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gpio: max732x: Fix possible deadlock 

This patch was derived from next one:
"gpio: fix pca953x set_type 'scheduling while atomic' bug".

After adding entry that consumes max732x GPIO as interrupt line to dts
file, deadlock appears somewhere in max732x probe function.

Deadlock caught by lockdep (from kernel log):
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>>>>>>>>>
[    0.473419] ======================================================
[    0.473419] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
[    0.473449] 3.x.xx-xxxxx-xxxxxxxx-dirty #2 Tainted: G        W
[    0.473449] ------------------------------------------------------
[    0.473449] swapper/0/1 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[    0.473449]  (&lock->wait_lock){+.+...}, at: [<c072e350>] rt_mutex_trylock+0xc/0x74
[    0.473480]
[    0.473480] and this task is already holding:
[    0.473510]  (&chip->lock){......}, at: [<c0314514>] max732x_gpio_set_value+0x2c/0xa4
[    0.473541] which would create a new lock dependency:
[    0.473541]  (&chip->lock){......} -> (&lock->wait_lock){+.+...}

...

[    0.474273]  *** DEADLOCK ***
[    0.474273]
[    0.474273] 5 locks held by swapper/0/1:
[    0.474273]  #0:  (&__lockdep_no_validate__){......}, at: [<c03b2328>] __driver_attach+0x48/0x98
[    0.474304]  #1:  (&__lockdep_no_validate__){......}, at: [<c03b2338>] __driver_attach+0x58/0x98
[    0.474334]  #2:  (&chip->irq_lock){+.+...}, at: [<c0313e3c>] max732x_irq_bus_lock+0x14/0x20
[    0.474365]  #3:  (&irq_desc_lock_class){-.....}, at: [<c00a65a4>] __irq_get_desc_lock+0x48/0x88
[    0.474365]  #4:  (&chip->lock){......}, at: [<c0314514>] max732x_gpio
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>>>>>>>>>

Signed-off-by: Semen Protsenko <semen.protsenko@globallogic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Semen Protsenko 2015-01-13 15:41:44 +02:00 committed by Linus Walleij
parent 479f8a5744
commit 09afa276d5
1 changed files with 11 additions and 1 deletions
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12
drivers/gpio/gpio-max732x.c
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@ -377,8 +377,18 @@ static void max732x_irq_bus_lock(struct irq_data *d)
static void max732x_irq_bus_sync_unlock(struct irq_data *d)
{
struct max732x_chip *chip = irq_data_get_irq_chip_data(d);
uint16_t new_irqs;
uint16_t level;
max732x_irq_update_mask(chip);
new_irqs = chip->irq_trig_fall | chip->irq_trig_raise;
while (new_irqs) {
level = __ffs(new_irqs);
max732x_gpio_direction_input(&chip->gpio_chip, level);
new_irqs &= ~(1 << level);
}
mutex_unlock(&chip->irq_lock);
}
@ -410,7 +420,7 @@ static int max732x_irq_set_type(struct irq_data *d, unsigned int type)
else
chip->irq_trig_raise &= ~mask;
return max732x_gpio_direction_input(&chip->gpio_chip, off);
return 0;
}
static struct irq_chip max732x_irq_chip = {