Re: [libgpiod v2.0][PATCH] core: extend config objects

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Thu, Aug 12, 2021 at 3:03 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> On Thu, Aug 12, 2021 at 02:51:02PM +0200, Bartosz Golaszewski wrote:
> > On Thu, Aug 12, 2021 at 12:29 PM Kent Gibson <warthog618@xxxxxxxxx> wrote:
>
> > As you said - it's on the heap, so who cares. But this is also an
> > internal structure and so we can use bit fields. That should reduce
> > the memory footprint significantly as we now don't require more than 3
> > bits for any given enum. That would leave us with the debounce period
> > and offset as full size variables.
>
> Side note (I believe you know about): bit fields are the beasts when you have
> to have a locked access.
>

The library isn't thread-safe. AFAIK a simple mutex around every
operation on a struct containing bitfields will be enough for a user
to guarantee no race conditions in user-space.

Bart