[PATCH 4.19 33/56] PM: runtime: Fix ordering in pm_runtime_get_suppliers()

From: Greg Kroah-Hartman
Date: Mon Apr 05 2021 - 05:05:14 EST


From: Adrian Hunter <adrian.hunter@xxxxxxxxx>

commit c0c33442f7203704aef345647e14c2fb86071001 upstream.

rpm_active indicates how many times the supplier usage_count has been
incremented. Consequently it must be updated after pm_runtime_get_sync() of
the supplier, not before.

Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: 5.1+ <stable@xxxxxxxxxxxxxxx> # 5.1+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/power/runtime.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1572,8 +1572,8 @@ void pm_runtime_get_suppliers(struct dev
list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
if (link->flags & DL_FLAG_PM_RUNTIME) {
link->supplier_preactivated = true;
- refcount_inc(&link->rpm_active);
pm_runtime_get_sync(link->supplier);
+ refcount_inc(&link->rpm_active);
}

device_links_read_unlock(idx);