linux-kernel - Re: [PATCH] iio: buffer: split buffer sysfs creation to take buffer as primary arg

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Date:   Thu, 17 Sep 2020 20:41:08 +0300
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: buffer: split buffer sysfs creation to take buffer
 as primary arg

On Thu, Sep 17, 2020 at 8:18 PM Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Thu, 17 Sep 2020 15:59:51 +0300
> Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:
>
> > Currently the iio_buffer_{alloc,free}_sysfs_and_mask() take 'indio_dev' as
> > primary argument. This change splits the main logic into a private function
> > that takes an IIO buffer as primary argument.
> >
> > That way, the functions can be extended to configure the sysfs for multiple
> > buffers.
> >
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
>
> One comment inline.  Whilst I think it is safe as you have it, I'd
> rather avoid the minor change in logic if we don't need to make it.
>
> Thanks,
>
> Jonathan
>
>
> > ---
> >  drivers/iio/industrialio-buffer.c | 46 ++++++++++++++++++++-----------
> >  1 file changed, 30 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> > index a7d7e5143ed2..a4f6bb96d4f4 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -1264,26 +1264,14 @@ static struct attribute *iio_buffer_attrs[] = {
> >       &dev_attr_data_available.attr,
> >  };
> >
> > -int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
> > +static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
> > +                                          struct iio_dev *indio_dev)
> >  {
> >       struct iio_dev_attr *p;
> >       struct attribute **attr;
> > -     struct iio_buffer *buffer = indio_dev->buffer;
> >       int ret, i, attrn, attrcount;
> >       const struct iio_chan_spec *channels;
> >
> > -     channels = indio_dev->channels;
> > -     if (channels) {
> > -             int ml = indio_dev->masklength;
> > -
> > -             for (i = 0; i < indio_dev->num_channels; i++)
> > -                     ml = max(ml, channels[i].scan_index + 1);
> > -             indio_dev->masklength = ml;
> > -     }
> > -
> > -     if (!buffer)
> > -             return 0;
> > -
> >       attrcount = 0;
> >       if (buffer->attrs) {
> >               while (buffer->attrs[attrcount] != NULL)
> > @@ -1367,19 +1355,45 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
> >       return ret;
> >  }
> >
> > -void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
> > +int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
> >  {
> >       struct iio_buffer *buffer = indio_dev->buffer;
> > +     const struct iio_chan_spec *channels;
> > +     int i;
> > +
> > +     channels = indio_dev->channels;
> > +     if (channels) {
> > +             int ml = indio_dev->masklength;
> > +
> > +             for (i = 0; i < indio_dev->num_channels; i++)
> > +                     ml = max(ml, channels[i].scan_index + 1);
> > +             indio_dev->masklength = ml;
> > +     }
>
> I've not really figured out if it matters, but this is a logic change.
> Previously we didn't compute masklength if there was no buffer provided.
> Now we do.  It's probably better to move the if (!buffer) check above
> this block or at least mention this change in the patch description.
>

Umm, are you referring that this patch is a logic change or you are
suggesting a logic change?
The "if (!buffer)" check was positioned after the masklength
computation even in the old code.

>
> >
> >       if (!buffer)
> > -             return;
> > +             return 0;
> > +
> > +     return __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev);
> > +}
> >
> > +static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
> > +{
> >       bitmap_free(buffer->scan_mask);
> >       kfree(buffer->buffer_group.attrs);
> >       kfree(buffer->scan_el_group.attrs);
> >       iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> >  }
> >
> > +void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
> > +{
> > +     struct iio_buffer *buffer = indio_dev->buffer;
> > +
> > +     if (!buffer)
> > +             return;
> > +
> > +     __iio_buffer_free_sysfs_and_mask(buffer);
> > +}
> > +
> >  /**
> >   * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
> >   * @indio_dev: the iio device
>