[PATCH 6.0 0165/1073] PM: runtime: Do not call __rpm_callback() from rpm_idle()

Greg Kroah-Hartman
2022-12-28T15:14:53Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

[ Upstream commit bc80c2e438dcbfcf748452ec0f7ad5b79ff3ad88 ]

Calling __rpm_callback() from rpm_idle() after adding device links
support to the former is a clear mistake.

Not only it causes rpm_idle() to carry out unnecessary actions, but it
is also against the assumption regarding the stability of PM-runtime
status across __rpm_callback() invocations, because rpm_suspend() and
rpm_resume() may run in parallel with __rpm_callback() when it is called
by rpm_idle() and the device's PM-runtime status can be updated by any
of them.

Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Link: https://lore.kernel.org/linux-pm/36aed941-a73e-d937-2721-4f0decd61ce0@quicinc.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/power/runtime.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 997be3ac20a7..d36fb07190bf 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -484,7 +484,17 @@ static int rpm_idle(struct device *dev, int rpmflags)

dev->power.idle_notification = true;

- retval = __rpm_callback(callback, dev);
+ if (dev->power.irq_safe)
+ spin_unlock(&dev->power.lock);
+ else
+ spin_unlock_irq(&dev->power.lock);
+
+ retval = callback(dev);
+
+ if (dev->power.irq_safe)
+ spin_lock(&dev->power.lock);
+ else
+ spin_lock_irq(&dev->power.lock);

dev->power.idle_notification = false;
wake_up_all(&dev->power.wait_queue);
--
2.35.1