There is a bug in the current driver in that certain hisi_hba and port
structure elements which we access when servicing the CQ interrupt do
not use thread-safe accesses; these include hisi_sas_port linked-list of
active slots (hisi_sas_port.entry), bitmap of currently allocated IPTT
(in hisi_hba.slot_index_tags), and completion queue read pointer.

As a solution, lock these elements with the hisi_hba.lock.
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NXiang Chen <chenxiang66@hisilicon.com>
Reviewed-by: NZhangfei Gao <zhangfei.gao@linaro.org>
Tested-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>