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Subject: Re: [PATCH V4 1/3] scsi: ufs: Fix error handler clear ua deadlock
To:     Bart Van Assche <bvanassche@acm.org>,
        "Martin K . Petersen" <martin.petersen@oracle.com>
Cc:     "James E . J . Bottomley" <jejb@linux.ibm.com>,
        Bean Huo <huobean@gmail.com>,
        Avri Altman <avri.altman@wdc.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Can Guo <cang@codeaurora.org>,
        Asutosh Das <asutoshd@codeaurora.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Wei Li <liwei213@huawei.com>, linux-scsi@vger.kernel.org
References: <20210916170211.8564-1-adrian.hunter@intel.com>
 <20210916170211.8564-2-adrian.hunter@intel.com>
 <8a3ab601-81c4-8386-b7c8-5bea2ed99002@acm.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <3a8b5325-0bef-b18e-8961-3bfc465096a0@intel.com>
Date:   Fri, 17 Sep 2021 20:39:09 +0300
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On 17/09/21 7:09 pm, Bart Van Assche wrote:
> On 9/16/21 10:02 AM, Adrian Hunter wrote:
>> -static void ufshcd_request_sense_done(struct request *rq, blk_status_t error)
>> +static int ufshcd_request_sense_direct(struct ufs_hba *hba, u8 wlun)
>>   {
> [ ... ]
>> +    /* The command queue cannot be frozen */
>> +    req = blk_get_request(q, REQ_OP_DRV_OUT, 0);
> 
> hba->cmd_queue shares a tag set with the request queues associated with SCSI
> LUNs. Since this blk_get_request() call happens from the context of the error
> handler before SCSI requests are unblocked, it will hang if all tags are
> in use for SCSI requests before the error handler starts.

All the commands sent by ufshcd_probe_hba() take the same approach, so no
difference there.