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

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Message-ID: <ZXsa39xneH6Rh7Gd@smile.fi.intel.com>
Date:   Thu, 14 Dec 2023 17:10:23 +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 v2 4/5] gpiolib: cdev: reduce locking in
 gpio_desc_to_lineinfo()

On Thu, Dec 14, 2023 at 05:58:13PM +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 availability of the line from pinctrl if other checks
> pass, so avoiding the check for lines that are otherwise in use.

...

> -	spin_lock_irqsave(&gpio_lock, flags);

Shouldn't this be covered by patch 1 (I mean conversion to scoped_guard()
instead of spinlock)?

-- 
With Best Regards,
Andy Shevchenko