linux-kernel - Re: [PATCH] tpm: ibmvtpm: Avoid error message when process gets signal while waiting

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Date:   Thu, 29 Jul 2021 00:50:33 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     Stefan Berger <stefanb@...ux.vnet.ibm.com>, peterhuewe@....de,
        jgg@...pe.ca, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Nayna Jain <nayna@...ux.ibm.com>,
        George Wilson <gcwilson@...ux.ibm.com>,
        Nageswara R Sastry <rnsastry@...ux.ibm.com>
Subject: Re: [PATCH] tpm: ibmvtpm: Avoid error message when process gets
 signal while waiting

On Mon, Jul 26, 2021 at 11:00:51PM -0400, Stefan Berger wrote:
> 
> On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
> > On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
> > > From: Stefan Berger <stefanb@...ux.ibm.com>
> > > 
> > > When rngd is run as root then lots of these types of message will appear
> > > in the kernel log if the TPM has been configure to provide random bytes:
> > > 
> > > [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
> > > 
> > > The issue is caused by the following call that is interrupted while
> > > waiting for the TPM's response.
> > > 
> > > sig = wait_event_interruptible(ibmvtpm->wq,
> > >                                 !ibmvtpm->tpm_processing_cmd);
> > > 
> > > The solution is to use wait_event() instead.
> > Why?
> 
> So it becomes uninterruptible and these error messages go away.

We do not want to make a process uninterruptible. That would prevent
killing it.

/Jarkko