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| #include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> /* printk() */ #include <linux/slab.h> /* kmalloc() */ #include <linux/fs.h> /* everything... */ #include <linux/errno.h> /* error codes */ #include <linux/types.h> /* size_t */ #include <linux/fcntl.h> /* O_ACCMODE */ #include <linux/cdev.h> #include <asm/uaccess.h> /* copy_*_user */
MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Hcamael");
int scull_major = 0; int scull_minor = 0; int scull_nr_devs = 4; int scull_quantum = 4000; int scull_qset = 1000;
struct scull_qset { void **data; struct scull_qset *next; };
struct scull_dev { struct scull_qset *data; /* Pointer to first quantum set. */ int quantum; /* The current quantum size. */ int qset; /* The current array size. */ unsigned long size; /* Amount of data stored here. */ unsigned int access_key; /* Used by sculluid and scullpriv. */ struct mutex mutex; /* Mutual exclusion semaphore. */ struct cdev cdev; /* Char device structure. */ };
struct scull_dev *scull_devices; /* allocated in scull_init_module */
/* * Follow the list. */ struct scull_qset *scull_follow(struct scull_dev *dev, int n) { struct scull_qset *qs = dev->data;
/* Allocate the first qset explicitly if need be. */ if (! qs) { qs = dev->data = kmalloc(sizeof(struct scull_qset), GFP_KERNEL); if (qs == NULL) return NULL; memset(qs, 0, sizeof(struct scull_qset)); }
/* Then follow the list. */ 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; }
/* * Data management: read and write. */
ssize_t scull_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) { struct scull_dev *dev = filp->private_data; struct scull_qset *dptr; /* the first listitem */ int quantum = dev->quantum, qset = dev->qset; int itemsize = quantum * qset; /* how many bytes in the listitem */ int item, s_pos, q_pos, rest; ssize_t retval = 0;
if (mutex_lock_interruptible(&dev->mutex)) return -ERESTARTSYS; if (*f_pos >= dev->size) goto out; if (*f_pos + count > dev->size) count = dev->size - *f_pos;
/* Find listitem, qset index, and offset in the quantum */ item = (long)*f_pos / itemsize; rest = (long)*f_pos % itemsize; s_pos = rest / quantum; q_pos = rest % quantum;
/* follow the list up to the right position (defined elsewhere) */ dptr = scull_follow(dev, item);
if (dptr == NULL || !dptr->data || ! dptr->data[s_pos]) goto out; /* don't fill holes */
/* read only up to the end of this quantum */ if (count > quantum - q_pos) count = quantum - q_pos;
if (raw_copy_to_user(buf, dptr->data[s_pos] + q_pos, count)) { retval = -EFAULT; goto out; } *f_pos += count; retval = count;
out: mutex_unlock(&dev->mutex); return retval; }
ssize_t scull_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos) { struct scull_dev *dev = filp->private_data; struct scull_qset *dptr; int quantum = dev->quantum, qset = dev->qset; int itemsize = quantum * qset; int item, s_pos, q_pos, rest; ssize_t retval = -ENOMEM; /* Value used in "goto out" statements. */
if (mutex_lock_interruptible(&dev->mutex)) return -ERESTARTSYS;
/* Find the list item, qset index, and offset in the quantum. */ item = (long)*f_pos / itemsize; rest = (long)*f_pos % itemsize; s_pos = rest / quantum; q_pos = rest % quantum;
/* Follow the list up to the right position. */ 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); if (!dptr->data[s_pos]) goto out; } /* Write only up to the end of this quantum. */ if (count > quantum - q_pos) count = quantum - q_pos;
if (raw_copy_from_user(dptr->data[s_pos]+q_pos, buf, count)) { retval = -EFAULT; goto out; } *f_pos += count; retval = count;
/* Update the size. */ if (dev->size < *f_pos) dev->size = *f_pos;
out: mutex_unlock(&dev->mutex); return retval; }
/* Beginning of the scull device implementation. */
/* * Empty out the scull device; must be called with the device * mutex held. */ int scull_trim(struct scull_dev *dev) { struct scull_qset *next, *dptr; int qset = dev->qset; /* "dev" is not-null */ int i;
for (dptr = dev->data; dptr; dptr = next) { /* all the list items */ if (dptr->data) { for (i = 0; i < qset; i++) kfree(dptr->data[i]); kfree(dptr->data); dptr->data = NULL; } next = dptr->next; kfree(dptr); } dev->size = 0; dev->quantum = scull_quantum; dev->qset = scull_qset; dev->data = NULL; return 0; }
int scull_release(struct inode *inode, struct file *filp) { printk(KERN_DEBUG "process %i (%s) success release minor(%u) file\n", current->pid, current->comm, iminor(inode)); return 0; }
/* * Open and close */
int scull_open(struct inode *inode, struct file *filp) { struct scull_dev *dev; /* device information */
dev = container_of(inode->i_cdev, struct scull_dev, cdev); filp->private_data = dev; /* for other methods */
/* If the device was opened write-only, trim it to a length of 0. */ if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) { if (mutex_lock_interruptible(&dev->mutex)) return -ERESTARTSYS; scull_trim(dev); /* Ignore errors. */ mutex_unlock(&dev->mutex); } printk(KERN_DEBUG "process %i (%s) success open minor(%u) file\n", current->pid, current->comm, iminor(inode)); return 0; }
/* * The "extended" operations -- only seek. */
loff_t scull_llseek(struct file *filp, loff_t off, int whence) { struct scull_dev *dev = filp->private_data; loff_t newpos;
switch(whence) { case 0: /* SEEK_SET */ newpos = off; break;
case 1: /* SEEK_CUR */ newpos = filp->f_pos + off; break;
case 2: /* SEEK_END */ newpos = dev->size + off; break;
default: /* can't happen */ return -EINVAL; } if (newpos < 0) return -EINVAL; filp->f_pos = newpos; return newpos; }
struct file_operations scull_fops = { .owner = THIS_MODULE, .llseek = scull_llseek, .read = scull_read, .write = scull_write, // .unlocked_ioctl = scull_ioctl, .open = scull_open, .release = scull_release, };
/* * Set up the char_dev structure for this device. */ 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; dev->cdev.ops = &scull_fops; err = cdev_add (&dev->cdev, devno, 1); /* Fail gracefully if need be. */ if (err) printk(KERN_NOTICE "Error %d adding scull%d", err, index); else printk(KERN_INFO "scull: %d add success\n", index); }
void scull_cleanup_module(void) { int i; dev_t devno = MKDEV(scull_major, scull_minor);
/* Get rid of our char dev entries. */ 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); }
/* cleanup_module is never called if registering failed. */ unregister_chrdev_region(devno, scull_nr_devs); printk(KERN_INFO "scull: cleanup success\n"); }
int scull_init_module(void) { int result, i; dev_t dev = 0;
/* * Get a range of minor numbers to work with, asking for a dynamic major * unless directed otherwise at load time. */ 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_minor, 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; } else { printk(KERN_INFO "scull: get major %d success\n", scull_major); }
/* * Allocate the devices. This must be dynamic as the device number can * be specified at load time. */ 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));
/* Initialize each device. */ for (i = 0; i < scull_nr_devs; i++) { scull_devices[i].quantum = scull_quantum; scull_devices[i].qset = scull_qset; mutex_init(&scull_devices[i].mutex); scull_setup_cdev(&scull_devices[i], i); }
return 0; /* succeed */
fail: scull_cleanup_module(); return result; }
module_init(scull_init_module); module_exit(scull_cleanup_module);
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