linux-kernel - Re: [PATCH v2 4/5] gpiolib: cdev: reduce locking in gpio_desc_to

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Date:   Fri, 15 Dec 2023 00:05:26 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     Andy Shevchenko <andy@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        brgl@...ev.pl, linus.walleij@...aro.org
Subject: Re: [PATCH v2 4/5] gpiolib: cdev: reduce locking in
 gpio_desc_to_lineinfo()

On Thu, Dec 14, 2023 at 05:50:16PM +0200, Andy Shevchenko wrote:
> On Thu, Dec 14, 2023 at 11:34:44PM +0800, Kent Gibson wrote:
> > On Thu, Dec 14, 2023 at 05:27:29PM +0200, Andy Shevchenko wrote:
> > > On Thu, Dec 14, 2023 at 11:19:01PM +0800, Kent Gibson wrote:
> > > > On Thu, Dec 14, 2023 at 05:10:23PM +0200, Andy Shevchenko wrote:
> > > > > On Thu, Dec 14, 2023 at 05:58:13PM +0800, Kent Gibson wrote:
>
> ...
>
> > > > > > -	spin_lock_irqsave(&gpio_lock, flags);
> > > > >
> > > > > Shouldn't this be covered by patch 1 (I mean conversion to scoped_guard()
> > > > > instead of spinlock)?
> > > >
> > > > Read the cover letter.
> > > > Doing that made the change larger, as flags gets removed then restored.
> > > > I had also thought the flag tests would get indented then unindented, but
> > > > if we use guard() the indentation should remain unchanged.
> > >
> > > I'm fine with that as I pointed out (have you received that mail? I had
> > > problems with my mail server) the dflags is better semantically, so restoration
> > > with _different_ name is fine.
> >
> > I have noted that some of your replies have been delayed, and I can't be sure
> > of what I might not've received. I can't say I've seen one that mentions the
> > dflags name being preferable.
> >
> > I prefer the plain flags name, if there is only one flag variable in the
> > function.
>
> I pointed out that lflags / dflags is kinda idiomatic internally to gpiolib*
> code base. Using flags might feel misleading and otherwise will hint about
> semantics of the variable. That said, I prefer it being named dflags.
>

Application of that idiom in gpiolib-cdev looks to be mixed, but I guess
it can't hurt to lean into it.

Cheers,
Kent.