FW: Subject: [PATCH] kthread abstraction, take two (or three)

[Loebbert, Johannes]

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 <[e-mail]> 
To:      [e-mail] 
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(&current->sigmask_lock); 
+       siginitsetinv(&current->blocked, 
+                       sigmask(SIGHUP) | sigmask(SIGKILL) | 
+                       sigmask(SIGSTOP) | sigmask(SIGCONT)); 
+       spin_unlock_irq(&current->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);