linux-kernel - RE: Re: [PATCH v19 2/3] scsi: ufs: L2P map management for HPB read

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Date:   Mon, 08 Feb 2021 17:03:33 +0900
From:   Daejun Park <daejun7.park@...sung.com>
To:     Can Guo <cang@...eaurora.org>,
        Daejun Park <daejun7.park@...sung.com>
CC:     Greg KH <gregkh@...uxfoundation.org>,
        "avri.altman@....com" <avri.altman@....com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "huobean@...il.com" <huobean@...il.com>,
        "bvanassche@....org" <bvanassche@....org>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        BoRam Shin <boram.shin@...sung.com>,
        SEUNGUK SHIN <seunguk.shin@...sung.com>
Subject: RE: Re: [PATCH v19 2/3] scsi: ufs: L2P map management for HPB read

> @@ -342,13 +1208,14 @@ void ufshpb_suspend(struct ufs_hba *hba)
> >  	struct scsi_device *sdev;
> > 
> >  	shost_for_each_device(sdev, hba->host) {
> > -		hpb = sdev->hostdata;
> > +		hpb = ufshpb_get_hpb_data(sdev);
> >  		if (!hpb)
> >  			continue;
> > 
> >  		if (ufshpb_get_state(hpb) != HPB_PRESENT)
> >  			continue;
> >  		ufshpb_set_state(hpb, HPB_SUSPEND);
> > +		ufshpb_cancel_jobs(hpb);
> 
> Here may have a dead lock problem - in the case of runtime suspend,
> when ufshpb_suspend() is invoked, all of hba's children scsi devices
> are in RPM_SUSPENDED state. When this line tries to cancel a running
> map work, i.e. when ufshpb_get_map_req() calls below lines, it will
> be stuck at blk_queue_enter().
> 
> req = blk_get_request(hpb->sdev_ufs_lu->request_queue,
> 		      REQ_OP_SCSI_IN, 0);
> 
> Please check block layer power management, and see also commit d55d15a33
> ("scsi: block: Do not accept any requests while suspended").

I am agree with your comment.
How about add BLK_MQ_REQ_NOWAIT flag on blk_get_request() to avoid hang?

Thanks,
Daejun