Commit a2cb9aeb authored Apr 27, 2010 by Marc Zyngier Committed by Linus Torvalds Apr 27, 2010

gpio: fix pca953x set_type 'scheduling while atomic' bug



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.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Marc Zyngier <maz@misterjones.org>
Reported-by: Bill Gatliff <bgat@billgatliff.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 3835541d

drivers/gpio/pca953x.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -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 = {

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