KTHREAD(9) | Kernel Developer's Manual | KTHREAD(9)

# NAME

`kthread_create`, `kthread_exit`, `kthread_create_deferred` — kernel threads

# SYNOPSIS

`#include <sys/kthread.h>`

int
`kthread_create`(void (*func)(void *), void *arg, struct proc **newpp, const char *name);

void
`kthread_exit`(int ecode);

void
`kthread_create_deferred`(void (*func)(void *), void *arg);

# DESCRIPTION

Kernel threads are system light-weight processes: cloned from process 0 (the swapper), sharing its memory map and limits, but with a copy of its file descriptor table. They don't receive broadcast nor group signals and they can't be swapped.

Any process can call `kthread_create`() to create a kernel thread. The new process starts up executing func with argument arg. If newpp is not `NULL`, it is filled with the address of the new process. name is used to name the process.

A kernel thread will terminate by calling `kthread_exit`(), with exit code ecode.

Since the system has to be up and running for creating new processes, device drivers that want to create kernel threads early (e.g., at attach time) may use `kthread_create_deferred`() instead. The system will call back the function func with argument arg when it can create threads, so it is up to func to call `kthread_create`() at that point.

# RETURN VALUES

Upon successful completion, `kthread_create`() returns 0. Otherwise, the following error values are returned:

[`EAGAIN`]
  The limit on the total number of system processes would be exceeded.

# SEE ALSO

fork1(9)

# BUGS

There is currently no way to use ecode to any sensible purpose from `kthread_exit`().

November 18, 2013 | Debian