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-rw-r--r--scull/main.c673
1 files changed, 673 insertions, 0 deletions
diff --git a/scull/main.c b/scull/main.c
new file mode 100644
index 0000000..b1d9e3a
--- /dev/null
+++ b/scull/main.c
@@ -0,0 +1,673 @@
+/*
+ * main.c -- the bare scull char module
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files. The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates. No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.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/proc_fs.h>
+#include <linux/fcntl.h> /* O_ACCMODE */
+#include <linux/seq_file.h>
+#include <linux/cdev.h>
+
+#include <asm/system.h> /* cli(), *_flags */
+#include <asm/uaccess.h> /* copy_*_user */
+
+#include "scull.h" /* local definitions */
+
+/*
+ * Our parameters which can be set at load time.
+ */
+
+int scull_major = SCULL_MAJOR;
+int scull_minor = 0;
+int scull_nr_devs = SCULL_NR_DEVS; /* number of bare scull devices */
+int scull_quantum = SCULL_QUANTUM;
+int scull_qset = SCULL_QSET;
+
+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);
+
+MODULE_AUTHOR("Alessandro Rubini, Jonathan Corbet");
+MODULE_LICENSE("Dual BSD/GPL");
+
+struct scull_dev *scull_devices; /* allocated in scull_init_module */
+
+
+/*
+ * Empty out the scull device; must be called with the device
+ * semaphore 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;
+}
+#ifdef SCULL_DEBUG /* use proc only if debugging */
+/*
+ * The proc filesystem: function to read and entry
+ */
+
+int scull_read_procmem(char *buf, char **start, off_t offset,
+ int count, int *eof, void *data)
+{
+ int i, j, len = 0;
+ int limit = count - 80; /* Don't print more than this */
+
+ for (i = 0; i < scull_nr_devs && len <= limit; i++) {
+ struct scull_dev *d = &scull_devices[i];
+ struct scull_qset *qs = d->data;
+ if (down_interruptible(&d->sem))
+ return -ERESTARTSYS;
+ len += sprintf(buf+len,"\nDevice %i: qset %i, q %i, sz %li\n",
+ i, d->qset, d->quantum, d->size);
+ for (; qs && len <= limit; qs = qs->next) { /* scan the list */
+ len += sprintf(buf + len, " item at %p, qset at %p\n",
+ qs, qs->data);
+ if (qs->data && !qs->next) /* dump only the last item */
+ for (j = 0; j < d->qset; j++) {
+ if (qs->data[j])
+ len += sprintf(buf + len,
+ " % 4i: %8p\n",
+ j, qs->data[j]);
+ }
+ }
+ up(&scull_devices[i].sem);
+ }
+ *eof = 1;
+ return len;
+}
+
+
+/*
+ * For now, the seq_file implementation will exist in parallel. The
+ * older read_procmem function should maybe go away, though.
+ */
+
+/*
+ * Here are our sequence iteration methods. Our "position" is
+ * simply the device number.
+ */
+static void *scull_seq_start(struct seq_file *s, loff_t *pos)
+{
+ if (*pos >= scull_nr_devs)
+ return NULL; /* No more to read */
+ return scull_devices + *pos;
+}
+
+static void *scull_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ (*pos)++;
+ if (*pos >= scull_nr_devs)
+ return NULL;
+ return scull_devices + *pos;
+}
+
+static void scull_seq_stop(struct seq_file *s, void *v)
+{
+ /* Actually, there's nothing to do here */
+}
+
+static int scull_seq_show(struct seq_file *s, void *v)
+{
+ struct scull_dev *dev = (struct scull_dev *) v;
+ struct scull_qset *d;
+ int i;
+
+ if (down_interruptible(&dev->sem))
+ return -ERESTARTSYS;
+ seq_printf(s, "\nDevice %i: qset %i, q %i, sz %li\n",
+ (int) (dev - scull_devices), dev->qset,
+ dev->quantum, dev->size);
+ for (d = dev->data; d; d = d->next) { /* scan the list */
+ seq_printf(s, " item at %p, qset at %p\n", d, d->data);
+ if (d->data && !d->next) /* dump only the last item */
+ for (i = 0; i < dev->qset; i++) {
+ if (d->data[i])
+ seq_printf(s, " % 4i: %8p\n",
+ i, d->data[i]);
+ }
+ }
+ up(&dev->sem);
+ return 0;
+}
+
+/*
+ * Tie the sequence operators up.
+ */
+static struct seq_operations scull_seq_ops = {
+ .start = scull_seq_start,
+ .next = scull_seq_next,
+ .stop = scull_seq_stop,
+ .show = scull_seq_show
+};
+
+/*
+ * Now to implement the /proc file we need only make an open
+ * method which sets up the sequence operators.
+ */
+static int scull_proc_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &scull_seq_ops);
+}
+
+/*
+ * Create a set of file operations for our proc file.
+ */
+static struct file_operations scull_proc_ops = {
+ .owner = THIS_MODULE,
+ .open = scull_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release
+};
+
+
+/*
+ * Actually create (and remove) the /proc file(s).
+ */
+
+static void scull_create_proc(void)
+{
+ struct proc_dir_entry *entry;
+ create_proc_read_entry("scullmem", 0 /* default mode */,
+ NULL /* parent dir */, scull_read_procmem,
+ NULL /* client data */);
+ entry = create_proc_entry("scullseq", 0, NULL);
+ if (entry)
+ entry->proc_fops = &scull_proc_ops;
+}
+
+static void scull_remove_proc(void)
+{
+ /* no problem if it was not registered */
+ remove_proc_entry("scullmem", NULL /* parent dir */);
+ remove_proc_entry("scullseq", NULL);
+}
+
+
+#endif /* SCULL_DEBUG */
+
+
+
+
+
+/*
+ * 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 */
+
+ /* now trim to 0 the length of the device if open was write-only */
+ if ( (filp->f_flags & O_ACCMODE) == O_WRONLY) {
+ if (down_interruptible(&dev->sem))
+ return -ERESTARTSYS;
+ scull_trim(dev); /* ignore errors */
+ up(&dev->sem);
+ }
+ return 0; /* success */
+}
+
+int scull_release(struct inode *inode, struct file *filp)
+{
+ return 0;
+}
+/*
+ * Follow the list
+ */
+struct scull_qset *scull_follow(struct scull_dev *dev, int n)
+{
+ struct scull_qset *qs = dev->data;
+
+ /* Allocate first qset explicitly if need be */
+ if (! qs) {
+ qs = dev->data = kmalloc(sizeof(struct scull_qset), GFP_KERNEL);
+ if (qs == NULL)
+ return NULL; /* Never mind */
+ 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; /* Never mind */
+ 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 (down_interruptible(&dev->sem))
+ 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 (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, 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 (down_interruptible(&dev->sem))
+ return -ERESTARTSYS;
+
+ /* 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 */
+ 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 (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:
+ up(&dev->sem);
+ return retval;
+}
+
+/*
+ * The ioctl() implementation
+ */
+
+int scull_ioctl(struct inode *inode, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+
+ int err = 0, tmp;
+ int retval = 0;
+
+ /*
+ * extract the type and number bitfields, and don't decode
+ * wrong cmds: return ENOTTY (inappropriate ioctl) before access_ok()
+ */
+ if (_IOC_TYPE(cmd) != SCULL_IOC_MAGIC) return -ENOTTY;
+ if (_IOC_NR(cmd) > SCULL_IOC_MAXNR) return -ENOTTY;
+
+ /*
+ * the direction is a bitmask, and VERIFY_WRITE catches R/W
+ * transfers. `Type' is user-oriented, while
+ * access_ok is kernel-oriented, so the concept of "read" and
+ * "write" is reversed
+ */
+ 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: /* Set: arg points to the value */
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ retval = __get_user(scull_quantum, (int __user *)arg);
+ break;
+
+ case SCULL_IOCTQUANTUM: /* Tell: arg is the value */
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ scull_quantum = arg;
+ break;
+
+ case SCULL_IOCGQUANTUM: /* Get: arg is pointer to result */
+ retval = __put_user(scull_quantum, (int __user *)arg);
+ break;
+
+ case SCULL_IOCQQUANTUM: /* Query: return it (it's positive) */
+ return scull_quantum;
+
+ case SCULL_IOCXQUANTUM: /* eXchange: use arg as pointer */
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ tmp = scull_quantum;
+ retval = __get_user(scull_quantum, (int __user *)arg);
+ if (retval == 0)
+ retval = __put_user(tmp, (int __user *)arg);
+ break;
+
+ case SCULL_IOCHQUANTUM: /* sHift: like Tell + Query */
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ tmp = scull_quantum;
+ scull_quantum = arg;
+ return tmp;
+
+ case SCULL_IOCSQSET:
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ retval = __get_user(scull_qset, (int __user *)arg);
+ break;
+
+ case SCULL_IOCTQSET:
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ 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:
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ 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:
+ if (! capable (CAP_SYS_ADMIN))
+ return -EPERM;
+ tmp = scull_qset;
+ scull_qset = arg;
+ return tmp;
+
+ /*
+ * The following two change the buffer size for scullpipe.
+ * The scullpipe device uses this same ioctl method, just to
+ * write less code. Actually, it's the same driver, isn't it?
+ */
+
+ case SCULL_P_IOCTSIZE:
+ scull_p_buffer = arg;
+ break;
+
+ case SCULL_P_IOCQSIZE:
+ return scull_p_buffer;
+
+
+ default: /* redundant, as cmd was checked against MAXNR */
+ return -ENOTTY;
+ }
+ return retval;
+
+}
+
+
+
+/*
+ * 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,
+ .ioctl = scull_ioctl,
+ .open = scull_open,
+ .release = scull_release,
+};
+
+/*
+ * Finally, the module stuff
+ */
+
+/*
+ * The cleanup function is used to handle initialization failures as well.
+ * Thefore, it must be careful to work correctly even if some of the items
+ * have not been initialized
+ */
+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);
+ }
+
+#ifdef SCULL_DEBUG /* use proc only if debugging */
+ scull_remove_proc();
+#endif
+
+ /* cleanup_module is never called if registering failed */
+ unregister_chrdev_region(devno, scull_nr_devs);
+
+ /* and call the cleanup functions for friend devices */
+ scull_p_cleanup();
+ scull_access_cleanup();
+
+}
+
+
+/*
+ * 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);
+}
+
+
+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;
+ }
+
+ /*
+ * allocate the devices -- we can't have them static, as the 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; /* Make this more graceful */
+ }
+ 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;
+ init_MUTEX(&scull_devices[i].sem);
+ scull_setup_cdev(&scull_devices[i], i);
+ }
+
+ /* At this point call the init function for any friend device */
+ dev = MKDEV(scull_major, scull_minor + scull_nr_devs);
+ dev += scull_p_init(dev);
+ dev += scull_access_init(dev);
+
+#ifdef SCULL_DEBUG /* only when debugging */
+ scull_create_proc();
+#endif
+
+ return 0; /* succeed */
+
+ fail:
+ scull_cleanup_module();
+ return result;
+}
+
+module_init(scull_init_module);
+module_exit(scull_cleanup_module);
generated by cgit v1.2.1-18-gbd029 (git 2.20.0) at 2025-06-15 12:10:55 +0000