This lock ordering only happens when bonding is enabled and a certain
bonding related event fires. However, since it can happen this is a global
restriction on lock ordering.
Teach lockdep about the order directly and unconditionally so bugs here
are found quickly.
See https://syzkaller.appspot.com/bug?extid=
55de90ab5f44172b0c90
Link: https://lore.kernel.org/r/20200227203651.GA27185@ziepe.ca
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
{
int ret;
+ /*
+ * There is a rare lock ordering dependency in cma_netdev_callback()
+ * that only happens when bonding is enabled. Teach lockdep that rtnl
+ * must never be nested under lock so it can find these without having
+ * to test with bonding.
+ */
+ if (IS_ENABLED(CONFIG_LOCKDEP)) {
+ rtnl_lock();
+ mutex_lock(&lock);
+ mutex_unlock(&lock);
+ rtnl_unlock();
+ }
+
cma_wq = alloc_ordered_workqueue("rdma_cm", WQ_MEM_RECLAIM);
if (!cma_wq)
return -ENOMEM;