[Linux Device Driver (Third edition)] -- high-speed cache

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• Helloworld. c
• Makefile
• Create a device Node
• Load
• Test
• Uninstall

[Linux Device Driver (Third edition)] ---- high-speed cache helloworld. c

#include <linux/init.h>#include <linux/module.h>#include <linux/moduleparam.h>#include <linux/fs.h>//file_operations, file#include <linux/kernel.h>#include <linux/slab.h>#include <linux/errno.h>#include <linux/types.h>#include <linux/fcntl.h>#include <linux/aio.h>#include <linux/cdev.h>//cdev#include <asm/uaccess.h>//copy_to_user & copy_from_user#include <linux/proc_fs.h>//proc#include <linux/ioctl.h>//ioctlMODULE_LICENSE("Dual BSD/GPL");#define SCULL_QUANTUM 4000#define SCULL_QSET 1000#define SCULL_IOC_MAGIC 'k'#define SCULL_IOC_MAXNR 14#define SCULL_IOCRESET_IO(SCULL_IOC_MAGIC, 0)#define SCULL_IOCSQUANTUM_IOW(SCULL_IOC_MAGIC, 1, int)#define SCULL_IOCSQSET_IOW(SCULL_IOC_MAGIC, 2, int)#define SCULL_IOCTQUANTUM_IO(SCULL_IOC_MAGIC, 3)#define SCULL_IOCTQSET_IO(SCULL_IOC_MAGIC, 4)#define SCULL_IOCGQUANTUM_IOR(SCULL_IOC_MAGIC, 5, int)#define SCULL_IOCGQSET_IOR(SCULL_IOC_MAGIC, 6, int)#define SCULL_IOCQQUANTUM_IO(SCULL_IOC_MAGIC, 7)#define SCULL_IOCQQSET_IO(SCULL_IOC_MAGIC, 8)#define SCULL_IOCXQUANTUM_IOWR(SCULL_IOC_MAGIC, 9, int)#define SCULL_IOCXQSET_IOWR(SCULL_IOC_MAGIC, 10, int)#define SCULL_QUANTUM_IO(SCULL_IOC_MAGIC, 11)#define SCULL_IOCHQSET _IO(SCULL_IOC_MAGIC, 12)int scull_major = 250;int scull_minor = 0;int scull_nr_devs = 4;int scull_quantum = 4000;int scull_qset = 1000;module_param(scull_major, int, S_IRUGO);module_param(scull_minor, int, S_IRUGO);module_param(scull_nr_devs, int, S_IRUGO);module_param(scull_quantum, int, S_IRUGO);module_param(scull_qset, int, S_IRUGO);struct kmem_cache *scullc_cache;struct scull_qset {void **data;struct scull_qset *next;};struct scull_dev{struct scull_qset *data;int quantum;int qset;unsigned long size;unsigned int access_key;struct semaphore sem;struct cdev cdev;};struct scull_dev *scull_devices;int scull_read_procmem(char *buf, char **start, off_t offset, int count, int *eof, void *data){int len = 0;len += sprintf(buf + len, "Proc Test!\n");eof = -1;return len;}static void scull_create_proc(void){create_proc_read_entry("scullmem", 0, NULL, scull_read_procmem, NULL);}static void scull_remove_proc(void){remove_proc_entry("scullmem", NULL);}int scull_trim(struct scull_dev *dev){struct scull_qset *next, *dptr;int qset = dev->qset;int i;for(dptr = dev->data; dptr; dptr = next){if(dptr->data){for(i = 0; i < qset; i++)if(dptr->data[i])kmem_cache_free(scullc_cache, dptr->data[i]);kfree(dptr->data);dptr->data = NULL;}next = dptr->next;if(dptr != dev)kfree(dptr);}dev->size = 0;dev->quantum = scull_quantum;dev->qset = scull_qset;dev->data = NULL;return 0;}int scull_open(struct inode *inode, struct file *filp){struct scull_dev *dev;dev = container_of(inode->i_cdev, struct scull_dev, cdev);filp->private_data = dev;if(filp->f_flags & O_ACCMODE == O_WRONLY){scull_trim(dev);}return 0;}int scull_release(struct inode *inode, struct file *filp){return 0;}struct scull_qset *scull_follow(struct scull_dev *dev, int n){struct scull_qset *qs = dev->data;if(!qs){qs = dev->data = kmalloc(sizeof(struct scull_qset), GFP_KERNEL);if(qs == NULL)return NULL;memset(qs, 0, sizeof(struct scull_qset));}while(n--){if(!qs->next){qs->next = kmalloc(sizeof(struct scull_qset), GFP_KERNEL);if(qs->next == NULL)return NULL;memset(qs->next, 0, sizeof(struct scull_qset));}qs = qs->next;continue;}return qs;}ssize_t scull_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos){printk(KERN_NOTICE "Enter scull_read\n");struct scull_dev *dev = filp->private_data;struct scull_qset *dptr;int quantum = dev->quantum;int qset = dev->qset;int itemsize = quantum * qset;int item, s_pos, q_pos, rest;ssize_t retval = 0;if(down_interruptible(&dev->sem))return -ERESTARTSYS;if(*f_pos >= dev->size)goto out;if(*f_pos + count > dev->size)count = dev->size - *f_pos;item = (long)*f_pos / itemsize;rest = (long)*f_pos % itemsize;s_pos = rest / quantum;q_pos = rest % quantum;dptr = scull_follow(dev, item);if(dptr == NULL || !dptr->data || !dptr->data[s_pos])goto out;if(count > quantum - q_pos)count = quantum - q_pos;if(copy_to_user(buf, dptr->data[s_pos] + q_pos, count)){retval = -EFAULT;goto out;}*f_pos += count;retval = count;out:up(&dev->sem);return retval;}ssize_t scull_write(struct file *filp, char __user *buf, size_t count, loff_t *f_pos){printk(KERN_NOTICE "Enter scull_write\n");struct scull_dev *dev = filp->private_data;struct scull_qset *dptr;int quantum = dev->quantum;int qset = dev->qset;int itemsize = quantum * qset;int item, s_pos, q_pos, rest;ssize_t retval = -ENOMEM;if(down_interruptible(&dev->sem))return -ERESTARTSYS;item = (long)*f_pos / itemsize;rest = (long)*f_pos % itemsize;s_pos = rest / quantum;q_pos = rest % quantum;dptr = scull_follow(dev, item);if(dptr == NULL)goto out;if(!dptr->data){dptr->data = kmalloc(qset * sizeof(char *), GFP_KERNEL);if(!dptr->data)goto out;memset(dptr->data, 0, qset * sizeof(char *));}if(!dptr->data[s_pos]){//dptr->data[s_pos] = kmalloc(quantum, GFP_KERNEL);dptr->data[s_pos] = kmem_cache_alloc(scullc_cache, GFP_KERNEL);if(!dptr->data[s_pos])goto out;memset(dptr->data[s_pos], 0, scull_quantum);}if(count > quantum - q_pos)count = quantum - q_pos;if(copy_from_user(dptr->data[s_pos] + q_pos, buf,  count)){retval = -EFAULT;goto out;}*f_pos += count;retval = count;if(dev->size < *f_pos)dev->size = *f_pos;out:up(&dev->sem);return retval;}int scull_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg){int err = 0, tmp;int retval = 0;if(_IOC_TYPE(cmd) != SCULL_IOC_MAGIC)return -ENOTTY;if(_IOC_NR(cmd) > SCULL_IOC_MAXNR)return -ENOTTY;if(_IOC_DIR(cmd) & _IOC_READ)err = !access_ok(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd));else if(_IOC_DIR(cmd) & _IOC_WRITE)err = !access_ok(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd));if(err)return -EFAULT;switch(cmd){case SCULL_IOCRESET:scull_quantum = SCULL_QUANTUM;scull_qset = SCULL_QSET;break;case SCULL_IOCSQUANTUM:retval = __get_user(scull_quantum, (int __user *)arg);break;case SCULL_IOCTQUANTUM:scull_quantum = arg;break;case SCULL_IOCGQUANTUM:retval = __put_user(scull_quantum, (int __user *)arg);break;case SCULL_IOCQQUANTUM:return scull_quantum;case SCULL_IOCXQUANTUM:tmp = scull_quantum;retval = __get_user(scull_quantum, (int __user *)arg);if(retval == 0)retval = __put_user(tmp, (int __user *)arg);break;case SCULL_QUANTUM:tmp = scull_quantum;scull_quantum = arg;return tmp;case SCULL_IOCSQSET:retval = __get_user(scull_qset, (int __user *)arg);break;case SCULL_IOCTQSET:scull_qset = arg;break;case SCULL_IOCGQSET:retval = __put_user(scull_qset, (int __user *)arg);break;case SCULL_IOCQQSET:return scull_qset;case SCULL_IOCXQSET:tmp = scull_qset;retval = __get_user(scull_qset, (int __user *)arg);if(retval == 0)retval = put_user(tmp, (int __user *)arg);break;case SCULL_IOCHQSET:tmp = scull_qset;scull_qset = arg;return tmp;}}struct file_operations scull_fops = {.owner = THIS_MODULE,.open = scull_open,.release = scull_release,.read = scull_read,.write = scull_write,.ioctl = scull_ioctl,};static void scull_setup_cdev(struct scull_dev *dev, int index){int err, devno = MKDEV(scull_major, scull_minor + index);cdev_init(&dev->cdev, &scull_fops);dev->cdev.owner = THIS_MODULE;err = cdev_add(&dev->cdev, devno, 1);if(err)printk(KERN_NOTICE "Error %d adding scull%d", err, index);}static void scull_cleanup_module(void){printk(KERN_ALERT "Goodbye,world!\n");int i;dev_t devno = MKDEV(scull_major, scull_minor);if(scull_devices){for(i = 0; i < scull_nr_devs; i++){scull_trim(scull_devices + i);cdev_del(&scull_devices[i].cdev);}kfree(scull_devices);}if(scullc_cache)kmem_cache_destroy(scullc_cache);unregister_chrdev_region(devno, scull_nr_devs);scull_remove_proc();}static int __init scull_init_module(void){printk(KERN_ALERT "Hello, World!\n");int result, i;dev_t dev = 0;if(scull_major){dev = MKDEV(scull_major, scull_minor);result = register_chrdev_region(dev, scull_nr_devs, "scull");}else{result = alloc_chrdev_region(&dev, scull_major, scull_nr_devs, "scull");scull_major = MAJOR(dev);}if(result < 0){printk(KERN_WARNING "scull:can't get major %d\n", scull_major);return result;}scull_devices = kmalloc(scull_nr_devs * sizeof(struct scull_dev), GFP_KERNEL);if(!scull_devices){result = -ENOMEM;goto fail;}memset(scull_devices, 0, scull_nr_devs * sizeof(struct scull_dev));for(i = 0; i < scull_nr_devs; i++){scull_devices[i].quantum = scull_quantum;scull_devices[i].qset = scull_qset;init_MUTEX(&scull_devices[i].sem);scull_setup_cdev(&scull_devices[i], i);}printk(KERN_ALERT "kmem_cache_create before!\n");scullc_cache = kmem_cache_create("scullc", scull_quantum,0, SLAB_HWCACHE_ALIGN, NULL);printk(KERN_ALERT "kmem_cache_create after!\n");if(!scullc_cache){scull_cleanup_module();return -ENOMEM;}scull_create_proc();return 0;fail:scull_cleanup_module();return result;}module_init(scull_init_module);module_exit(scull_cleanup_module);

Makefile

obj-m:= HelloWorld.omodules-objs:= HelloWorld.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

Create a device Node

mknod /dev/scull c 250 0

Load

insmod scull.ko

Test

echo "Test" > /dev/scullcat /dev/scull

Output:

Test

Uninstall

rmmod scull