2015-08-17 08:24:10

by Alexandre Courbot

Subject: [PATCH] gpio/grgpio: fix deadlock in grgpio_irq_unmap()

As reported by Alexey Khoroshilov:

grgpio_irq_unmap() code looks quite suspicious regarding usage of
priv->bgc.lock spinlock.

It locks the spinlock in line 310:

spin_lock_irqsave(&priv->bgc.lock, flags);

and then it can call grgpio_set_imask() in line 317:

grgpio_set_imask(priv, i, 0);

But grgpio_set_imask() unconditionally locks the spinlock by itself.

Fix this by moving the spinlock acquisition outside of
grgpio_set_imask().

Found by Linux Driver Verification project (linuxtesting.org).

Reported-by: Alexey Khoroshilov <[email protected]>
Signed-off-by: Alexandre Courbot <[email protected]>
CC: Alexey Khoroshilov <[email protected]>
CC: Andreas Larsson <[email protected]>
---
drivers/gpio/gpio-grgpio.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index 77053d61466e..801423fe8143 100644
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -104,17 +104,12 @@ static void grgpio_set_imask(struct grgpio_priv *priv, unsigned int offset,
{
struct bgpio_chip *bgc = &priv->bgc;
unsigned long mask = bgc->pin2mask(bgc, offset);
- unsigned long flags;
-
- spin_lock_irqsave(&bgc->lock, flags);

if (val)
priv->imask |= mask;
else
priv->imask &= ~mask;
bgc->write_reg(priv->regs + GRGPIO_IMASK, priv->imask);
-
- spin_unlock_irqrestore(&bgc->lock, flags);
}

static int grgpio_to_irq(struct gpio_chip *gc, unsigned offset)
@@ -180,16 +175,26 @@ static void grgpio_irq_mask(struct irq_data *d)
{
struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
int offset = d->hwirq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->bgc.lock, flags);

grgpio_set_imask(priv, offset, 0);
+
+ spin_unlock_irqrestore(&priv->bgc.lock, flags);
}

static void grgpio_irq_unmask(struct irq_data *d)
{
struct grgpio_priv *priv = irq_data_get_irq_chip_data(d);
int offset = d->hwirq;
+ unsigned long flags;
+
+ spin_lock_irqsave(&priv->bgc.lock, flags);

grgpio_set_imask(priv, offset, 1);
+
+ spin_unlock_irqrestore(&priv->bgc.lock, flags);
}

static struct irq_chip grgpio_irq_chip = {
--
2.5.0

2015-08-17 08:56:20

by Linus Walleij

Subject: Re: [PATCH] gpio/grgpio: fix deadlock in grgpio_irq_unmap()

On Mon, Aug 17, 2015 at 10:23 AM, Alexandre Courbot <[email protected]> wrote:

> As reported by Alexey Khoroshilov:
>
> grgpio_irq_unmap() code looks quite suspicious regarding usage of
> priv->bgc.lock spinlock.
>
> It locks the spinlock in line 310:
>
> spin_lock_irqsave(&priv->bgc.lock, flags);
>
> and then it can call grgpio_set_imask() in line 317:
>
> grgpio_set_imask(priv, i, 0);
>
> But grgpio_set_imask() unconditionally locks the spinlock by itself.
>
> Fix this by moving the spinlock acquisition outside of
> grgpio_set_imask().
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Reported-by: Alexey Khoroshilov <[email protected]>
> Signed-off-by: Alexandre Courbot <[email protected]>
> CC: Alexey Khoroshilov <[email protected]>
> CC: Andreas Larsson <[email protected]>

Patch applied.

Yours,
Linus Walleij