linux-kernel - Re: [PATCH 4/4] gpiolib: cdev: replace locking wrappers for gpio

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Message-ID: <ZYLaayENrvL1Nh6H@rigel>
Date: Wed, 20 Dec 2023 20:13:31 +0800
From: Kent Gibson <warthog618@...il.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>, linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org, andy@...nel.org
Subject: Re: [PATCH 4/4] gpiolib: cdev: replace locking wrappers for
 gpio_device with guards

On Wed, Dec 20, 2023 at 01:05:35PM +0100, Bartosz Golaszewski wrote:
> On Wed, Dec 20, 2023 at 12:56 PM Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > (+PeterZ)
> >
> > On Wed, Dec 20, 2023 at 2:52 AM Kent Gibson <warthog618@...il.com> wrote:
> >
> > > Replace the wrapping functions that inhibit removal of the gpio_device
> > > with equivalent guard macros.
> > >
> > > Signed-off-by: Kent Gibson <warthog618@...il.com>
> > (...)
> > > +DEFINE_CLASS(_read_sem_guard,
> > > +            struct rw_semaphore *,
> > > +            up_read(_T),
> > > +            ({
> > > +               down_read(sem);
> > > +               sem;
> > > +            }),
> > > +            struct rw_semaphore *sem);
> >
> > Isn't this so generic that it should be in <linux/cleanup.h>?
> >
> > Otherwise all the patches look good to me.
> >
>
> We already have this:
>
> DEFINE_GUARD(rwsem_read, struct rw_semaphore *, down_read(_T), up_read(_T))
> DEFINE_GUARD(rwsem_write, struct rw_semaphore *, down_write(_T), up_write(_T))
>
> DEFINE_FREE(up_read, struct rw_semaphore *, if (_T) up_read(_T))
> DEFINE_FREE(up_write, struct rw_semaphore *, if (_T) up_write(_T))
>

Ah - in rwsem.h - I missed that.

> This can surely be used here, right?
>

Don't see why not.

I would still like to move the gpio_device specific macros to gpiolib.h,
as they apply to the struct gpio_device defined there.
The naming probably needs some reworking, so open to suggestions on
that.

Cheers,
Kent.