Commit 32ac9e43 authored Feb 27, 2020 by Jason Gunthorpe

RDMA/cma: Teach lockdep about the order of rtnl and lock

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>

parent 67982414

drivers/infiniband/core/cma.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -4796,6 +4796,19 @@ 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;

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