RDMA/hns: fix possible dead lock when setting RoCE Bonding

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I63IM5



---------------------------------------------------------------------------

When setting RoCE Bonding, a new hr_dev will be registered as
"hns_bond_xx". In the process, the bonding thread will try to acquire
rtnl_lock() while holding roce_bond_mutex. However, it's possible that
another thread running bond_netdev_notify_work() grabs rtnl_lock() before
the bonding thread, and call the bonding notifier function, in which the
thread will try to acquire roce_bond_mutex, finally leading to a dead lock.

As the event informer notifier_call_chain() will not call the next notifier
function until the current one returns, there is no need to use a mutex in
the bonding notifier function. Thus, remove roce_bond_mutex in
hns_roce_bond_event() and the dead lock can be avoided.

Fixes: e62a2027 ("RDMA/hns: support RoCE bonding")
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Reviewed-by: Yangyang Li <liyangyang20@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>