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

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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>
This commit is contained in:
Jason Gunthorpe 2020-02-27 16:36:51 -04:00
parent 6798241483
commit 32ac9e4399
1 changed files with 13 additions and 0 deletions
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13
drivers/infiniband/core/cma.c
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@ -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;