Re: [EXT] Re: [PATCH v3 1/1] scsi: ufs: fix LRB pointer incorrect initialization issue

[Bart Van Assche <bvanassche@acm.org>]

On 2020-03-10 00:53, Bean Huo (beanhuo) wrote:
> Hi, Bart 
> 
>> Subject: [EXT] Re: [PATCH v3 1/1] scsi: ufs: fix LRB pointer incorrect initialization
>> issue
>>
>> On 2020-03-09 09:10, huobean@gmail.com wrote:
>>> @@ -4834,6 +4829,7 @@ static void __ufshcd_transfer_req_compl(struct
>> ufs_hba *hba,
>>>  			continue;
>>>  		cmd = blk_mq_rq_to_pdu(req);
>>>  		lrbp = scsi_cmd_priv(cmd);
>>> +		ufshcd_init_lrb(hba, lrbp, index);
>>>  		if (ufshcd_is_scsi(req)) {
>>>  			ufshcd_add_command_trace(hba, req, "complete");
>>>  			result = ufshcd_transfer_rsp_status(hba, lrbp);
>>
>> This ufshcd_init_lrb() call looks incorrect to me. I think that
>> ufshcd_init_lrb() should only be called before a request is submitted to the UFS
>> controller and also that ufshcd_init_lrb() should not be called from the
>> completion path.
> 
> __ufshcd_transfer_req_compl()
> 	ufshcd_transfer_rsp_status()  will access lrbp->ucd_rsp_ptr.
> Without calling ufshcd_init_lrb() here, there will be an error.

Hi Bean,

I think that ufshcd_init_lrb() should only be called from the code that
prepares a command before it is submitted and not from the command
completion path. Because v5.6-rc5 has already been released, there is
not that much time left until the merge window opens. I think it is less
risky to revert commit 34656dda81ac ("scsi: ufs: Let the SCSI core
allocate per-command UFS data") than to proceed with the above patch. Do
you want to submit a revert or do you perhaps want me to do that?

Thanks,

Bart.