Re: [PATCH 10/10] iio:buffer: Ignore noop requests for iio_update_buffers()

[Jonathan Cameron <jic23@kernel.org>]

On 09/18/13 21:02, Lars-Peter Clausen wrote:
> Since the kernel now disables all buffers when a device is unregistered it might
> happen that a in-kernel consumer tries to disable that buffer again. So ignore
> requests where the buffer already is in the desired state.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> ---
>  drivers/iio/industrialio-buffer.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index 8ceaaaf..2b36cea 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -673,9 +673,21 @@ int iio_update_buffers(struct iio_dev *indio_dev,
>  {
>  	int ret;
>  
> +	if (insert_buffer == remove_buffer)
> +		return 0;
> +
Can this first case occur without a bug in the calling function?

The rest are fine.
>  	mutex_lock(&indio_dev->info_exist_lock);
>  	mutex_lock(&indio_dev->mlock);
>  
> +	if (insert_buffer && iio_buffer_is_active(insert_buffer))
> +		insert_buffer = NULL;
> +
> +	if (remove_buffer && !iio_buffer_is_active(remove_buffer))
> +		remove_buffer = NULL;
> +
> +	if (!insert_buffer && !remove_buffer)
> +		return 0;
> +
>  	if (indio_dev->info == NULL)
>  		return -ENODEV;
>  
>