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

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Date:   Mon, 26 Jul 2021 23:00:51 -0400
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc:     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 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.

     Stefan

>
> /Jarkko