Prev: [ANNOUNCE] Git 1.7.1
Next: perf lock: add "info" subcommand for dumping misc information
From: Marc Zyngier on 24 Apr 2010 05:40
Bill Gatliff reported the following bug when using the irq_chip
facility of the pca953x driver on a PPC platform:

BUG: scheduling while atomic: insmod/1530/0x00000002

He traced it back to an i2c transaction in pca953x_irq_set_type(),
which can be called with interrupt disabled (from __setup_irq()). As
the i2c controller can sleep while sending a message, this qualifies
as a bad idea.

This patch moves the i2c transaction to pca953x_irq_bus_sync_unlock(),
where it is actually safe to send an i2c message.

Signed-off-by: Marc Zyngier <maz(a)misterjones.org>
Reported-by: Bill Gatliff <bgat(a)billgatliff.com>
Cc: Eric Miao <eric.y.miao(a)gmail.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
---
drivers/gpio/pca953x.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 7d521e1..d407d84 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -252,6 +252,18 @@ static void pca953x_irq_bus_lock(unsigned int irq)
static void pca953x_irq_bus_sync_unlock(unsigned int irq)
{
struct pca953x_chip *chip = get_irq_chip_data(irq);
+ uint16_t new_irqs;
+ uint16_t level;
+
+ /* Look for any newly setup interrupt */
+ new_irqs = chip->irq_trig_fall | chip->irq_trig_raise;
+ new_irqs &= ~chip->reg_direction;
+
+ while(new_irqs) {
+ level = __ffs(new_irqs);
+ pca953x_gpio_direction_input(&chip->gpio_chip, level);
+ new_irqs &= ~(1 << level);
+ }

mutex_unlock(&chip->irq_lock);
}
@@ -278,7 +290,7 @@ static int pca953x_irq_set_type(unsigned int irq, unsigned int type)
else
chip->irq_trig_raise &= ~mask;

- return pca953x_gpio_direction_input(&chip->gpio_chip, level);
+ return 0;
}

static struct irq_chip pca953x_irq_chip = {
--
1.7.0.6

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [ANNOUNCE] Git 1.7.1
Next: perf lock: add "info" subcommand for dumping misc information