uio: Prevent device destruction while fds are open
Prevent destruction of a uio_device while user space apps hold open file descriptors to that device. Further, access to the 'info' member of the struct uio_device is protected by spinlock. This is to ensure stale pointers to data not under control of the UIO subsystem are not dereferenced. Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz> Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hamish Martin
Greg Kroah-Hartman
parent
81daa406c2
commit
a93e7b3315
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@ -270,7 +270,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
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if (!map_found) {
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map_found = 1;
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idev->map_dir = kobject_create_and_add("maps",
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&idev->dev->kobj);
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&idev->dev.kobj);
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if (!idev->map_dir) {
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ret = -ENOMEM;
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goto err_map;
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@ -299,7 +299,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
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if (!portio_found) {
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portio_found = 1;
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idev->portio_dir = kobject_create_and_add("portio",
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&idev->dev->kobj);
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&idev->dev.kobj);
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if (!idev->portio_dir) {
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ret = -ENOMEM;
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goto err_portio;
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@ -342,7 +342,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
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kobject_put(&map->kobj);
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}
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kobject_put(idev->map_dir);
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dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
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dev_err(&idev->dev, "error creating sysfs files (%d)\n", ret);
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return ret;
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}
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@ -379,7 +379,7 @@ static int uio_get_minor(struct uio_device *idev)
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idev->minor = retval;
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retval = 0;
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} else if (retval == -ENOSPC) {
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dev_err(idev->dev, "too many uio devices\n");
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dev_err(&idev->dev, "too many uio devices\n");
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retval = -EINVAL;
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}
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mutex_unlock(&minor_lock);
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@ -433,6 +433,7 @@ static int uio_open(struct inode *inode, struct file *filep)
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struct uio_device *idev;
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struct uio_listener *listener;
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int ret = 0;
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unsigned long flags;
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mutex_lock(&minor_lock);
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idev = idr_find(&uio_idr, iminor(inode));
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@ -442,9 +443,11 @@ static int uio_open(struct inode *inode, struct file *filep)
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goto out;
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}
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get_device(&idev->dev);
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if (!try_module_get(idev->owner)) {
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ret = -ENODEV;
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goto out;
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goto err_module_get;
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}
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listener = kmalloc(sizeof(*listener), GFP_KERNEL);
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@ -457,11 +460,13 @@ static int uio_open(struct inode *inode, struct file *filep)
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listener->event_count = atomic_read(&idev->event);
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filep->private_data = listener;
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if (idev->info->open) {
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spin_lock_irqsave(&idev->info_lock, flags);
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if (idev->info && idev->info->open)
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ret = idev->info->open(idev->info, inode);
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if (ret)
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goto err_infoopen;
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}
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spin_unlock_irqrestore(&idev->info_lock, flags);
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if (ret)
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goto err_infoopen;
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return 0;
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err_infoopen:
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@ -470,6 +475,9 @@ static int uio_open(struct inode *inode, struct file *filep)
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err_alloc_listener:
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module_put(idev->owner);
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err_module_get:
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put_device(&idev->dev);
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out:
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return ret;
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}
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@ -487,12 +495,16 @@ static int uio_release(struct inode *inode, struct file *filep)
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int ret = 0;
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struct uio_listener *listener = filep->private_data;
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struct uio_device *idev = listener->dev;
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unsigned long flags;
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if (idev->info->release)
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spin_lock_irqsave(&idev->info_lock, flags);
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if (idev->info && idev->info->release)
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ret = idev->info->release(idev->info, inode);
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spin_unlock_irqrestore(&idev->info_lock, flags);
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module_put(idev->owner);
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kfree(listener);
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put_device(&idev->dev);
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return ret;
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}
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@ -500,9 +512,16 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
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{
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struct uio_listener *listener = filep->private_data;
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struct uio_device *idev = listener->dev;
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__poll_t ret = 0;
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unsigned long flags;
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if (!idev->info->irq)
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return -EIO;
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spin_lock_irqsave(&idev->info_lock, flags);
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if (!idev->info || !idev->info->irq)
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ret = -EIO;
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spin_unlock_irqrestore(&idev->info_lock, flags);
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if (ret)
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return ret;
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poll_wait(filep, &idev->wait, wait);
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if (listener->event_count != atomic_read(&idev->event))
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@ -516,11 +535,17 @@ static ssize_t uio_read(struct file *filep, char __user *buf,
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struct uio_listener *listener = filep->private_data;
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struct uio_device *idev = listener->dev;
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DECLARE_WAITQUEUE(wait, current);
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ssize_t retval;
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ssize_t retval = 0;
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s32 event_count;
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unsigned long flags;
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if (!idev->info->irq)
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return -EIO;
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spin_lock_irqsave(&idev->info_lock, flags);
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if (!idev->info || !idev->info->irq)
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retval = -EIO;
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spin_unlock_irqrestore(&idev->info_lock, flags);
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if (retval)
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return retval;
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if (count != sizeof(s32))
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return -EINVAL;
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@ -567,8 +592,10 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
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struct uio_device *idev = listener->dev;
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ssize_t retval;
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s32 irq_on;
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unsigned long flags;
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if (!idev->info->irq) {
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spin_lock_irqsave(&idev->info_lock, flags);
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if (!idev->info || !idev->info->irq) {
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retval = -EIO;
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goto out;
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}
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@ -591,6 +618,7 @@ static ssize_t uio_write(struct file *filep, const char __user *buf,
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retval = idev->info->irqcontrol(idev->info, irq_on);
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out:
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spin_unlock_irqrestore(&idev->info_lock, flags);
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return retval ? retval : sizeof(s32);
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}
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@ -803,6 +831,13 @@ static void release_uio_class(void)
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uio_major_cleanup();
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}
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static void uio_device_release(struct device *dev)
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{
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struct uio_device *idev = dev_get_drvdata(dev);
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kfree(idev);
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}
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/**
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* uio_register_device - register a new userspace IO device
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* @owner: module that creates the new device
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@ -823,13 +858,14 @@ int __uio_register_device(struct module *owner,
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info->uio_dev = NULL;
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idev = devm_kzalloc(parent, sizeof(*idev), GFP_KERNEL);
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idev = kzalloc(sizeof(*idev), GFP_KERNEL);
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if (!idev) {
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return -ENOMEM;
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}
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idev->owner = owner;
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idev->info = info;
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spin_lock_init(&idev->info_lock);
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init_waitqueue_head(&idev->wait);
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atomic_set(&idev->event, 0);
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@ -837,14 +873,19 @@ int __uio_register_device(struct module *owner,
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if (ret)
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return ret;
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idev->dev = device_create(&uio_class, parent,
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MKDEV(uio_major, idev->minor), idev,
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"uio%d", idev->minor);
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if (IS_ERR(idev->dev)) {
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printk(KERN_ERR "UIO: device register failed\n");
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ret = PTR_ERR(idev->dev);
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idev->dev.devt = MKDEV(uio_major, idev->minor);
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idev->dev.class = &uio_class;
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idev->dev.parent = parent;
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idev->dev.release = uio_device_release;
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dev_set_drvdata(&idev->dev, idev);
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ret = dev_set_name(&idev->dev, "uio%d", idev->minor);
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if (ret)
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goto err_device_create;
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ret = device_register(&idev->dev);
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if (ret)
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goto err_device_create;
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}
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ret = uio_dev_add_attributes(idev);
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if (ret)
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@ -872,7 +913,7 @@ int __uio_register_device(struct module *owner,
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err_request_irq:
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uio_dev_del_attributes(idev);
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err_uio_dev_add_attributes:
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device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
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device_unregister(&idev->dev);
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err_device_create:
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uio_free_minor(idev);
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return ret;
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@ -887,6 +928,7 @@ EXPORT_SYMBOL_GPL(__uio_register_device);
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void uio_unregister_device(struct uio_info *info)
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{
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struct uio_device *idev;
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unsigned long flags;
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if (!info || !info->uio_dev)
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return;
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@ -900,7 +942,11 @@ void uio_unregister_device(struct uio_info *info)
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if (info->irq && info->irq != UIO_IRQ_CUSTOM)
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free_irq(info->irq, idev);
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device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
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spin_lock_irqsave(&idev->info_lock, flags);
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idev->info = NULL;
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spin_unlock_irqrestore(&idev->info_lock, flags);
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device_unregister(&idev->dev);
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return;
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}
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@ -14,6 +14,7 @@
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#ifndef _UIO_DRIVER_H_
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#define _UIO_DRIVER_H_
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/interrupt.h>
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@ -68,12 +69,13 @@ struct uio_port {
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struct uio_device {
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struct module *owner;
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struct device *dev;
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struct device dev;
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int minor;
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atomic_t event;
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struct fasync_struct *async_queue;
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wait_queue_head_t wait;
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struct uio_info *info;
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spinlock_t info_lock;
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struct kobject *map_dir;
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struct kobject *portio_dir;
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};
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