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Subject: Re: [EXT] Re: [PATCH v3 1/1] scsi: ufs: fix LRB pointer incorrect
 initialization issue
To:     "Bean Huo (beanhuo)" <beanhuo@micron.com>,
        "huobean@gmail.com" <huobean@gmail.com>,
        "alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
        "avri.altman@wdc.com" <avri.altman@wdc.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "tomas.winkler@intel.com" <tomas.winkler@intel.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>
Cc:     "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20200309161057.9897-1-beanhuo@micron.com>
 <20200309161057.9897-2-beanhuo@micron.com>
 <ede4addf-73c7-e5f8-5143-91eb0cd3eb9b@acm.org>
 <BN7PR08MB5684F9667DE1CD05D0D01EE6DBFF0@BN7PR08MB5684.namprd08.prod.outlook.com>
From:   Bart Van Assche <bvanassche@acm.org>
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Message-ID: <00b4f8d0-32d3-58c7-6361-6177ed8aaaed@acm.org>
Date:   Tue, 10 Mar 2020 20:49:48 -0700
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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.