linux-kernel - Re: [PATCH 08/17] gpiolib: cdev: use blocking notifier call chain instead of atomic

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Message-ID: <CAMpxmJUbd6tFp12q7+iEW5DUEvLdDKhnNMRChatRUUzvshC=iw@mail.gmail.com>
Date:   Thu, 9 Jul 2020 12:06:23 +0200
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Kent Gibson <warthog618@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 08/17] gpiolib: cdev: use blocking notifier call chain
 instead of atomic

On Wed, Jul 8, 2020 at 6:19 AM Kent Gibson <warthog618@...il.com> wrote:
>
> Replace usage of atomic_notifier_call_chain with
> blocking_notifier_call_chain as the notifier function,
> lineinfo_changed_notify, calls gpio_desc_to_lineinfo,
> which calls pinctrl_gpio_can_use_line, which can sleep.
>
> The chain isn't being called from an atomic context so the
> the blocking notifier is a suitable substitute.
>
> Signed-off-by: Kent Gibson <warthog618@...il.com>

In the back of my mind I still think I chose atomic notifiers for a
reason but I can't remember it now. Anyway, we can apply it and see if
anything bad happens and potentially just revert it.

Bart