lkml.org 
[lkml]   [2019]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/2] gpio: gpio-grgpio: fix possible sleep-in-atomic-context bugs in grgpio_remove()
śr., 18 gru 2019 o 14:26 Jia-Ju Bai <baijiaju1990@gmail.com> napisał(a):
>
> The driver may sleep while holding a spinlock.
> The function call path (from bottom to top) in Linux 4.19 is:
>
> 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, gpiochip_remove() and irq_domain_remove() are called
> without holding the spinlock.
>
> These bugs are found by a static analysis tool STCheck written by myself.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> drivers/gpio/gpio-grgpio.c | 5 ++++-
> sound/soc/sti/uniperif_player.c | 3 ++-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
> index 08234e64993a..60a2871c5ba7 100644
> --- a/drivers/gpio/gpio-grgpio.c
> +++ b/drivers/gpio/gpio-grgpio.c
> @@ -448,13 +448,16 @@ static int grgpio_remove(struct platform_device *ofdev)
> }
> }
>
> + spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
> +
> gpiochip_remove(&priv->gc);
>
> if (priv->domain)
> irq_domain_remove(priv->domain);
>
> out:
> - spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);
> + if (ret)
> + spin_unlock_irqrestore(&priv->gc.bgpio_lock, flags);

In general there is no need for locking in remove() callbacks. I guess
you can safely remove the spinlock here all together.

>
> return ret;
> }
> diff --git a/sound/soc/sti/uniperif_player.c b/sound/soc/sti/uniperif_player.c
> index 48ea915b24ba..62244e207679 100644
> --- a/sound/soc/sti/uniperif_player.c
> +++ b/sound/soc/sti/uniperif_player.c
> @@ -601,13 +601,14 @@ static int uni_player_ctl_iec958_put(struct snd_kcontrol *kcontrol,
> mutex_unlock(&player->ctrl_lock);
>
> spin_lock_irqsave(&player->irq_lock, flags);
> + spin_unlock_irqrestore(&player->irq_lock, flags);

Yeah I can tell this was generated automatically - what does this line
is expected to achieve?

Bart

> +
> if (player->substream && player->substream->runtime)
> uni_player_set_channel_status(player,
> player->substream->runtime);
> else
> uni_player_set_channel_status(player, NULL);
>
> - spin_unlock_irqrestore(&player->irq_lock, flags);
> return 0;
> }
>
> --
> 2.17.1
>

\
 
 \ /
  Last update: 2019-12-19 12:11    [W:0.097 / U:8.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site