Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200731123835.8003-1-a.fatoum@pengutronix.de>
In-Reply-To: <20200731123835.8003-1-a.fatoum@pengutronix.de>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Tue, 4 Aug 2020 01:23:11 +0200
Message-ID: <CACRpkdbhpFae+Phf6Vxih7f2eMWAkYArmi8Bwp_yMEsVpG5xgQ@mail.gmail.com>
Subject: Re: [PATCH] gpio: don't use same lockdep class for all
 devm_gpiochip_add_data users
To:     Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc:     Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Thierry Reding <treding@nvidia.com>,
        Sascha Hauer <kernel@pengutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Jul 31, 2020 at 2:39 PM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:

> Commit 959bc7b22bd2 ("gpio: Automatically add lockdep keys") documents
> in its commits message its intention to "create a unique class key for
> each driver".
>
> It does so by having gpiochip_add_data add in-place the definition of
> two static lockdep classes for LOCKDEP use. That way, every caller of
> the macro adds their gpiochip with unique lockdep classes.
>
> There are many indirect callers of gpiochip_add_data, however, via
> use of devm_gpiochip_add_data. devm_gpiochip_add_data has external
> linkage and all its users will share the same lockdep classes, which
> probably is not intended.
>
> Fix this by replicating the gpio_chip_add_data statics-in-macro for
> the devm_ version as well.
>
> Fixes: 959bc7b22bd2 ("gpio: Automatically add lockdep keys")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
> This doesn't fix any particular problem I ran into, but the code
> looked buggy, at least to my lockdep-user-not-developer eyes.

Thanks patch applied, I think we had this fixed before
but managed to loose it in some API rewrite. Thanks for
fixing it up!

Yours,
Linus Walleij