[PATCH 4.14 03/20] PM: runtime: Update device status before letting suppliers suspend

gregkh
2021-03-10T13:28:22Z

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

commit 44cc89f764646b2f1f2ea5d1a08b230131707851 upstream.

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by rpm_put_suppliers() called by it may fail.

Fix this by making __rpm_callback() update the device's status to
RPM_SUSPENDED before calling rpm_put_suppliers() if the current
status of the device is RPM_SUSPENDING and the callback just invoked
by it has returned 0 (success).

While at it, modify the code in __rpm_callback() to always check
the device's PM-runtime status under its PM lock.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Reported-by: Elaine Zhang <zhangqing@rock-chips.com>
Diagnosed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Elaine Zhang <zhangiqng@rock-chips.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: 4.10+ <stable@vger.kernel.org> # 4.10+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/power/runtime.c | 62 +++++++++++++++++++++++++------------------
1 file changed, 37 insertions(+), 25 deletions(-)

--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -306,22 +306,22 @@ static void rpm_put_suppliers(struct dev
static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
- int retval, idx;
bool use_links = dev->power.links_count > 0;
+ bool get = false;
+ int retval, idx;
+ bool put;

if (dev->power.irq_safe) {
spin_unlock(&dev->power.lock);
+ } else if (!use_links) {
+ spin_unlock_irq(&dev->power.lock);
} else {
+ get = dev->power.runtime_status == RPM_RESUMING;
+
spin_unlock_irq(&dev->power.lock);

- /*
- * Resume suppliers if necessary.
- *
- * The device's runtime PM status cannot change until this
- * routine returns, so it is safe to read the status outside of
- * the lock.
- */
- if (use_links && dev->power.runtime_status == RPM_RESUMING) {
+ /* Resume suppliers if necessary. */
+ if (get) {
idx = device_links_read_lock();

retval = rpm_get_suppliers(dev);
@@ -336,24 +336,36 @@ static int __rpm_callback(int (*cb)(stru

if (dev->power.irq_safe) {
spin_lock(&dev->power.lock);
- } else {
- /*
- * If the device is suspending and the callback has returned
- * success, drop the usage counters of the suppliers that have
- * been reference counted on its resume.
- *
- * Do that if resume fails too.
- */
- if (use_links
- && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
- || (dev->power.runtime_status == RPM_RESUMING && retval))) {
- idx = device_links_read_lock();
+ return retval;
+ }

- fail:
- rpm_put_suppliers(dev);
+ spin_lock_irq(&dev->power.lock);

- device_links_read_unlock(idx);
- }
+ if (!use_links)
+ return retval;
+
+ /*
+ * If the device is suspending and the callback has returned success,
+ * drop the usage counters of the suppliers that have been reference
+ * counted on its resume.
+ *
+ * Do that if the resume fails too.
+ */
+ put = dev->power.runtime_status == RPM_SUSPENDING && !retval;
+ if (put)
+ __update_runtime_status(dev, RPM_SUSPENDED);
+ else
+ put = get && retval;
+
+ if (put) {
+ spin_unlock_irq(&dev->power.lock);
+
+ idx = device_links_read_lock();
+
+fail:
+ rpm_put_suppliers(dev);
+
+ device_links_read_unlock(idx);

spin_lock_irq(&dev->power.lock);
}