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From: Jarkko Sakkinen <jarkko@kernel.org>
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: "Guenter Roeck" <linux@roeck-us.net>,
	"Łukasz Majczak" <lma@semihalf.com>,
	"Peter Huewe" <peterhuewe@gmx.de>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Radoslaw Biernacki" <rad@semihalf.com>,
	"Marcin Wojtas" <mw@semihalf.com>,
	"Alex Levin" <levinale@google.com>
Subject: Re: [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls
Date: Tue, 2 Feb 2021 18:17:34 +0200	[thread overview]
Message-ID: <YBl7HlcgPSX0qRHy@kernel.org> (raw)
In-Reply-To: <bf4564a2f4f761a4c0a00857c7dc346fc43bcd92.camel@HansenPartnership.com>

On Sat, Jan 30, 2021 at 04:41:13PM -0800, James Bottomley wrote:
> On Sat, 2021-01-30 at 15:49 -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 fits the definition.  The warning only triggers if the access is in
> the wrong locality, which should be impossible, so the warning should
> be unreachable.

It's an overkill. Even in perfectly working kernel it's not impossible, as
sometimes hardware gives faulty data. I think that it also lacks the useful
information i.e. the status code.

I would useful WARN() only if the driver state could suffer. In this case
it doesn't. It only results failing transfer but kernel state is still
legit.

/Jarkko
> 

  parent reply	other threads:[~2021-02-02 16:20 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-23  1:42 [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls Lukasz Majczak
2021-01-25 17:12 ` Jarkko Sakkinen
2021-01-25 17:18 ` Guenter Roeck
2021-01-26 15:46   ` Łukasz Majczak
2021-01-26 16:46     ` James Bottomley
2021-01-26 18:55       ` Tj (Elloe Linux)
2021-01-28  5:58       ` Jarkko Sakkinen
2021-01-29 22:59     ` Jarkko Sakkinen
2021-01-29 23:00       ` Jarkko Sakkinen
2021-01-30 23:49       ` Guenter Roeck
2021-01-31  0:41         ` James Bottomley
2021-01-31  3:36           ` Guenter Roeck
2021-01-31  4:18             ` James Bottomley
2021-02-02 16:17           ` Jarkko Sakkinen [this message]
2021-02-02 15:33         ` Jarkko Sakkinen
2021-01-29 22:49   ` Jarkko Sakkinen
2021-01-29 23:32     ` Guenter Roeck
2021-01-28 13:07 ` [PATCH v2] tpm_tis: Add missing tpm_request/relinquish_locality calls Lukasz Majczak
2021-01-28 17:37   ` Guenter Roeck
2021-01-30 20:40   ` Jarkko Sakkinen
2021-01-30 20:47     ` Jarkko Sakkinen
     [not found]     ` <ghwnvtwifq.fsf@gouders.net>
2021-02-02 16:29       ` Jarkko Sakkinen
2021-02-02 15:51   ` [PATCH v3] " Lukasz Majczak
2021-02-02 16:29     ` Guenter Roeck
2021-02-02 22:35       ` Jarkko Sakkinen
2021-02-02 18:47     ` Dirk Gouders
2021-02-03 11:46       ` Dirk Gouders
2021-02-03 13:43         ` Lukasz Majczak
2021-02-03 23:24           ` Jarkko Sakkinen
2021-02-02 19:57     ` [PATCH v4] " Lukasz Majczak
2021-02-02 21:49       ` Jarkko Sakkinen
2021-02-02 21:49     ` [PATCH v3] " Jarkko Sakkinen
2021-02-03  0:05       ` Jarkko Sakkinen
2021-02-03  0:07         ` Jarkko Sakkinen

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