【Linux裝置驅動程式（第三版）】—-完成量completion

 【Linux裝置驅動程式（第三版）】----完成量completion

complete.c

#include <linux/init.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/types.h>#include <linux/fs.h>//file_operations, file#include <linux/completion.h>#include <asm/uaccess.h>//copy_to_user & copy_from_userMODULE_LICENSE("Dual BSD/GPL");#define MEMSIZE 100int complete_major = 250;DECLARE_COMPLETION(comp);unsigned char s[MEMSIZE];ssize_t complete_read(struct file *filp, char __user *buf, size_t size, loff_t *pos){unsigned long p = *pos;unsigned int count = size;int ret = 0;if(p >= MEMSIZE)return 0;if(count > MEMSIZE - p)count = MEMSIZE -p;wait_for_completion(&comp);if(copy_to_user(buf, (void*)(s + p), count)){return -EFAULT;}*pos += count;ret = count;return ret;}ssize_t complete_write(struct file *filp, char __user *buf, size_t size, loff_t *pos){unsigned long p = *pos;unsigned int count = size;int ret = 0;if(p >= MEMSIZE)return 0;if(count > MEMSIZE - p)count = MEMSIZE -p;if(copy_from_user(s + p, buf, count)){return -EFAULT;}*pos += count;ret = count;complete(&comp);return ret;}struct file_operations complete_fops = {.owner = THIS_MODULE,.read = complete_read,.write = complete_write,};int complete_init(void){int result;result = register_chrdev(complete_major, "complete", &complete_fops);if(result < 0)return result;return 0;}void complete_exit(void){unregister_chrdev(complete_major, "complete");}module_init(complete_init);module_exit(complete_exit);

Makefie

obj-m:= complete.omodules-objs:= complete.oKDIR:= /usr/src/linux-headers-2.6.31-14-generic/PWD:= $(shell pwd)default:make -C $(KDIR) M=$(PWD) modulesclean:rm -rf *.ko *.mod.c *.mod.o *.o *.markers *.symvers *.order

建立裝置節點

mknod /dev/complete c 250 0

裝載

insmod complete.ko

測試

cat /dev/complete

此時，讀線程會進入休眠。

 

開啟另一個終端輸入：

echo "Test" > /dev/complete

此時，讀線程運行，並輸出結果：“Test”

 

卸載

rmmod complete