[PATCH v3] scsi: ufs: correct ufshcd_shutdown flow

[Bart Van Assche]

On 7/24/22 20:47, Peter Wang wrote:
> Because kernel_restart is export, and mediatek may call kernel_restart 
                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Is this code upstream?

> while shutdown is on going.
> EXPORT_SYMBOL_GPL(kernel_restart);
> kernel_restart -> kernel_restart_prepare -> device_shutdown
> 
> So, there may have two thread execute device_shutdown concurrently.
> And the list_lock in device_shutdown function is not protect shutdown 
> callback function,
> caused two callback function(ufshcd_shutdown/ufshcd_wl_shutdown) could 
> run concurrently.
> 
> Here is the error log that two thread in device_shutdown.
> [37684.002227] [T1500641] platform +platform:112b0000.ufshci 
> kpoc_charger: ufshcd-mtk 112b0000.ufshci: [name:core&]shutdown
> [37684.002264] [T1600339] scsi +scsi:0:0:0:49488 charger_thread: 
> ufs_device_wlun 0:0:0:49488: [name:core&]shutdown

Hi Peter,

I had not yet taken a look at the kernel_restart() function. Now that I 
have taken a look, it seems to me that kernel_restart() calls must be 
serialized via the system_transition_mutex. Please make sure that the 
kernel_restart() calls are serialized.

Thanks,

Bart.