Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <bf4564a2f4f761a4c0a00857c7dc346fc43bcd92.camel@HansenPartnership.com>
Subject: Re: [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls
From:   James Bottomley <James.Bottomley@HansenPartnership.com>
To:     Guenter Roeck <linux@roeck-us.net>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        =?UTF-8?Q?=C5=81ukasz?= Majczak <lma@semihalf.com>
Cc:     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>
Date:   Sat, 30 Jan 2021 16:41:13 -0800
In-Reply-To: <7a702108-ec9e-b2e2-be89-3590437c0eb5@roeck-us.net>
References: <20210123014247.989368-1-lma@semihalf.com>
         <20210125171846.GA31929@roeck-us.net>
         <CAFJ_xboNDcp-XrxfbrBjqTWjLZUdVWe1OJi4KK==ij+yivFeHA@mail.gmail.com>
         <YBSTOrlgTPpzoblY@kernel.org>
         <7a702108-ec9e-b2e2-be89-3590437c0eb5@roeck-us.net>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.34.4 
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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.

James

> It seems to me that "harmless" doesn't really fit the expected
> use of WARN(). Should it possibly be converted to pr_warn() ?