linux-kernel - Re: [PATCH 1/2 v2] gpio: gpio-grgpio: fix possible sleep-in-atomic-context bugs in grgpio

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Message-ID: <CACRpkdZEpMDbrHxkaNLiqqaeVKTW3y6k6EpZA8z6nf-9sRF3qQ@mail.gmail.com>
Date:   Tue, 7 Jan 2020 09:59:22 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2 v2] gpio: gpio-grgpio: fix possible
 sleep-in-atomic-context bugs in grgpio_remove()

On Thu, Dec 19, 2019 at 2:15 PM Jia-Ju Bai <baijiaju1990@...il.com> wrote:

> drivers/gpio/gpiolib-sysfs.c, 796:
>         mutex_lock in gpiochip_sysfs_unregister
> drivers/gpio/gpiolib.c, 1455:
>         gpiochip_sysfs_unregister in gpiochip_remove
> drivers/gpio/gpio-grgpio.c, 460:
>         gpiochip_remove in grgpio_remove
> drivers/gpio/gpio-grgpio.c, 449:
>         _raw_spin_lock_irqsave in grgpio_remove
>
> kernel/irq/irqdomain.c, 243:
>         mutex_lock in irq_domain_remove
> drivers/gpio/gpio-grgpio.c, 463:
>         irq_domain_remove in grgpio_remove
> drivers/gpio/gpio-grgpio.c, 449:
>         _raw_spin_lock_irqsave in grgpio_remove
>
> mutex_lock() can sleep at runtime.
>
> To fix these bugs, the lock is dropped in grgpio_remove(), because there
> is no need for locking in remove() callbacks.
>
> These bugs are found by a static analysis tool STCheck written by
> myself.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
> v2:
> * Drop the lock instead of moving the calls to lock functions.
>   Thank Bartosz for good advice.

Looks good to me, patch applied!

Yours,
Linus Walleij