Re: [PATCH RFT] iio: Fix core buffer demux failure to account for unwanted channels at tail

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Mon, 4 Aug 2025 14:52:23 +0200
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Mon, Aug 4, 2025 at 12:48 PM Jonathan Cameron
> <Jonathan.Cameron@huawei.com> wrote:
> > On Sun, 3 Aug 2025 21:46:50 +0200
> > Andy Shevchenko <andy.shevchenko@gmail.com> wrote:  
> > > On Sat, Aug 2, 2025 at 7:15 PM Jonathan Cameron <jic23@kernel.org> wrote:  
> 
> ...
> 
> > > > +       /* Walk remaining bits of active_scan_mask */
> > > > +       in_ind = find_next_bit(indio_dev->active_scan_mask, masklength,
> > > > +                              in_ind + 1);
> > > > +       while (in_ind != masklength) {  
> > >
> > > for_each_set_bit_from() ?  
> >
> > Would work but then takes the style away from the code above that this
> > effectively duplicates.  I'd need to have a closer look to see if we
> > can potentially convert that as well.  I don't want two very different
> > looking bits of code effectively doing the same thing under subtly
> > different constraints.  
> 
> I see. But can we have this as a fix followed by the conversion patch
> in one series, so we won't forget about that?

Maybe.  This is a nasty bug so I'm not sure I want to delay the fix
whilst I work out how to cleanup the section above.

I'll see if I can find time to work on this. The time is mostly on
building test cases rather than the code.
> 
> > > > +               ret = iio_storage_bytes_for_si(indio_dev, in_ind);
> > > > +               if (ret < 0)
> > > > +                       goto error_clear_mux_table;
> > > > +
> > > > +               length = ret;
> > > > +               /* Make sure we are aligned */
> > > > +               in_loc = roundup(in_loc, length) + length;
> > > > +               in_ind = find_next_bit(indio_dev->active_scan_mask,
> > > > +                                      masklength, in_ind + 1);
> > > > +       }  
> 
>