linux-kernel - Re: [PATCH] scsi: ufs: fix livelock of ufshcd_clear_ua

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <X+D5EhJ8QzNoeHQw@google.com>
Date:   Mon, 21 Dec 2020 11:35:46 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Avri Altman <Avri.Altman@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "kernel-team@...roid.com" <kernel-team@...roid.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>
Subject: Re: [PATCH] scsi: ufs: fix livelock of ufshcd_clear_ua_wluns

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.