Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v1 1/2] scsi: ufs: unify scsi_block_requests usage
To:     Stanley Chu <stanley.chu@mediatek.com>, linux-scsi@vger.kernel.org,
        martin.petersen@oracle.com, avri.altman@wdc.com,
        alim.akhtar@samsung.com, pedrom.sousa@synopsys.com,
        jejb@linux.ibm.com, matthias.bgg@gmail.com
Cc:     beanhuo@micron.com, cang@codeaurora.org,
        linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kuohong.wang@mediatek.com, peter.wang@mediatek.com,
        chun-hung.wu@mediatek.com, andy.teng@mediatek.com
References: <1577192466-20762-1-git-send-email-stanley.chu@mediatek.com>
 <1577192466-20762-2-git-send-email-stanley.chu@mediatek.com>
From:   Bart Van Assche <bvanassche@acm.org>
Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata=
 mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr
 LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy
 fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1
 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4
 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB
 AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67
 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M
 Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa
 jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc
 macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD
 CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2
 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5
 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3
 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g
 lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js
 T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc
 ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK
 CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT
 oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y
 //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR
 mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy
 goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e
Message-ID: <e9a8fbc0-5f08-75f5-b23b-2bbaa28a6222@acm.org>
Date:   Tue, 24 Dec 2019 07:46:21 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.3.0
MIME-Version: 1.0
In-Reply-To: <1577192466-20762-2-git-send-email-stanley.chu@mediatek.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2019-12-24 05:01, Stanley Chu wrote:
> Currently UFS driver has ufshcd_scsi_block_requests() with
> reference counter mechanism to avoid possible racing of blocking and
> unblocking requests flow. Unify all users in UFS driver to use the
> same function.
> 
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> ---
>  drivers/scsi/ufs/ufshcd.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index ed02a70..b6b9665 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5177,7 +5177,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
>  	hba = container_of(work, struct ufs_hba, eeh_work);
>  
>  	pm_runtime_get_sync(hba->dev);
> -	scsi_block_requests(hba->host);
> +	ufshcd_scsi_block_requests(hba);
>  	err = ufshcd_get_ee_status(hba, &status);
>  	if (err) {
>  		dev_err(hba->dev, "%s: failed to get exception status %d\n",
> @@ -5191,7 +5191,7 @@ static void ufshcd_exception_event_handler(struct work_struct *work)
>  		ufshcd_bkops_exception_event_handler(hba);
>  
>  out:
> -	scsi_unblock_requests(hba->host);
> +	ufshcd_scsi_unblock_requests(hba);
>  	pm_runtime_put_sync(hba->dev);
>  	return;
>  }

Hi Stanley,

From the SCSI core:

void scsi_block_requests(struct Scsi_Host *shost)
{
	shost->host_self_blocked = 1;
}

In other words, neither scsi_block_requests() nor
ufshcd_scsi_block_requests() wait for ongoing ufshcd_queuecommand()
calls to finish. Is it required to wait for these calls to finish before
exceptions are handled? If not, can the scsi_block_requests() and
scsi_unblock_requests() calls be left out? If it is required to wait for
ongoing ufshcd_queuecommand() calls to finish then I think the
scsi_block_requests() and scsi_unblock_requests() will have to be
changed into something else.

Thanks,

Bart.