drbd: fix drbd_destroy_device reference count updates

drbd_destroy_device means to give up reference counts
on the connection(s) reachable via the peer_device(s).

It must not do that by iterating via device->resource->connections,
resource and connections may have already been disassociated
by drbd_free_resource, and we'd leak connection refs.

Instead, iterate via device->peer_devices->connection.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 92547d16b2c7..56cf11b60cb8 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2160,7 +2160,7 @@ void drbd_destroy_device(struct kref *kref)
 {
         struct drbd_device *device = container_of(kref, struct drbd_device, kref);
         struct drbd_resource *resource = device->resource;
-        struct drbd_connection *connection;
+        struct drbd_peer_device *peer_device, *tmp_peer_device;
 
         del_timer_sync(&device->request_timer);
 
@@ -2191,12 +2191,16 @@ void drbd_destroy_device(struct kref *kref)
         put_disk(device->vdisk);
         blk_cleanup_queue(device->rq_queue);
         kfree(device->rs_plan_s);
-        kfree(first_peer_device(device));
+
+        /* not for_each_connection(connection, resource):
+         * those may have been cleaned up and disassociated already.
+         */
+        for_each_peer_device_safe(peer_device, tmp_peer_device, device) {
+                kref_put(&peer_device->connection->kref, drbd_destroy_connection);
+                kfree(peer_device);
+        }
         memset(device, 0xfd, sizeof(*device));
         kfree(device);
-
-        for_each_connection(connection, resource)
-                kref_put(&connection->kref, drbd_destroy_connection);
         kref_put(&resource->kref, drbd_destroy_resource);
 }