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

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Message-ID: <7a702108-ec9e-b2e2-be89-3590437c0eb5@roeck-us.net>
Date:   Sat, 30 Jan 2021 15:49:09 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Łukasz Majczak <lma@...ihalf.com>
Cc:     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 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() ?

Thanks,
Guenter