Re: [PATCH 3/4] gpiolib: cdev: reduce locking in gpio_desc_to_lineinfo()

[Kent Gibson <warthog618@xxxxxxxxx>]

On Wed, Dec 13, 2023 at 03:56:27PM +0200, Andy Shevchenko wrote:
> On Tue, Dec 12, 2023 at 01:42:52PM +0800, Kent Gibson wrote:
> > Reduce the time holding the gpio_lock by snapshotting the desc flags,
> > rather than testing them individually while holding the lock.
> >
> > Accept that the calculation of the used field is inherently racy, and
> > only check the availabilty of the line from pinctrl if other checks
> > pass, so avoiding the check for lines that are otherwise in use.
>
> ...
>
> > -	bool ok_for_pinctrl;
> > -	unsigned long flags;
> > +	unsigned long iflags, dflags;
>
> With a preliminary conversion to cleanup.h this whole change becomes cleaner,
> no?
>

You mean the scoped guards?  Dunno - haven't used them.
Care to provide more detail?

Cheers,
Kent.