scsi: hisi_sas: Exit suspend state when usage count is greater than 0

When the current status of the host controller is suspended, enabling a
local PHY just after disabling all local PHYs in expander environment, a
hang as follows occurs:

[  486.854655] INFO: task kworker/u256:1:899 blocked for more than 120 seconds.
[  486.862207]       Not tainted 6.1.0-rc4+ #1
[  486.870545] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  486.878893] task:kworker/u256:1  state:D stack:0     pid:899   ppid:2      flags:0x00000008
[  486.887745] Workqueue: 0000:74:02.0_disco_q sas_discover_domain [libsas]
[  486.894704] Call trace:
[  486.897400]  __switch_to+0xf0/0x170
[  486.901146]  __schedule+0x3e4/0x1160
[  486.904970]  schedule+0x64/0x104
[  486.908442]  rpm_resume+0x158/0x6a0
[  486.912163]  __pm_runtime_resume+0x5c/0x84
[  486.916489]  smp_execute_task_sg+0x1f8/0x264 [libsas]
[  486.921773]  sas_discover_expander.part.0+0xbc/0x720 [libsas]
[  486.927750]  sas_discover_root_expander+0x90/0x154 [libsas]
[  486.933552]  sas_discover_domain+0x444/0x6d0 [libsas]
[  486.938826]  process_one_work+0x1e0/0x450
[  486.943057]  worker_thread+0x150/0x44c
[  486.947015]  kthread+0x114/0x120
[  486.950447]  ret_from_fork+0x10/0x20
[  486.954292] INFO: task kworker/u256:2:1780 blocked for more than 120 seconds.
[  486.961637]       Not tainted 6.1.0-rc4+ #1
[  486.966087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  486.974356] task:kworker/u256:2  state:D stack:0     pid:1780  ppid:2      flags:0x00000208
[  486.983141] Workqueue: 0000:74:02.0_event_q sas_port_event_worker [libsas]
[  486.990252] Call trace:
[  486.992930]  __switch_to+0xf0/0x170
[  486.996645]  __schedule+0x3e4/0x1160
[  487.000439]  schedule+0x64/0x104
[  487.003886]  schedule_timeout+0x17c/0x1c0
[  487.008102]  wait_for_completion+0x7c/0x160
[  487.012488]  __flush_workqueue+0x104/0x3e0
[  487.016782]  sas_porte_bytes_dmaed+0x414/0x454 [libsas]
[  487.022203]  sas_port_event_worker+0x38/0x60 [libsas]
[  487.027449]  process_one_work+0x1e0/0x450
[  487.031645]  worker_thread+0x150/0x44c
[  487.035594]  kthread+0x114/0x120
[  487.039017]  ret_from_fork+0x10/0x20
[  487.042828] INFO: task bash:11488 blocked for more than 121 seconds.
[  487.049366]       Not tainted 6.1.0-rc4+ #1
[  487.053746] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  487.061953] task:bash            state:D stack:0     pid:11488 ppid:10977  flags:0x00000204
[  487.070698] Call trace:
[  487.073355]  __switch_to+0xf0/0x170
[  487.077050]  __schedule+0x3e4/0x1160
[  487.080833]  schedule+0x64/0x104
[  487.084270]  schedule_timeout+0x17c/0x1c0
[  487.088474]  wait_for_completion+0x7c/0x160
[  487.092851]  __flush_workqueue+0x104/0x3e0
[  487.097137]  drain_workqueue+0xb8/0x160
[  487.101159]  __sas_drain_work+0x50/0x90 [libsas]
[  487.105963]  sas_suspend_ha+0x64/0xd4 [libsas]
[  487.110590]  suspend_v3_hw+0x198/0x1e8 [hisi_sas_v3_hw]
[  487.115989]  pci_pm_runtime_suspend+0x5c/0x1d0
[  487.120606]  __rpm_callback+0x50/0x150
[  487.124535]  rpm_callback+0x74/0x80
[  487.128204]  rpm_suspend+0x110/0x640
[  487.131955]  rpm_idle+0x1f4/0x2d0
[  487.135447]  __pm_runtime_idle+0x58/0x94
[  487.139538]  queue_phy_enable+0xcc/0xf0 [libsas]
[  487.144330]  store_sas_phy_enable+0x74/0x100
[  487.148770]  dev_attr_store+0x20/0x34
[  487.152606]  sysfs_kf_write+0x4c/0x5c
[  487.156437]  kernfs_fop_write_iter+0x120/0x1b0
[  487.161049]  vfs_write+0x2d0/0x36c
[  487.164625]  ksys_write+0x70/0x100
[  487.168194]  __arm64_sys_write+0x24/0x30
[  487.172280]  invoke_syscall+0x50/0x120
[  487.176186]  el0_svc_common.constprop.0+0x168/0x190
[  487.181214]  do_el0_svc+0x34/0xc0
[  487.184680]  el0_svc+0x2c/0xb4
[  487.187879]  el0t_64_sync_handler+0xb8/0xbc
[  487.192205]  el0t_64_sync+0x19c/0x1a0

We find that when all local PHYs are disabled, all the devices will be
removed, the ->runtime_suspend() callback suspend_v3_hw() directly execute
since the controller usage count drop to 0. On the other side, the first
local PHY is enabled through the sysfs interface, and ensures that function
phy_up_v3_hw() is completed due to suspend_v3_hw()->
interrupt_disable_v3_hw(). In the expander scenario,
sas_discover_root_expander() is executed in event work
DISCE_DISCOVER_DOMAIN, which will increases the controller usage count and
carry out a resume and sends SMPIO, it cannot be completed because the
runtime PM status of the controller is RPM_SUSPENDING. At the same time,
the ->runtime_suspend() callback suspend_v3_hw() also cannot complete the
process because of drain libsas event queue in sas_suspend_ha(), so hung
occurs.

           (thread 1)                   |        (thread 2)
...                                     |
rpm_idle()                              |
 ...                                    |
 __update_runtime_status(RPM_SUSPENDING)|
  ...                                   | ...
  suspend_v3_hw()                       | smp_execute_task_sg()
   ...                                  |  ...
   interrupt_disable_v3_hw()            |  pm_runtime_get_sync()
                                        |   ...
   ...                                  |   rpm_resume() //RPM_SUSPENDING
                                        |
    __sas_drain_work()                  |

To fix this, check if the current runtime PM status of the controller
allows to be suspended continue after interrupt_disable_v3_hw(), return
immediately if not.

Signed-off-by: Yihang Li <liyihang9@huawei.com>
Signed-off-by: Xiang Chen <chenxiang66@hislicon.com>
Link: https://lore.kernel.org/r/1679283265-115066-5-git-send-email-chenxiang66@hisilicon.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>