Re: [PATCH 02/10] iio: Keep a reference to the IIO device for open file descriptors

[Jonathan Cameron <jic23@kernel.org>]

On 09/18/13 21:02, Lars-Peter Clausen wrote:
> Make sure that the IIO device is not freed while we still have file descriptors
> for it.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Back ported to the fixes-togreg branch and applied.

Lars.  Either these should have been based on that branch, or
you should have sent a good reason why not.  Whilst these are
rather large and invasive, they are fixing real bugs so
should go into mainline asap as far as I can see.

Jonathan
> ---
>  drivers/iio/industrialio-core.c  |  4 ++++
>  drivers/iio/industrialio-event.c | 19 ++++++++++++++-----
>  2 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 96b35f0..5ea741c 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1012,6 +1012,8 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
>  	if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
>  		return -EBUSY;
>  
> +	iio_device_get(indio_dev);
> +
>  	filp->private_data = indio_dev;
>  
>  	return 0;
> @@ -1025,6 +1027,8 @@ static int iio_chrdev_release(struct inode *inode, struct file *filp)
>  	struct iio_dev *indio_dev = container_of(inode->i_cdev,
>  						struct iio_dev, chrdev);
>  	clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
> +	iio_device_put(indio_dev);
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index 2390e3d..f89843b 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -72,7 +72,8 @@ EXPORT_SYMBOL(iio_push_event);
>  static unsigned int iio_event_poll(struct file *filep,
>  			     struct poll_table_struct *wait)
>  {
> -	struct iio_event_interface *ev_int = filep->private_data;
> +	struct iio_dev *indio_dev = filep->private_data;
> +	struct iio_event_interface *ev_int = indio_dev->event_interface;
>  	unsigned int events = 0;
>  
>  	poll_wait(filep, &ev_int->wait, wait);
> @@ -90,7 +91,8 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
>  				     size_t count,
>  				     loff_t *f_ps)
>  {
> -	struct iio_event_interface *ev_int = filep->private_data;
> +	struct iio_dev *indio_dev = filep->private_data;
> +	struct iio_event_interface *ev_int = indio_dev->event_interface;
>  	unsigned int copied;
>  	int ret;
>  
> @@ -121,7 +123,8 @@ error_unlock:
>  
>  static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
>  {
> -	struct iio_event_interface *ev_int = filep->private_data;
> +	struct iio_dev *indio_dev = filep->private_data;
> +	struct iio_event_interface *ev_int = indio_dev->event_interface;
>  
>  	spin_lock_irq(&ev_int->wait.lock);
>  	__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
> @@ -133,6 +136,8 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
>  	kfifo_reset_out(&ev_int->det_events);
>  	spin_unlock_irq(&ev_int->wait.lock);
>  
> +	iio_device_put(indio_dev);
> +
>  	return 0;
>  }
>  
> @@ -158,12 +163,16 @@ int iio_event_getfd(struct iio_dev *indio_dev)
>  		return -EBUSY;
>  	}
>  	spin_unlock_irq(&ev_int->wait.lock);
> -	fd = anon_inode_getfd("iio:event",
> -				&iio_event_chrdev_fileops, ev_int, O_RDONLY | O_CLOEXEC);
> +
> +	iio_device_get(indio_dev);
> +
> +	fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
> +				indio_dev, O_RDONLY | O_CLOEXEC);
>  	if (fd < 0) {
>  		spin_lock_irq(&ev_int->wait.lock);
>  		__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
>  		spin_unlock_irq(&ev_int->wait.lock);
> +		iio_device_put(indio_dev);
>  	}
>  	return fd;
>  }
>