Threads in the Linux kernel create interfaces

Describes the kernel interface functions that some kernels provide to us for creating threads in the kernel.

In fact, in the Linux kernel, whether it is a process or a thread, it is represented by a struct task_struct struct.

function to create a kernel thread:

struct task_struct * kthread_create (int (*THREADFN) (void *data),

void *data,

const char namefmt[]);

THREADFN: The function entity that is going to run;

Data: Arguments passed to the function that will be run;

NAMEFMT: Is the name of the thread that was created;

Note: Threads created with the Kthread_create () interface are not run immediately, but instead are placed in the waiting queue. If you want the created thread to run immediately, use the wake_up_process (struct task_struct *task) function to wake up the created thread immediately.

Used to stop a kernel thread:

int kthread_stop (struct task_struct *kthread)

Return value: If this kthread thread is not awakened by Wake_up_process () after the creation of the Ktreadh_create () function, then the Kthread_stop () function is called to stop the thread, A-EINTR error code is returned.

Used to create a thread that runs immediately:

struct task_struct *kthread_run (int (*KTHREADFN) (void *data),

void *data,

const char namefmt[]);

Essentially, the Kthread_run () function is actually a macro definition:

#define KTHREAD_RUN (int (*KTHREADFN) (void *data), \

void *data, \

const char namefmt[]) \

({ \

struct Task_struct *kthread = kthread_create (kthread, data, namefmt[]); \

if (!is_err (kthread)) \

Wake_up_process (Kthread); \

Kthread; \

})

so the return value of the Kthread_run () function: The address of the successful return thread;

Failed to return error address;

A function to determine whether a thread currently in the kernel is still running:

int kthread_should_stop (void)

the Kthread_should_stop () function returns 0 if one of the current threads continues to run in the kernel;

If the current thread is somewhere in the kernel by using kthread_stop (struct task_struct *)

And is stopped, the Kthread_should_stop () function returns 1 immediately.

struct task_struct *kthread_create (int (*KTHREADFN) (void *data),

void *data,

const char namefmt[]);

struct task_struct *kthread_run (int (*KTHREADFN) (void *data),

void *data,

const char namefmt[]);

int kthread_stop (struct task_struct *kthread);

int kthread_should_stop (void);

The functions provided by the kernel for thread creation and thread stop are located in the <linux/kthread.h> header file;

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Threads in the Linux kernel create interfaces