Re: [EXT] Re: [PATCH v2 1/5] scsi; ufs: add device descriptor for Host Performance Booster

[Bart Van Assche]

On 4/23/20 4:01 AM, Bean Huo (beanhuo) wrote:
> Thanks your review, I will take your suggestions in next version development.

Hi Bean,

Please make sure that the issues raised by Christoph are addressed 
before reposting this series.

Additionally, I think the following two call chains are deadlock-prone 
and should be addressed:

ufshcd_queuecommand()
-> ufshcd_comp_scsi_upiu()
  -> ufshpb_prep_fn()
    -> schedule_work(&hpb->ufshpb_req_work)
      -> ufshpb_req_workq_fn()
        -> ufshpb_subregion_activate()
          -> ufshpb_subregion_l2p_load()
            -> ufshpb_l2p_load_req()
              -> blk_execute_rq_nowait()

ufshcd_queuecommand()
-> ufshcd_comp_scsi_upiu()
  -> ufshpb_prep_fn()
    -> schedule_work(&hpb->ufshpb_req_work)
      -> ufshpb_req_workq_fn()
        -> ufshpb_subregion_activate()
        -> ufshpb_region_deactivate()
          -> ufshpb_execute_cmd()
            -> scsi_execute()

I don't know any other block or SCSI driver that calls blk_execute_rq*() 
or scsi_execute() from inside its .queue_rq() callback to queue requests 
onto the same request queue (the device mapper requeues requests onto a 
lower level request queue).

Thanks,

Bart.