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PM / Runtime: Allow _put_sync() from interrupts-disabled context

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Currently the use of pm_runtime_put_sync() is not safe from
interrupts-disabled context because rpm_idle() will release the
spinlock and enable interrupts for the idle callbacks.  This enables
interrupts during a time where interrupts were expected to be
disabled, and can have strange side effects on drivers that expected
interrupts to be disabled.

This is not a bug since the documentation clearly states that only
_put_sync_suspend() is safe in IRQ-safe mode.

However, pm_runtime_put_sync() could be made safe when in IRQ-safe
mode by releasing the spinlock but not re-enabling interrupts, which
is what this patch aims to do.

Problem was found when using some buggy drivers that set
pm_runtime_irq_safe() and used _put_sync() in interrupts-disabled
context.

Reported-by: Colin Cross <[email protected]>
Tested-by: Nishanth Menon <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
This commit is contained in:
Kevin Hilman 2011-08-05 21:45:20 +02:00 • committed by Rafael J. Wysocki
commit 02b26774af
2 changed files with 13 additions and 7 deletions
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10
drivers/base/power/runtime.c
View file

@ -226,11 +226,17 @@ static int rpm_idle(struct device *dev, int rpmflags)
callback = NULL;
if (callback) {
spin_unlock_irq(&dev->power.lock);
if (dev->power.irq_safe)
spin_unlock(&dev->power.lock);
else
spin_unlock_irq(&dev->power.lock);
callback(dev);
spin_lock_irq(&dev->power.lock);
if (dev->power.irq_safe)
spin_lock(&dev->power.lock);
else
spin_lock_irq(&dev->power.lock);
}
dev->power.idle_notification = false;