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2c9ede55ec
both callers of device_get_devnode() are only interested in lower 16bits and nobody tries to return anything wider than 16bit anyway. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
374 lines
8.4 KiB
C
374 lines
8.4 KiB
C
/*
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* linux/drivers/char/raw.c
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*
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* Front-end raw character devices. These can be bound to any block
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* devices to provide genuine Unix raw character device semantics.
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*
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* We reserve minor number 0 for a control interface. ioctl()s on this
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* device are used to bind the other minor numbers to block devices.
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/major.h>
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#include <linux/blkdev.h>
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#include <linux/module.h>
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#include <linux/raw.h>
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#include <linux/capability.h>
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#include <linux/uio.h>
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#include <linux/cdev.h>
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#include <linux/device.h>
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#include <linux/mutex.h>
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#include <linux/gfp.h>
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#include <linux/compat.h>
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#include <linux/vmalloc.h>
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#include <asm/uaccess.h>
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struct raw_device_data {
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struct block_device *binding;
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int inuse;
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};
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static struct class *raw_class;
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static struct raw_device_data *raw_devices;
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static DEFINE_MUTEX(raw_mutex);
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static const struct file_operations raw_ctl_fops; /* forward declaration */
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static int max_raw_minors = MAX_RAW_MINORS;
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module_param(max_raw_minors, int, 0);
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MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
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/*
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* Open/close code for raw IO.
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*
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* We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
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* point at the blockdev's address_space and set the file handle to use
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* O_DIRECT.
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*
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* Set the device's soft blocksize to the minimum possible. This gives the
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* finest possible alignment and has no adverse impact on performance.
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*/
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static int raw_open(struct inode *inode, struct file *filp)
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{
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const int minor = iminor(inode);
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struct block_device *bdev;
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int err;
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if (minor == 0) { /* It is the control device */
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filp->f_op = &raw_ctl_fops;
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return 0;
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}
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mutex_lock(&raw_mutex);
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/*
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* All we need to do on open is check that the device is bound.
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*/
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bdev = raw_devices[minor].binding;
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err = -ENODEV;
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if (!bdev)
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goto out;
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igrab(bdev->bd_inode);
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err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
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if (err)
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goto out;
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err = set_blocksize(bdev, bdev_logical_block_size(bdev));
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if (err)
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goto out1;
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filp->f_flags |= O_DIRECT;
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filp->f_mapping = bdev->bd_inode->i_mapping;
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if (++raw_devices[minor].inuse == 1)
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filp->f_path.dentry->d_inode->i_mapping =
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bdev->bd_inode->i_mapping;
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filp->private_data = bdev;
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mutex_unlock(&raw_mutex);
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return 0;
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out1:
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blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
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out:
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mutex_unlock(&raw_mutex);
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return err;
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}
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/*
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* When the final fd which refers to this character-special node is closed, we
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* make its ->mapping point back at its own i_data.
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*/
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static int raw_release(struct inode *inode, struct file *filp)
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{
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const int minor= iminor(inode);
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struct block_device *bdev;
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mutex_lock(&raw_mutex);
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bdev = raw_devices[minor].binding;
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if (--raw_devices[minor].inuse == 0) {
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/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
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inode->i_mapping = &inode->i_data;
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inode->i_mapping->backing_dev_info = &default_backing_dev_info;
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}
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mutex_unlock(&raw_mutex);
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blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
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return 0;
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}
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/*
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* Forward ioctls to the underlying block device.
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*/
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static long
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raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
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{
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struct block_device *bdev = filp->private_data;
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return blkdev_ioctl(bdev, 0, command, arg);
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}
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static int bind_set(int number, u64 major, u64 minor)
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{
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dev_t dev = MKDEV(major, minor);
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struct raw_device_data *rawdev;
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int err = 0;
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if (number <= 0 || number >= max_raw_minors)
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return -EINVAL;
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if (MAJOR(dev) != major || MINOR(dev) != minor)
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return -EINVAL;
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rawdev = &raw_devices[number];
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/*
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* This is like making block devices, so demand the
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* same capability
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*/
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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/*
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* For now, we don't need to check that the underlying
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* block device is present or not: we can do that when
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* the raw device is opened. Just check that the
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* major/minor numbers make sense.
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*/
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if (MAJOR(dev) == 0 && dev != 0)
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return -EINVAL;
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mutex_lock(&raw_mutex);
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if (rawdev->inuse) {
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mutex_unlock(&raw_mutex);
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return -EBUSY;
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}
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if (rawdev->binding) {
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bdput(rawdev->binding);
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module_put(THIS_MODULE);
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}
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if (!dev) {
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/* unbind */
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rawdev->binding = NULL;
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device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
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} else {
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rawdev->binding = bdget(dev);
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if (rawdev->binding == NULL) {
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err = -ENOMEM;
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} else {
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dev_t raw = MKDEV(RAW_MAJOR, number);
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__module_get(THIS_MODULE);
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device_destroy(raw_class, raw);
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device_create(raw_class, NULL, raw, NULL,
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"raw%d", number);
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}
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}
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mutex_unlock(&raw_mutex);
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return err;
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}
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static int bind_get(int number, dev_t *dev)
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{
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struct raw_device_data *rawdev;
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struct block_device *bdev;
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if (number <= 0 || number >= MAX_RAW_MINORS)
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return -EINVAL;
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rawdev = &raw_devices[number];
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mutex_lock(&raw_mutex);
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bdev = rawdev->binding;
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*dev = bdev ? bdev->bd_dev : 0;
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mutex_unlock(&raw_mutex);
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return 0;
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}
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/*
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* Deal with ioctls against the raw-device control interface, to bind
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* and unbind other raw devices.
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*/
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static long raw_ctl_ioctl(struct file *filp, unsigned int command,
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unsigned long arg)
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{
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struct raw_config_request rq;
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dev_t dev;
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int err;
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switch (command) {
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case RAW_SETBIND:
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if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
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return -EFAULT;
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return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
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case RAW_GETBIND:
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if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
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return -EFAULT;
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err = bind_get(rq.raw_minor, &dev);
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if (err)
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return err;
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rq.block_major = MAJOR(dev);
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rq.block_minor = MINOR(dev);
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if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
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return -EFAULT;
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return 0;
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}
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return -EINVAL;
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}
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#ifdef CONFIG_COMPAT
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struct raw32_config_request {
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compat_int_t raw_minor;
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compat_u64 block_major;
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compat_u64 block_minor;
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};
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static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct raw32_config_request __user *user_req = compat_ptr(arg);
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struct raw32_config_request rq;
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dev_t dev;
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int err = 0;
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switch (cmd) {
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case RAW_SETBIND:
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if (copy_from_user(&rq, user_req, sizeof(rq)))
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return -EFAULT;
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return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
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case RAW_GETBIND:
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if (copy_from_user(&rq, user_req, sizeof(rq)))
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return -EFAULT;
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err = bind_get(rq.raw_minor, &dev);
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if (err)
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return err;
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rq.block_major = MAJOR(dev);
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rq.block_minor = MINOR(dev);
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if (copy_to_user(user_req, &rq, sizeof(rq)))
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return -EFAULT;
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return 0;
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}
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return -EINVAL;
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}
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#endif
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static const struct file_operations raw_fops = {
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.read = do_sync_read,
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.aio_read = generic_file_aio_read,
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.write = do_sync_write,
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.aio_write = blkdev_aio_write,
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.fsync = blkdev_fsync,
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.open = raw_open,
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.release = raw_release,
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.unlocked_ioctl = raw_ioctl,
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.llseek = default_llseek,
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.owner = THIS_MODULE,
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};
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static const struct file_operations raw_ctl_fops = {
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.unlocked_ioctl = raw_ctl_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = raw_ctl_compat_ioctl,
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#endif
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.open = raw_open,
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.owner = THIS_MODULE,
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.llseek = noop_llseek,
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};
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static struct cdev raw_cdev;
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static char *raw_devnode(struct device *dev, umode_t *mode)
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{
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return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
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}
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static int __init raw_init(void)
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{
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dev_t dev = MKDEV(RAW_MAJOR, 0);
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int ret;
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if (max_raw_minors < 1 || max_raw_minors > 65536) {
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printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
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" between 1 and 65536), using %d\n", MAX_RAW_MINORS);
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max_raw_minors = MAX_RAW_MINORS;
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}
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raw_devices = vzalloc(sizeof(struct raw_device_data) * max_raw_minors);
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if (!raw_devices) {
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printk(KERN_ERR "Not enough memory for raw device structures\n");
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ret = -ENOMEM;
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goto error;
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}
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ret = register_chrdev_region(dev, max_raw_minors, "raw");
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if (ret)
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goto error;
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cdev_init(&raw_cdev, &raw_fops);
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ret = cdev_add(&raw_cdev, dev, max_raw_minors);
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if (ret) {
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goto error_region;
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}
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raw_class = class_create(THIS_MODULE, "raw");
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if (IS_ERR(raw_class)) {
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printk(KERN_ERR "Error creating raw class.\n");
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cdev_del(&raw_cdev);
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ret = PTR_ERR(raw_class);
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goto error_region;
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}
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raw_class->devnode = raw_devnode;
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device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
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return 0;
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error_region:
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unregister_chrdev_region(dev, max_raw_minors);
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error:
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vfree(raw_devices);
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return ret;
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}
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static void __exit raw_exit(void)
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{
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device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
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class_destroy(raw_class);
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cdev_del(&raw_cdev);
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unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
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}
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module_init(raw_init);
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module_exit(raw_exit);
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MODULE_LICENSE("GPL");
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