linux-kernel - Re: [PATCH] tpm_tis: Add missing start/stop_tpm

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Date:   Tue, 2 Feb 2021 17:33:41 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Łukasz Majczak <lma@...ihalf.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radoslaw Biernacki <rad@...ihalf.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Alex Levin <levinale@...gle.com>,
        James.Bottomley@...senpartnership.com
Subject: Re: [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls

On Sat, Jan 30, 2021 at 03:49:09PM -0800, Guenter Roeck wrote:
> On 1/29/21 2:59 PM, Jarkko Sakkinen wrote:
> > On Tue, Jan 26, 2021 at 04:46:07PM +0100, Łukasz Majczak wrote:
> >> Hi Jarkko, Guenter
> >>
> >> Yes, here are the logs when failure occurs -
> >> https://gist.github.com/semihalf-majczak-lukasz/1575461f585f1e7fb1e9366b8eceaab9
> >> Look for a phrase "TPM returned invalid status"
> >>
> >> Guenter - good suggestion - I will try to keep it as tight as possible.
> >>
> >> Best regards,
> >> Lukasz
> > 
> > Is it possible for you try out with linux-next? Thanks. It's a known
> > issue, which ought to be fixed by now.
> > 
> > The log message is harmless, it'a warning not panic, and does not
> > endanger system stability. WARN()'s always dump stack trace. No oops
> > is happening.
> > 
> 
> There is a note in the kernel documentation which states:
> 
> Note that the WARN()-family should only be used for "expected to
> be unreachable" situations. If you want to warn about "reachable
> but undesirable" situations, please use the pr_warn()-family of
> functions.
> 
> It seems to me that "harmless" doesn't really fit the expected
> use of WARN(). Should it possibly be converted to pr_warn() ?

It should, and I agree that it was a mistake to merge the commit
that added this WARN(). I'm sending a late PR to Linus containing
just the James' fixes. I'll include one line change to that PR,
that does just what you suggested.

It also lacks useful information, i.e. the status.

I just send a fixed with your "suggested-by". Can you review and
ack it ASAP so that I can then go on and send PR to Linus?

/Jarkko