Skip to contentSkip to conversation

gpio/grgpio: fix deadlock in grgpio_irq_unmap()

PATCH In review Alexandre Courbot 2 participants 2 messages Aug 17, 2015 GPIO

lore
Share & tools
lore

Alexandre Courbot

author
#0 lore raw

PATCH 1/1 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(-)
drivers/gpio/gpio-grgpio.c +10 -5
index 77053d61466e..801423fe8143 100644
@@ -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 = {
Signature · 1 line
2.5.0
#1 lore raw
Quoted 18 lines · Alexandre Courbot

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().

Quoted 6 lines

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