Re: [PATCH v2 5/5] iio:buffer: Ignore noop requests for iio_update_buffers()

[Jonathan Cameron <jic23@kernel.org>]

On 10/04/13 12:07, 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>
> ---
> No changes since v1
> ---
>  drivers/iio/industrialio-buffer.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index d6a5455..fd3f3af 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -681,9 +681,23 @@ int iio_update_buffers(struct iio_dev *indio_dev,
>  {
>  	int ret;
>  
> +	if (insert_buffer == remove_buffer)
> +		return 0;
> +
>  	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;
> +
So this condition will occur iff insert_buffer = 0 and remove buffer = 0?

If so, then insert_buffer == remove_buffer and you'll have already returned 0 above??

Entirely possible I'm needing more coffee this morning...
> +	if (!insert_buffer && !remove_buffer) {
> +		ret = 0;
> +		goto out_unlock;
> +	}
> +
>  	if (indio_dev->info == NULL) {
>  		ret = -ENODEV;
>  		goto out_unlock;
>