other fields*/
};

在user.c(内核/user.c)第51行中，全局为root_user实例化了user_struct.在此处为您的字段赋值.

In user.c (kernel/user.c) line 51, user_struct is instantiated for root_user globally. Give your field a value here.

struct user_struct root_user = {
    .ready_processes = ATOMIC_INIT(1), /* I added this line! */
    .__count    = ATOMIC_INIT(2),
    .processes  = ATOMIC_INIT(1),
    .files      = ATOMIC_INIT(0),
    .sigpending = ATOMIC_INIT(0),
    .locked_shm     = 0,
    .user_ns    = &init_user_ns,    
};

您已经完成了为root用户初始化字段的操作，但还应该为其他用户初始化字段.
为此，请在user.c中转到函数alloc_uid，在该函数中分配并初始化新用户.例如，您看到有一行atomic_set(&new->__count, 1);初始化了__count.在此旁边添加您的初始化代码.

You're done with initializing your field for root user but you should also initialize it for other users.
For this aim, in user.c, go to the function alloc_uid where new users get allocated and initialized. For example you see there's a line atomic_set(&new->__count, 1); that initializes __count. Add your initialization code beside this.

atomic_set(&new->__count, 1);
atomic_set(&new->ready_processes, 1); /* I added this line! */

注意:它在Linux 2.6.32.62中工作.我不确定其他版本，但我认为应该没什么不同.

NOTE: It works in linux 2.6.32.62. I'm not sure about other versions but I think it shouldn't be very different.

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