From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
commit 887371066039011144b4a94af97d9328df6869a2 upstream.
Because pm_runtime_get_suppliers() bumps up the rpm_active counter
of each device link to a supplier of the given device in addition
to bumping up the supplier's PM-runtime usage counter, a runtime
suspend of the consumer device may case the latter to go down to 0
when pm_runtime_put_suppliers() is running on a remote CPU. If that
happens after pm_runtime_put_suppliers() has released power.lock for
the consumer device, and a runtime resume of that device takes place
immediately after it, before pm_runtime_put() is called for the
supplier, that pm_runtime_put() call may cause the supplier to be
suspended even though the consumer is active.
To prevent that from happening, modify pm_runtime_get_suppliers() to
call pm_runtime_get_sync() for the given device's suppliers without
touching the rpm_active counters of the involved device links
Accordingly, modify pm_runtime_put_suppliers() to call pm_runtime_put()
for the given device's suppliers without looking at the rpm_active
counters of the device links at hand. [This is analogous to what
happened before commit 4c06c4e6cf63 ("driver core: Fix possible
supplier PM-usage counter imbalance").]
Since pm_runtime_get_suppliers() sets supplier_preactivated for each
device link where the supplier's PM-runtime usage counter has been
incremented and pm_runtime_put_suppliers() calls pm_runtime_put() for
the suppliers whose device links have supplier_preactivated set, the
PM-runtime usage counter is balanced for each supplier and this is
independent of the runtime suspend and resume of the consumer device.
However, in case a device link with DL_FLAG_PM_RUNTIME set is dropped
during the consumer device probe, so pm_runtime_get_suppliers() bumps
up the supplier's PM-runtime usage counter, but it cannot be dropped by
pm_runtime_put_suppliers(), make device_link_release_fn() take care of
that.
Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Reported-by: Peter Wang <peter.wang@xxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Peter Wang <peter.wang@xxxxxxxxxxxx>
Cc: 5.1+ <stable@xxxxxxxxxxxxxxx> # 5.1+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/core.c | 10 ++++++++++
drivers/base/power/runtime.c | 14 +-------------
2 files changed, 11 insertions(+), 13 deletions(-)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -486,6 +486,16 @@ static void device_link_release_fn(struc
device_link_synchronize_removal();
pm_runtime_release_supplier(link);
+ /*
+ * If supplier_preactivated is set, the link has been dropped between
+ * the pm_runtime_get_suppliers() and pm_runtime_put_suppliers() calls
+ * in __driver_probe_device(). In that case, drop the supplier's
+ * PM-runtime usage counter to remove the reference taken by
+ * pm_runtime_get_suppliers().
+ */
+ if (link->supplier_preactivated)
+ pm_runtime_put_noidle(link->supplier);
+
pm_request_idle(link->supplier);
put_device(link->consumer);
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1737,7 +1737,6 @@ void pm_runtime_get_suppliers(struct dev
if (link->flags & DL_FLAG_PM_RUNTIME) {
link->supplier_preactivated = true;
pm_runtime_get_sync(link->supplier);
- refcount_inc(&link->rpm_active);
}
device_links_read_unlock(idx);
@@ -1757,19 +1756,8 @@ void pm_runtime_put_suppliers(struct dev
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
device_links_read_lock_held())
if (link->supplier_preactivated) {
- bool put;
-
link->supplier_preactivated = false;
-
- spin_lock_irq(&dev->power.lock);
-
- put = pm_runtime_status_suspended(dev) &&
- refcount_dec_not_one(&link->rpm_active);
-
- spin_unlock_irq(&dev->power.lock);
-
- if (put)
- pm_runtime_put(link->supplier);
+ pm_runtime_put(link->supplier);
}
device_links_read_unlock(idx);
