[PATCH v20 1/2] scsi: ufs: Enable power management for wlun

[Adrian Hunter]

On 20/04/21 7:15 am, Adrian Hunter wrote:
> On 20/04/21 12:53 am, Asutosh Das (asd) wrote:
>> On 4/19/2021 11:37 AM, Adrian Hunter wrote:
>>> On 16/04/21 10:49 pm, Asutosh Das wrote:
>>>>
>>>> Co-developed-by: Can Guo <cang at codeaurora.org>
>>>> Signed-off-by: Can Guo <cang at codeaurora.org>
>>>> Signed-off-by: Asutosh Das <asutoshd at codeaurora.org>
>>>> ---
>>>
>>> I came across 3 issues while testing.  See comments below.
>>>
>> Hi Adrian
>> Thanks for the comments.
>>> <SNIP>
>>>
>>>> @@ -5794,7 +5839,7 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
>>>>       if (ufshcd_is_clkscaling_supported(hba))
>>>>           ufshcd_clk_scaling_suspend(hba, false);
>>>>       ufshcd_clear_ua_wluns(hba);
>>>
>>> ufshcd_clear_ua_wluns() deadlocks trying to clear UFS_UPIU_RPMB_WLUN
>>> if sdev_rpmb is suspended and sdev_ufs_device is suspending.
>>> e.g. ufshcd_wl_suspend() is waiting on host_sem while ufshcd_err_handler()
>>> is running, at which point sdev_rpmb has already suspended.
>>>
>> Umm, I didn't understand this deadlock.
>> When you say, sdev_rpmb is suspended, does it mean runtime_suspended?
>> sdev_ufs_device is suspending - this can't be runtime_suspending, while ufshcd_err_handling_unprepare is running.
>>
>> If you've a call-stack of this deadlock, please can you share it with me. I'll also try to reproduce this.
> 
> Yes it is system suspend. sdev_rpmb has suspended, sdev_ufs_device is waiting on host_sem.
> ufshcd_err_handler() holds host_sem. ufshcd_clear_ua_wlun(UFS_UPIU_RPMB_WLUN) gets stuck.
> I will get some call-stacks.

Here are the call stacks

[   34.094321] Workqueue: ufs_eh_wq_0 ufshcd_err_handler
[   34.094788] Call Trace:
[   34.095281]  __schedule+0x275/0x6c0
[   34.095743]  schedule+0x41/0xa0
[   34.096240]  blk_queue_enter+0x10d/0x230
[   34.096693]  ? wait_woken+0x70/0x70
[   34.097167]  blk_mq_alloc_request+0x53/0xc0
[   34.097610]  blk_get_request+0x1e/0x60
[   34.098053]  __scsi_execute+0x3c/0x260
[   34.098529]  ufshcd_clear_ua_wlun.cold+0xa6/0x14b
[   34.098977]  ufshcd_clear_ua_wluns.part.0+0x4d/0x92
[   34.099456]  ufshcd_err_handler+0x97a/0x9ff
[   34.099902]  process_one_work+0x1cc/0x360
[   34.100384]  worker_thread+0x45/0x3b0
[   34.100851]  ? process_one_work+0x360/0x360
[   34.101308]  kthread+0xf6/0x130
[   34.101728]  ? kthread_park+0x80/0x80
[   34.102186]  ret_from_fork+0x1f/0x30

[   34.640751] task:kworker/u10:9   state:D stack:14528 pid:  255 ppid:     2 flags:0x00004000
[   34.641253] Workqueue: events_unbound async_run_entry_fn
[   34.641722] Call Trace:
[   34.642217]  __schedule+0x275/0x6c0
[   34.642683]  schedule+0x41/0xa0
[   34.643179]  schedule_timeout+0x18b/0x290
[   34.643645]  ? del_timer_sync+0x30/0x30
[   34.644131]  __down_timeout+0x6b/0xc0
[   34.644568]  ? ufshcd_clkscale_enable_show+0x20/0x20
[   34.645014]  ? async_schedule_node_domain+0x17d/0x190
[   34.645496]  down_timeout+0x42/0x50
[   34.645947]  ufshcd_wl_suspend+0x79/0xa0
[   34.646432]  ? scmd_printk+0x100/0x100
[   34.646917]  scsi_bus_suspend_common+0x56/0xc0
[   34.647405]  ? scsi_bus_freeze+0x10/0x10
[   34.647858]  dpm_run_callback+0x45/0x110
[   34.648347]  __device_suspend+0x117/0x460
[   34.648788]  async_suspend+0x16/0x90
[   34.649251]  async_run_entry_fn+0x26/0x110
[   34.649676]  process_one_work+0x1cc/0x360
[   34.650137]  worker_thread+0x45/0x3b0
[   34.650563]  ? process_one_work+0x360/0x360
[   34.650994]  kthread+0xf6/0x130
[   34.651455]  ? kthread_park+0x80/0x80
[   34.651882]  ret_from_fork+0x1f/0x30



> 
>>
>> I'll address the other comments in the next version.
>>
>>
>> Thank you!
>>
>>>> -    pm_runtime_put(hba->dev);
>>>> +    ufshcd_rpm_put(hba);
>>>>   }
>>>
>>> <SNIP>
>>>
>>>> +void ufshcd_resume_complete(struct device *dev)
>>>> +{
>>
>