Can't access task_struct structure from another header file in kernel code

Asked Sep 08 '20 at 17:30

Active Sep 08 '20 at 17:32

Viewed 51 times

I'm trying to access a structure within my module in kernel code, the struct I want access to is task_struct which defined in the <linux/sched.h> header file. And then use current->parent for example, I tried to access the struct inside the init_module function.

I get one warning and one error

error: function declaration isn’t a prototype [-Werror=strict-prototypes]
struct task_struct *current;

warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
struct task_struct *current;

#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h>

MODULE_LICENSE("GPL");

static int hello_init(void)
{
    printk(KERN_ALERT "My-Module: Hello, World\n");
    struct task_struct *current;
    return 0;
}

static void hello_exit(void)
{
    printk(KERN_ALERT "My-Module: Goodbye, cruel world.\n");
}

module_init(hello_init);
module_exit(hello_exit);
// gcc

edited Sep 08 '20 at 17:32

John Kugelman

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asked Sep 08 '20 at 17:30

Dudu Faruk

The name you use for your variable - `current` - is already used for a macro. You need to choose another name for your variable. – Tsyvarev Sep 08 '20 at 17:36
@Tsyvarev Thanks, That solved my problem, but I still get the same warning. Do you have an idea? – Dudu Faruk Sep 08 '20 at 17:39
@Tsyvarev Oh no matter, I don't get any warnings now. – Dudu Faruk Sep 08 '20 at 17:39
@Tsyvarev No matter, I still get this warning. – Dudu Faruk Sep 08 '20 at 17:41
The warning is easy googled, see e.g. that question: https://stackoverflow.com/questions/42262965/warning-iso-c90-forbids-mixing-declarations-and-code-wdeclaration-after-state. – Tsyvarev Sep 08 '20 at 17:54

Can't access task_struct structure from another header file in kernel code

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