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Subject: Re: [PATCH v3 2/3] scsi: ufs: Fix a race condition btw task
 management request send and compl
To:     Can Guo <cang@codeaurora.org>
Cc:     jaegeuk@kernel.org, asutoshd@codeaurora.org,
        nguyenb@codeaurora.org, hongwus@codeaurora.org,
        linux-scsi@vger.kernel.org, kernel-team@android.com,
        Alim Akhtar <alim.akhtar@samsung.com>,
        Avri Altman <avri.altman@wdc.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Bean Huo <beanhuo@micron.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1611807365-35513-1-git-send-email-cang@codeaurora.org>
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 <73362ca9-93be-c38f-a881-4b7cf690fbc1@acm.org>
 <5f77542d66732003f0154a4e8a6ae13b@codeaurora.org>
 <56b26318de92eb88d663bbdc7096edcf@codeaurora.org>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <687cc78a-cb07-bd4f-e1c7-1ff0aeaef6b5@acm.org>
Date:   Sun, 31 Jan 2021 18:27:41 -0800
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On 1/28/21 10:29 PM, Can Guo wrote:
> On second thought, actually the 1st fix alone is enough to eliminate the
> race condition. Because blk_mq_tagset_busy_iter() only iterates over all
> requests which are not in IDLE state, if blk_mq_start_request() is called
> within the protection of host spin lock, ufshcd_compl_tm() shall not run
> into the scenario where req->end_io_data is set but
> REG_UTP_TASK_REQ_DOOR_BELL
> has not been set. What do you think?

That sounds reasonable to me.

Thanks,

Bart.