From: Jarkko Sakkinen <jarkko@kernel.org>
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
linux-integrity@vger.kernel.org,
Guenter Roeck <linux@roeck-us.net>,
stable@vger.kernel.org, Peter Huewe <peterhuewe@gmx.de>,
Jason Gunthorpe <jgg@ziepe.ca>,
Stefan Berger <stefanb@linux.ibm.com>,
Wang Hai <wanghai38@huawei.com>
Subject: Re: [PATCH] tpm: WARN_ONCE() -> pr_warn_once() in tpm_tis_status()
Date: Wed, 3 Feb 2021 00:27:37 +0200 [thread overview]
Message-ID: <YBnR2YLitNJzvNBk@kernel.org> (raw)
In-Reply-To: <1d661a6bdf2d7a9a31b3357ef4170a1309cf2aa4.camel@HansenPartnership.com>
On Tue, Feb 02, 2021 at 09:58:24AM -0800, James Bottomley wrote:
> On Tue, 2021-02-02 at 11:26 -0600, Serge E. Hallyn wrote:
> > On Tue, Feb 02, 2021 at 05:33:17PM +0200, jarkko@kernel.org wrote:
> > > From: Jarkko Sakkinen <jarkko@kernel.org>
> > >
> > > An unexpected status from TPM chip is not irrecovable failure of
> > > the
> > > kernel. It's only undesirable situation. Thus, change the WARN_ONCE
> > > instance inside tpm_tis_status() to pr_warn_once().
> > >
> > > In addition: print the status in the log message because it is
> > > actually
> > > useful information lacking from the existing log message.
> > >
> > > Suggested-by: Guenter Roeck <linux@roeck-us.net>
> > > Cc: stable@vger.kernel.org
> > > Fixes: 6f4f57f0b909 ("tpm: ibmvtpm: fix error return code in
> > > tpm_ibmvtpm_probe()")
> > > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > > ---
> > > drivers/char/tpm/tpm_tis_core.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm_tis_core.c
> > > b/drivers/char/tpm/tpm_tis_core.c
> > > index 431919d5f48a..21f67c6366cb 100644
> > > --- a/drivers/char/tpm/tpm_tis_core.c
> > > +++ b/drivers/char/tpm/tpm_tis_core.c
> > > @@ -202,7 +202,7 @@ static u8 tpm_tis_status(struct tpm_chip *chip)
> > > * acquired. Usually because tpm_try_get_ops() hasn't
> > > * been called before doing a TPM operation.
> > > */
> > > - WARN_ONCE(1, "TPM returned invalid status\n");
> > > + pr_warn_once("TPM returned invalid status: 0x%x\n",
> > > status);
> > > return 0;
> > > }
> >
> > Actually in this case I don't understand why _once, especially based
> > on the comment. Would ratelimited not be better? So we can see if
> > it happens repeatedly? Even better would be if we could see when it
> > next gave a valid status after an invalid one.
>
> The reason was that we're trying to catch and kill paths to the status
> where the locality is incorrect. If you do some operation that finds
> an incorrect path the likelihood is you'll exercise it more than once,
> but all we need to identify it is the call trace from a single access.
> The symptom the user space process sees is a TPM timeout, but we still
> have the in-kernel trace to tell us why.
I don't agree with this reasoning. This warn could spun off also from chip
not following TCG spec. The patch does provide the status code, which is
always useful information.
/Jarkko
next prev parent reply other threads:[~2021-02-02 22:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 15:33 [PATCH] tpm: WARN_ONCE() -> pr_warn_once() in tpm_tis_status() jarkko
2021-02-02 15:43 ` Guenter Roeck
2021-02-02 22:05 ` Jarkko Sakkinen
2021-02-02 16:05 ` Stefan Berger
2021-02-02 22:06 ` Jarkko Sakkinen
2021-02-02 16:46 ` Jason Gunthorpe
2021-02-02 22:25 ` Jarkko Sakkinen
2021-02-02 17:26 ` Serge E. Hallyn
2021-02-02 17:58 ` James Bottomley
2021-02-02 22:27 ` Jarkko Sakkinen [this message]
2021-02-02 22:29 ` Jarkko Sakkinen
2021-02-02 23:00 ` James Bottomley
2021-02-03 0:01 ` Jarkko Sakkinen
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