62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/sched.h> /* current and everything */
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#include <linux/kernel.h> /* printk() */
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#include <linux/fs.h> /* everything... */
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#include <linux/types.h> /* size_t */
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#include <linux/completion.h>
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MODULE_LICENSE("Dual BSD/GPL");
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static int complete_major = 0;
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DECLARE_COMPLETION(comp);
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ssize_t complete_read (struct file *filp, char __user *buf, size_t count, loff_t *pos)
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{
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printk(KERN_DEBUG "process %i (%s) going to sleep\n",
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current->pid, current->comm);
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wait_for_completion(&comp);
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printk(KERN_DEBUG "awoken %i (%s)\n", current->pid, current->comm);
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return 0; /* EOF */
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}
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ssize_t complete_write (struct file *filp, const char __user *buf, size_t count,
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loff_t *pos)
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{
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printk(KERN_DEBUG "process %i (%s) awakening the readers...\n",
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current->pid, current->comm);
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complete(&comp);
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return count; /* succeed, to avoid retrial */
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}
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struct file_operations complete_fops = {
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.owner = THIS_MODULE,
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.read = complete_read,
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.write = complete_write,
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};
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int complete_init(void)
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{
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int result;
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printk("hello ni hao\n");
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result = register_chrdev(complete_major, "complete", &complete_fops);
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if (result < 0)
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return result;
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if (complete_major == 0)
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complete_major = result; /* dynamic */
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return 0;
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}
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void complete_cleanup(void)
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{
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unregister_chrdev(complete_major, "complete");
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}
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module_init(complete_init);
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module_exit(complete_cleanup);
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