Message-ID: <3d858407-481b-a55b-4aa9-513e4a4ca44e@acm.org>
Date:   Thu, 9 Mar 2023 09:28:53 -0800
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Subject: Re: [PATCH v1] scsi: ufs: core: print trs for pending requests in MCQ
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To:     Ziqi Chen <quic_ziqichen@quicinc.com>, quic_asutoshd@quicinc.com,
        quic_cang@quicinc.com, quic_nguyenb@quicinc.com, mani@kernel.org,
        stanley.chu@mediatek.com, adrian.hunter@intel.com,
        beanhuo@micron.com, avri.altman@wdc.com, junwoo80.lee@samsung.com,
        martin.petersen@oracle.com
Cc:     linux-scsi@vger.kernel.org, Alim Akhtar <alim.akhtar@samsung.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        open list <linux-kernel@vger.kernel.org>
References: <1678338122-88611-1-git-send-email-quic_ziqichen@quicinc.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <1678338122-88611-1-git-send-email-quic_ziqichen@quicinc.com>
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Precedence: bulk

On 3/8/23 21:01, Ziqi Chen wrote:
> +static void ufshcd_print_trs_all(struct ufs_hba *hba, bool pr_prdt)
> +{
> +	const struct ufshcd_lrb *lrbp;
> +	int tag;
> +
> +	for (tag = 0; tag < hba->nutrs; tag++) {
> +		lrbp = &hba->lrb[tag];
> +
> +		if (lrbp->cmd)
> +			ufshcd_print_tr(hba, tag, pr_prdt);
>   	}
>   }

There is a race in this code: lrbp->cmd may be cleared after it has been 
read and before or while ufshcd_print_tr() is in progress. How about 
preventing that race by blk_mq_tagset_busy_iter() to iterate over 
pending SCSI commands?

Thanks,

Bart.