driver core: Do not call rpm_put_suppliers() in pm_runtime_drop_link()

[ Upstream commit a1fdbfbb1da2063ba98a12eb6f1bdd07451c7145 ]

Calling rpm_put_suppliers() from pm_runtime_drop_link() is excessive
as it affects all suppliers of the consumer device and not just the
one pointed to by the device link being dropped.  Worst case it may
cause the consumer device to stop working unexpectedly.  Moreover, in
principle it is racy with respect to runtime PM of the consumer
device.

To avoid these problems drop runtime PM references on the particular
supplier pointed to by the link in question only and do that after
the link has been dropped from the consumer device's list of links to
suppliers, which is in device_link_free().

Fixes: a0504aecba76 ("PM / runtime: Drop usage count for suppliers at device link removal")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 20ae18f44dcdf6fc8ac9bde94bc1796cb89ff916..7599147d5f83cc40992e52f53c2ed2f67cfababf 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -357,6 +357,9 @@ EXPORT_SYMBOL_GPL(device_link_add);
 
 static void device_link_free(struct device_link *link)
 {
+       while (refcount_dec_not_one(&link->rpm_active))
+               pm_runtime_put(link->supplier);
+
        put_device(link->consumer);
        put_device(link->supplier);
        kfree(link);

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b914932d3ca1a2b3f17216dc48fb910e8add9fb3..ab454c4533ba1a4de63738be4180b8489dffccc3 100644 (file)
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1603,8 +1603,6 @@ void pm_runtime_new_link(struct device *dev)
 
 void pm_runtime_drop_link(struct device *dev)
 {
-       rpm_put_suppliers(dev);
-
        spin_lock_irq(&dev->power.lock);
        WARN_ON(dev->power.links_count == 0);
        dev->power.links_count--;