scsi: hisi_sas: Prevent parallel FLR and controller reset

scsi: hisi_sas: Prevent parallel FLR and controller reset

If we issue a controller reset command during executing a FLR a hung task
may be found:

 Call trace:
  __switch_to+0x158/0x1cc
  __schedule+0x2e8/0x85c
  schedule+0x7c/0x110
  schedule_timeout+0x190/0x1cc
  __down+0x7c/0xd4
  down+0x5c/0x7c
  hisi_sas_task_exec+0x510/0x680 [hisi_sas_main]
  hisi_sas_queue_command+0x24/0x30 [hisi_sas_main]
  smp_execute_task_sg+0xf4/0x23c [libsas]
  sas_smp_phy_control+0x110/0x1e0 [libsas]
  transport_sas_phy_reset+0xc8/0x190 [libsas]
  phy_reset_work+0x2c/0x40 [libsas]
  process_one_work+0x1dc/0x48c
  worker_thread+0x15c/0x464
  kthread+0x160/0x170
  ret_from_fork+0x10/0x18

This is a race condition which occurs when the FLR completes first.

Here the host HISI_SAS_RESETTING_BIT flag out gets of sync as
HISI_SAS_RESETTING_BIT is not always cleared with the hisi_hba.sem held, so
now only set/unset HISI_SAS_RESETTING_BIT under hisi_hba.sem .

Link: https://lore.kernel.org/r/1639579061-179473-7-git-send-email-john.garry@huawei.com
Signed-off-by: Qi Liu <liuqi115@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>