Re: [PATCH] scsi: ufs: fix livelock of ufshcd_clear_ua_wluns

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 12/21, Avri Altman wrote:
> > 
> > 
> > On 12/21, Avri Altman wrote:
> > > > > > When gate_work/ungate_work gets an error during hibern8_enter or
> > > > exit,
> > > > > >  ufshcd_err_handler()
> > > > > >    ufshcd_scsi_block_requests()
> > > > > >    ufshcd_reset_and_restore()
> > > > > >      ufshcd_clear_ua_wluns() -> stuck
> > > > > >    ufshcd_scsi_unblock_requests()
> > > > > >
> > > > > > In order to avoid it, ufshcd_clear_ua_wluns() can be called per
> > recovery
> > > > > > flows
> > > > > > such as suspend/resume, link_recovery, and error_handler.
> > > > > Not sure that suspend/resume are UAC events?
> > > >
> > > > Could you elaborate a bit? The goal is to clear UAC after UFS reset
> > happens.
> > > So why calling it on every suspend and resume?
> > 
> > 1. If UAC was cleared, there's no impact.
> But the command is still sent.

No, ufshcd_clear_ua_wluns() will return by hba->wlun_dev_clr_ua.

> 
> > 2. ufshcd_link_recovery() can reset UFS directly by ufs_mtk_resume().
> > 3. ufshcd_suspend can call ufshcd_host_reset_and_restore() as well.
> Seems excessive IMO.
> Why not selectively send when indeed required, e.g. on reset?

I think hba->wlun_dev_clr_ua is the indicator whether there was a reset or not.