| From fe65f70e3ddea03d11ba56bed454621f2aad9961 Mon Sep 17 00:00:00 2001 |
| From: Kevin Hilman <khilman@ti.com> |
| Date: Fri, 5 Aug 2011 21:45:20 +0200 |
| Subject: PM / Runtime: Allow _put_sync() from interrupts-disabled context |
| |
| 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> |
| (cherry picked from commit 02b26774afebb2d62695ba3230319d70d8c6cc2d) |
| |
| Signed-off-by: Simon Horman <horms@verge.net.au> |
| --- |
| Documentation/power/runtime_pm.txt | 10 +++++----- |
| drivers/base/power/runtime.c | 10 ++++++++-- |
| 2 files changed, 13 insertions(+), 7 deletions(-) |
| |
| diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt |
| index 14dd3c6..4ce5450 100644 |
| --- a/Documentation/power/runtime_pm.txt |
| +++ b/Documentation/power/runtime_pm.txt |
| @@ -54,11 +54,10 @@ referred to as subsystem-level callbacks in what follows. |
| 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 |
| @@ -483,6 +482,7 @@ pm_runtime_suspend() |
| pm_runtime_autosuspend() |
| pm_runtime_resume() |
| pm_runtime_get_sync() |
| +pm_runtime_put_sync() |
| pm_runtime_put_sync_suspend() |
| |
| 5. Runtime PM Initialization, Device Probing and Removal |
| 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; |
| -- |
| 1.7.10.1.362.g242cab3 |
| |