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 <ccross@google.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
By default, the callbacks are always invoked in process context with interrupts
enabled. However, subsystems can use the pm_runtime_irq_safe() helper function
to tell the PM core that a device's ->runtime_suspend() and ->runtime_resume()
By default, the callbacks are always invoked in process context with interrupts
enabled. However, subsystems can use the pm_runtime_irq_safe() helper function
to tell the PM core that a device's ->runtime_suspend() and ->runtime_resume()
-callbacks should be invoked in atomic context with interrupts disabled
-(->runtime_idle() is still invoked the default way). This implies that these
-callback routines must not block or sleep, but it also means that the
-synchronous helper functions listed at the end of Section 4 can be used within
-an interrupt handler or in an atomic context.
+callbacks should be invoked in atomic context with interrupts disabled.
+This implies that these callback routines must not block or sleep, but it also
+means that the synchronous helper functions listed at the end of Section 4 can
+be used within an interrupt handler or in an atomic context.
The subsystem-level suspend callback is _entirely_ _responsible_ for handling
the suspend of the device as appropriate, which may, but need not include
The subsystem-level suspend callback is _entirely_ _responsible_ for handling
the suspend of the device as appropriate, which may, but need not include
pm_runtime_autosuspend()
pm_runtime_resume()
pm_runtime_get_sync()
pm_runtime_autosuspend()
pm_runtime_resume()
pm_runtime_get_sync()
pm_runtime_put_sync_suspend()
5. Runtime PM Initialization, Device Probing and Removal
pm_runtime_put_sync_suspend()
5. Runtime PM Initialization, Device Probing and Removal
callback = NULL;
if (callback) {
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);
- 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;
}
dev->power.idle_notification = false;