Hi,
Are there any plans to include the following kernel thread abstraction in a
future kernel version? I think it would be very helpful to have something
like that to make driver development easier.
Regards,
Johannes
-----
From: Christoph Hellwig <hch@caldera.de>
To: linux-kernel@vger.kernel.org
Subject: [PATCH] kthread abstraction, take two
Date: Sat, 9 Feb 2002 18:03:05 +0100
This is a new version of the ktread abstraction which incorporates
suggestions by Andi Kleen, Jeff Garzik and Andrew Morton.
The changes are:
- kthread_start now takes a void * for the user-data, so it doesn't
have to be part of struct kthread.
- the main method of struct kthread now returns an integers, if it
is negative, the thread will be stopped.
- kthread_main no more does the scheduling, it has to be done by
the mainloop now.
The API is now:
int kthread_start(struct kthread *kth, void *data)
Startup a new kernel thread as described by 'kth' (details
below). Wait until it has finished initialization.
void kthread_stop(struct kthread *kth)
Stop the kernel thread described by 'kth'. Wait until is
has finished.
int kthread_running(struct kthread *kth)
Return 1 if the kernel thread described by 'kth' is running.
The 'kthread' structure contains all information for this thread.
Two fields _must_ be initialized:
const char *name;
Name of the thread.
int (*main)(struct kthread *, void);
Mainloop of the thread. This loop is repeated until the thread
is stopped. Stopping is done by either kthread_stop or a
negative return value of this method. This routine has to
release the timeslice after finishing! (i.e. call schedule() or
yield()).
Others may be filled out if needed:
int (*init)(struct kthread *, void *);
Initialize thread before the mainloop is called.
void (*cleanup)(struct kthread *, void *);
Cleanup after the mainloop is done.
void *data;
Opaque data for the thread's use
Patch for 2.5.4-pre5 is below.
Christoph
-- diff -uNr -Xdontdiff ../master/linux-2.5.4-pre5/include/linux/kthread.h linux/include/linux/kthread.h --- ../master/linux-2.5.4-pre5/include/linux/kthread.h Thu Jan 1 01:00:00 1970 +++ linux/include/linux/kthread.h Sat Feb 9 17:43:12 2002 @@ -0,0 +1,22 @@ +#ifndef _LINUX_KTHREAD_H +#define _LINUX_KTHREAD_H + +struct task_struct; + +struct kthread { + const char *name; + struct task_struct *task; + struct completion done; +#define KTH_RUNNING 1 +#define KTH_SHUTDOWN 2 + long state; + int (*init)(struct kthread *, void *); + void (*cleanup)(struct kthread *, void *); + int (*main)(struct kthread *, void *); +}; + +extern int kthread_start(struct kthread *, void *); +extern void kthread_stop(struct kthread *); +extern int kthread_running(struct kthread *); + +#endif /* _LINUX_KTHREAD_H */ diff -uNr -Xdontdiff ../master/linux-2.5.4-pre5/kernel/Makefile linux/kernel/Makefile --- ../master/linux-2.5.4-pre5/kernel/Makefile Fri Feb 1 16:27:04 2002 +++ linux/kernel/Makefile Sat Feb 9 17:42:58 2002 @@ -10,12 +10,12 @@ O_TARGET := kernel.o export-objs = signal.o sys.o kmod.o context.o ksyms.o pm.o exec_domain.o \ - printk.o + printk.o kthread.o obj-y = sched.o dma.o fork.o exec_domain.o panic.o printk.o \ module.o exit.o itimer.o info.o time.o softirq.o resource.o \ sysctl.o acct.o capability.o ptrace.o timer.o user.o \ - signal.o sys.o kmod.o context.o + signal.o sys.o kmod.o context.o kthread.o obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += ksyms.o diff -uNr -Xdontdiff ../master/linux-2.5.4-pre5/kernel/kthread.c linux/kernel/kthread.c --- ../master/linux-2.5.4-pre5/kernel/kthread.c Thu Jan 1 01:00:00 1970 +++ linux/kernel/kthread.c Sat Feb 9 17:43:47 2002 @@ -0,0 +1,148 @@ +/* + * Copyright (c) 2002 Christoph Hellwig. + * All rights resered. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/completion.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/signal.h> +#include <linux/smp_lock.h> +#include <linux/spinlock.h> +#include <asm/bitops.h> + +#define KTHREAD_FLAGS \ + (CLONE_FS|CLONE_FILES|CLONE_SIGHAND) + +struct kthread_args { + struct kthread *kth; + void *data; +}; + + +static int kthread_stopped(struct kthread *kth) +{ + struct task_struct *task = kth->task; + unsigned long signr; + siginfo_t info; + + spin_lock_irq(&task->sigmask_lock); + signr = dequeue_signal(&task->blocked, &info); + spin_unlock_irq(&task->sigmask_lock); + + if (signr == SIGKILL && test_bit(KTH_SHUTDOWN, &kth->state)) + return 1; + return 0; +} + +static int kthread_main(void *p) +{ + struct kthread_args *args = p; + struct kthread *kth = args->kth; + void *data = args->data; + + lock_kernel(); + daemonize(); + reparent_to_init(); + strcpy(current->comm, kth->name); + unlock_kernel(); + + kth->task = current; + + spin_lock_irq(¤t->sigmask_lock); + siginitsetinv(¤t->blocked, + sigmask(SIGHUP) | sigmask(SIGKILL) | + sigmask(SIGSTOP) | sigmask(SIGCONT)); + spin_unlock_irq(¤t->sigmask_lock); + + if (kth->init) + kth->init(kth, data); + complete(&kth->done); + + do { + if (kth->main(kth, data) < 0) + break; + } while (!kthread_stopped(kth)); + + if (kth->cleanup) + kth->cleanup(kth, data); + clear_bit(KTH_RUNNING, &kth->state); + complete(&kth->done); + return 0; +} + +/** + * kthread_start - start a new kernel thread + * @kth: kernel thread description + * @data: opaque data for use with the methods + * + * For off a new kernel thread as described by @kth. + */ +int kthread_start(struct kthread *kth, void *data) +{ + struct kthread_args args; + pid_t pid; + + if (!kth->name || !kth->main) + return -EINVAL; + + args.kth = kth; + args.data = data; + + init_completion(&kth->done); + if ((pid = kernel_thread(kthread_main, &args, KTHREAD_FLAGS)) < 0) + return pid; + set_bit(KTH_RUNNING, &kth->state); + wait_for_completion(&kth->done); + return 0; +} + +/** + * kthread_stop - stop a kernel thread + * @kth: kernel thread description + * + * Stop the kernel thread described by @kth. + */ +void kthread_stop(struct kthread *kth) +{ + if (kth->task) { + init_completion(&kth->done); + set_bit(KTH_SHUTDOWN, &kth->state); + send_sig(SIGKILL, kth->task, 1); + wait_for_completion(&kth->done); + kth->task = NULL; + clear_bit(KTH_SHUTDOWN, &kth->state); + } +} + +/** + * kthread_running - check whether a kernel thread is running + * @kth: kernel thread description + * + * Checks whether the kernel thread described by @kth is running. + */ +int kthread_running(struct kthread *kth) +{ + return test_bit(KTH_RUNNING, &kth->state); +} + +EXPORT_SYMBOL(kthread_start); +EXPORT_SYMBOL(kthread_stop); +EXPORT_SYMBOL(kthread_running); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Aug 23 2002 - 22:00:20 EST