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| author | Marc Zyngier <maz@misterjones.org> | 2010-04-27 13:13:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-04-27 16:26:03 -0700 |
| commit | a2cb9aeb3c9b2475955cec328487484034f414e4 (patch) | |
| tree | 94ca8e8f602150cff3e6f98173c9377db165854c /drivers/gpio/pca953x.c | |
| parent | 3835541dd481091c4dbf5ef83c08aed12e50fd61 (diff) | |
| download | lwn-a2cb9aeb3c9b2475955cec328487484034f414e4.tar.gz lwn-a2cb9aeb3c9b2475955cec328487484034f414e4.zip | |
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>
Diffstat (limited to 'drivers/gpio/pca953x.c')
| -rw-r--r-- | 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 7d521e1d17e1..b827c976dc62 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 = { |