linux-kernel - Re: [PATCH v4 1/2] tpm: Refactor tpm_transmit pulling out tpm

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Message-Id: <89842442-e92f-6a65-9998-dd5eb186ca4c@linux.vnet.ibm.com>
Date:   Mon, 15 May 2017 12:06:57 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     tpmdd-devel@...ts.sourceforge.net,
        linux-security-module@...r.kernel.org,
        jgunthorpe@...idianresearch.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] tpm: Refactor tpm_transmit pulling out
 tpm_transfer function

On 05/15/2017 12:04 PM, Stefan Berger wrote:
> On 05/15/2017 08:40 AM, Jarkko Sakkinen wrote:
>> On Wed, May 10, 2017 at 07:54:21PM -0400, Stefan Berger wrote:
>>> Refactor tpm_transmit and pull out code sending the command
>>> and receiving the response and put this into tpm_transfer.
>>>
>>> Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
>>> ---
>>>   drivers/char/tpm/tpm-interface.c | 121 
>>> +++++++++++++++++++++++----------------
>>>   1 file changed, 73 insertions(+), 48 deletions(-)
>>>
>>> diff --git a/drivers/char/tpm/tpm-interface.c 
>>> b/drivers/char/tpm/tpm-interface.c
>>> index 158c1db..263b6d1 100644
>>> --- a/drivers/char/tpm/tpm-interface.c
>>> +++ b/drivers/char/tpm/tpm-interface.c
>>> @@ -370,67 +370,29 @@ static bool tpm_validate_command(struct 
>>> tpm_chip *chip,
>>>   }
>>>     /**
>>> - * tmp_transmit - Internal kernel interface to transmit TPM commands.
>>> + * tmp_transfer - Send a TPM command to the TPM and receive response
>>>    *
>>>    * @chip: TPM chip to use
>>>    * @buf: TPM command buffer
>>> + * @count: size of the TPM command
>>>    * @bufsiz: length of the TPM command buffer
>>> - * @flags: tpm transmit flags - bitmap
>>>    *
>>>    * Return:
>>> - *     0 when the operation is successful.
>>> + *     >0 when the operation is successful; returns response length
>>>    *     A negative number for system errors (errno).
>>>    */
>>> -ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
>>> -             u8 *buf, size_t bufsiz, unsigned int flags)
>>> +ssize_t tpm_transfer(struct tpm_chip *chip, u8 *buf, u32 count, 
>>> size_t bufsiz)
>> Add instead a flag TPM_TRANSMIT_RAW (this name is just a suggestion)
>> that skips "prepare" and "commit" parts. That would save us from a
>> new export.
>>
>> Better way to make it less messy would be to add static functions
>> tpm_prepare_command and tpm_commit_command that would be always
>> called and would return immediately if flags contain TPM_TRANSMIT_RAW.
>
> I'll do that then, modifying the code to skip tpm_validate_command as 
> well.
>

But we don't want to recurse (in the 2nd patch) into 
chip->ops->request_locality(). Any suggestions ?

    Stefan