linux-kernel - Re: [PATCH v4 1/4] tpm: add buf_size parameter in the .send callback

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Message-ID: <aB8D5syofPSqjzns@kernel.org>
Date: Sat, 10 May 2025 10:44:38 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: linux-arm-kernel@...ts.infradead.org, Peter Huewe <peterhuewe@....de>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Naveen N Rao <naveen@...nel.org>,
	Jens Wiklander <jens.wiklander@...aro.org>,
	Nicolas Ferre <nicolas.ferre@...rochip.com>,
	linux-integrity@...r.kernel.org,
	Michael Ellerman <mpe@...erman.id.au>,
	Claudiu Beznea <claudiu.beznea@...on.dev>,
	Nicholas Piggin <npiggin@...il.com>,
	Sumit Garg <sumit.garg@...nel.org>
Subject: Re: [PATCH v4 1/4] tpm: add buf_size parameter in the .send callback

On Fri, May 09, 2025 at 10:57:10AM +0200, Stefano Garzarella wrote:
> From: Stefano Garzarella <sgarzare@...hat.com>
> 
> Add a new `buf_size` parameter to the `.send` callback in `tpm_class_ops`.
> This parameter will allow drivers to differentiate between the actual
> command length to send and the total buffer size. Currently `buf_now` is
> not used, but it will be used to implement devices with synchronous send()
> to send the command and receive the response on the same buffer.
> 
> Also rename the previous parameter `len` to `cmd_len` in the declaration
> to make it clear that it contains the length in bytes of the command
> stored in the buffer. The semantics don't change and it can be used as
> before by drivers. This is an optimization since the drivers could get it
> from the header, but let's avoid duplicating code.
> 
> While we are here, resolve a checkpatch warning:
>   WARNING: Unnecessary space before function pointer arguments
>   #66: FILE: include/linux/tpm.h:90:
>   +	int (*send) (struct tpm_chip *chip, u8 *buf, size_t cmd_len,
> 
> Suggested-by: Jarkko Sakkinen <jarkko@...nel.org>
> Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
> ---
> v4:
> - rework the commit description [Jarkko]
> ---
>  include/linux/tpm.h                  | 3 ++-
>  drivers/char/tpm/st33zp24/st33zp24.c | 2 +-
>  drivers/char/tpm/tpm-interface.c     | 2 +-
>  drivers/char/tpm/tpm_atmel.c         | 3 ++-
>  drivers/char/tpm/tpm_crb.c           | 2 +-
>  drivers/char/tpm/tpm_ftpm_tee.c      | 4 +++-
>  drivers/char/tpm/tpm_i2c_atmel.c     | 3 ++-
>  drivers/char/tpm/tpm_i2c_infineon.c  | 3 ++-
>  drivers/char/tpm/tpm_i2c_nuvoton.c   | 3 ++-
>  drivers/char/tpm/tpm_ibmvtpm.c       | 6 ++++--
>  drivers/char/tpm/tpm_infineon.c      | 3 ++-
>  drivers/char/tpm/tpm_nsc.c           | 3 ++-
>  drivers/char/tpm/tpm_svsm.c          | 3 ++-
>  drivers/char/tpm/tpm_tis_core.c      | 3 ++-
>  drivers/char/tpm/tpm_tis_i2c_cr50.c  | 6 ++++--
>  drivers/char/tpm/tpm_vtpm_proxy.c    | 4 +++-
>  drivers/char/tpm/xen-tpmfront.c      | 3 ++-
>  17 files changed, 37 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index 9ac9768cc8f7..7ac390ec89ce 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -87,7 +87,8 @@ struct tpm_class_ops {
>  	const u8 req_complete_val;
>  	bool (*req_canceled)(struct tpm_chip *chip, u8 status);
>  	int (*recv) (struct tpm_chip *chip, u8 *buf, size_t len);
> -	int (*send) (struct tpm_chip *chip, u8 *buf, size_t len);
> +	int (*send)(struct tpm_chip *chip, u8 *buf, size_t cmd_len,
> +		    size_t buf_size);

I'm sorry but now that I look at this, just for the sake of consistency:

	int (*send)(struct tpm_chip *chip, u8 *buf, size_t bufsiz,
		    size_t cmd_len);

I.e. match the order and parameter names from tpm_try_transmit().

BR, Jarkko