linux-kernel - Re: [PATCH 3/4] gpiolib: cdev: reduce locking in gpio_desc_to

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Date:   Wed, 13 Dec 2023 17:28:36 +0200
From:   Andy Shevchenko <andy@...nel.org>
To:     Kent Gibson <warthog618@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        brgl@...ev.pl, linus.walleij@...aro.org
Subject: Re: [PATCH 3/4] gpiolib: cdev: reduce locking in
 gpio_desc_to_lineinfo()

On Wed, Dec 13, 2023 at 11:11:34PM +0800, Kent Gibson wrote:
> On Wed, Dec 13, 2023 at 10:07:28PM +0800, Kent Gibson wrote:
> > 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:

...

> > > > -	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?
> 
> Ok, so changing the spin_lock/unlock to
> 
>        scoped_guard(spinlock_irqsave, &gpio_lock) {
>        ...
>        }
> 
> you no longer need the iflags at all, and can rename dflags to flags.

Yes, but I prefer still dflags as it is a distinction from the lock flags
and we use lflags/dflags a lot in GPIO library, so reading the code will
give a hint about the semantics.

> Got it.

-- 
With Best Regards,
Andy Shevchenko