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.
The offending drivers have been fixed to use _put_sync_suspend(),
But this patch is an RFC to see if it might make sense to allow
using _put_sync() from interrupts-disabled context.
Reported-by: Colin Cross <ccross@xxxxxxxxxx>
Tested-by: Nishanth Menon <nm@xxxxxx>
Signed-off-by: Kevin Hilman <khilman@xxxxxx>
---
drivers/base/power/runtime.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 8dc247c..acb3f83 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -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;
--
1.7.6
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