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

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Date:   Mon, 15 May 2017 15:40:05 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.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 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.

/Jarkko