blob: 40d9f458e1d8684dc1ac69264813a36a1f9daed6 [file] [log] [blame]
From 43b66c8becc15ff3238ce5863b2477fa037f9b16 Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@mellanox.com>
Date: Thu, 27 Feb 2020 16:36:51 -0400
Subject: [PATCH] RDMA/cma: Teach lockdep about the order of rtnl and lock
commit 32ac9e4399b12d3e54d312a0e0e30ed5cd19bd4e upstream.
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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 9b74619d741b..d98ffc5e9682 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -4719,6 +4719,19 @@ static int __init cma_init(void)
{
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;
--
2.7.4