1 #include <linux/version.h>
2 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,17))
3 #include <linux/config.h>
6 #if defined(MODVERSIONS)
7 #include <linux/modversions.h>
9 #include <linux/kernel.h>
10 #include <linux/sched.h>
12 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,40))
13 #include <linux/tqueue.h>
15 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,17))
16 #include <linux/devfs_fs_kernel.h>
20 #include <linux/wait.h>
21 #include <linux/signal.h>
22 #include <linux/interrupt.h>
24 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27))
25 #include <asm/semaphore.h>
27 #include <linux/semaphore.h>
30 #include <linux/smp_lock.h>
32 #include "../include/kthread.h"
34 /* private functions */
35 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,40))
36 static void kthread_launcher(void *data)
38 static void kthread_launcher(unsigned long data)
41 kthread_t *kthread = (kthread_t *)data;
43 kernel_thread((int (*)(void *))kthread->function, (void *)kthread, 0);
46 /* public functions */
48 /* create a new kernel thread. Called by the creator. */
49 void start_kthread(void (*func)(kthread_t *), kthread_t *kthread)
51 /* initialize the semaphore:
52 we start with the semaphore locked. The new kernel
53 thread will setup its stuff and unlock it. This
54 control flow (the one that creates the thread) blocks
55 in the down operation below until the thread has reached
58 sema_init(&kthread->startstop_sem, 0);
60 /* store the function to be executed in the data passed to
62 kthread->function=func;
64 /* create the new thread my running a task through keventd */
66 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,40))
68 /* initialize the task queue structure */
70 INIT_LIST_HEAD(&kthread->tq.list);
71 kthread->tq.routine = kthread_launcher;
72 kthread->tq.data = kthread;
74 /* and schedule it for execution */
75 schedule_task(&kthread->tq);
77 /* initialize tasklet */
78 tasklet_init(&kthread->tq, kthread_launcher, (unsigned long)kthread);
79 /* and schedule it for execution */
80 tasklet_schedule(&kthread->tq);
83 /* wait till it has reached the setup_thread routine */
84 down(&kthread->startstop_sem);
87 /* stop a kernel thread. Called by the removing instance */
88 void stop_kthread(kthread_t *kthread)
90 if (kthread->thread == NULL)
92 printk("stop_kthread: killing non existing thread!\n");
96 /* this function needs to be protected with the big
97 kernel lock (lock_kernel()). The lock must be
98 grabbed before changing the terminate
99 flag and released after the down() call. */
102 /* initialize the semaphore. We lock it here, the
103 leave_thread call of the thread to be terminated
104 will unlock it. As soon as we see the semaphore
105 unlocked, we know that the thread has exited.
107 sema_init(&kthread->startstop_sem,0);
109 /* We need to do a memory barrier here to be sure that
110 the flags are visible on all CPUs.
114 /* set flag to request thread termination */
115 kthread->terminate = 1;
117 /* We need to do a memory barrier here to be sure that
118 the flags are visible on all CPUs.
121 kill_proc(kthread->thread->pid, SIGKILL, 1);
123 /* block till thread terminated */
124 down(&kthread->startstop_sem);
126 /* release the big kernel lock */
129 /* now we are sure the thread is in zombie state. We
130 notify keventd to clean the process up.
132 kill_proc(2, SIGCHLD, 1);
136 /* initialize new created thread. Called by the new thread. */
137 void init_kthread(kthread_t *kthread, char *name)
139 /* fill in thread structure */
140 kthread->thread = current;
142 /* initialise termination flag */
143 kthread->terminate = 0;
145 /* initialise wait queue */
146 init_waitqueue_head(&kthread->queue);
148 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,40))
149 /* lock the kernel. A new kernel thread starts without
150 the big kernel lock, regardless of the lock state
151 of the creator (the lock level is *not* inheritated)
156 /* set signal mask to what we want to respond */
157 siginitsetinv(¤t->blocked, sigmask(SIGKILL)|sigmask(SIGINT)|sigmask(SIGTERM));
159 /* set name of this process (max 15 chars + 0 !) */
160 sprintf(current->comm, name);
169 /* tell the creator that we are ready and let him continue */
170 up(&kthread->startstop_sem);
173 /* cleanup of thread. Called by the exiting thread. */
174 void exit_kthread(kthread_t *kthread)
176 /* we are terminating */
178 /* lock the kernel, the exit will unlock it */
180 kthread->thread = NULL;
183 /* notify the stop_kthread() routine that we are terminating. */
184 up(&kthread->startstop_sem);
185 /* the kernel_thread that called clone() does a do_exit here. */
187 /* there is no race here between execution of the "killer" and real termination
188 of the thread (race window between up and do_exit), since both the
189 thread and the "killer" function are running with the kernel lock held.
190 The kernel lock will be freed after the thread exited, so the code
191 is really not executed anymore as soon as the unload functions gets
192 the kernel lock back.
193 The init process may not have made the cleanup of the process here,
194 but the cleanup can be done safely with the module unloaded.