Hi Matteo,
originally the `mutex` member of `struct as73211_data` was only intended for
protecting the cached device registers. So can you please update the
documentation of this member?
I can perform some testing für as73211, but I would like to wait until
the "copy data twice" question has been solved. IMHO a solution like Nuno
proposed may be easier to understand.
regards,
Christian
On Monday, 7 October 2024, 10:37:13 CEST, Matteo Martelli wrote:
> While available integration times are being printed to sysfs by iio core
> (iio_read_channel_info_avail), the sampling frequency might be changed.
> This could cause the buffer shared with iio core to be corrupted. To
> prevent it, make a copy of the integration times buffer and free it in
> the read_avail_release_resource callback.
>
> Signed-off-by: Matteo Martelli <matteomartelli3@xxxxxxxxx>
> ---
> drivers/iio/light/as73211.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/light/as73211.c b/drivers/iio/light/as73211.c
> index be0068081ebbbb37fdfb252b67a77b302ff725f6..27bc8cb791039944662a74fc72f09e2c3642cfa6 100644
> --- a/drivers/iio/light/as73211.c
> +++ b/drivers/iio/light/as73211.c
> @@ -493,17 +493,32 @@ static int as73211_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec co
> *type = IIO_VAL_INT;
> return IIO_AVAIL_LIST;
>
> - case IIO_CHAN_INFO_INT_TIME:
> + case IIO_CHAN_INFO_INT_TIME: {
> *length = ARRAY_SIZE(data->int_time_avail);
> - *vals = data->int_time_avail;
> *type = IIO_VAL_INT_PLUS_MICRO;
> - return IIO_AVAIL_LIST;
>
> + guard(mutex)(&data->mutex);
> +
> + *vals = kmemdup_array(data->int_time_avail, *length,
> + sizeof(int), GFP_KERNEL);
> + if (!*vals)
> + return -ENOMEM;
> +
> + return IIO_AVAIL_LIST;
> + }
> default:
> return -EINVAL;
> }
> }
>
> +static void as73211_read_avail_release_res(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + const int *vals, long mask)
> +{
> + if (mask == IIO_CHAN_INFO_INT_TIME)
> + kfree(vals);
> +}
> +
> static int _as73211_write_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan __always_unused,
> int val, int val2, long mask)
> @@ -699,6 +714,7 @@ static irqreturn_t as73211_trigger_handler(int irq __always_unused, void *p)
> static const struct iio_info as73211_info = {
> .read_raw = as73211_read_raw,
> .read_avail = as73211_read_avail,
> + .read_avail_release_resource = as73211_read_avail_release_res,
> .write_raw = as73211_write_raw,
> };
>
>
>
