linux-kernel - Re: [PATCH 2/2] tpm: support driver-specific sysfs attrs in tpm_tis

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Date:	Mon, 18 Jul 2016 22:11:41 +0300
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	Andrey Pronin <apronin@...omium.org>
Cc:	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	groeck@...omium.org, smbarber@...omium.org, dianders@...omium.org
Subject: Re: [PATCH 2/2] tpm: support driver-specific sysfs attrs in
 tpm_tis_core

On Thu, Jul 14, 2016 at 06:51:36PM -0700, Andrey Pronin wrote:
> Add attr_group to phy_ops that a driver relying on tpm_tis_core_init
> can set to have its specific attributes registered in sysfs.
> 
> Signed-off-by: Andrey Pronin <apronin@...omium.org>
> ---
>  drivers/char/tpm/tpm-sysfs.c    | 1 -
>  drivers/char/tpm/tpm.h          | 8 +++++++-
>  drivers/char/tpm/tpm_tis_core.c | 3 +++
>  drivers/char/tpm/tpm_tis_core.h | 1 +
>  4 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> index 95ce90d..22c9874 100644
> --- a/drivers/char/tpm/tpm-sysfs.c
> +++ b/drivers/char/tpm/tpm-sysfs.c
> @@ -304,7 +304,6 @@ void tpm_sysfs_add_device(struct tpm_chip *chip)
>  	 * is called before ops is null'd and the sysfs core synchronizes this
>  	 * removal so that no callbacks are running or can run again
>  	 */
> -	WARN_ON(chip->groups_cnt != 0);

You should explain this in a commit message if you want to remove it.

In general, this make user space API vendor specific, which is
unacceptable.

/Jarkko

>  	chip->groups[chip->groups_cnt++] = &tpm_dev_group;
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2)
>  		chip->groups[chip->groups_cnt++] = &tpm2_dev_group;
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 8890df2..8c69649 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -173,7 +173,13 @@ struct tpm_chip {
>  
>  	struct dentry **bios_dir;
>  
> -	const struct attribute_group *groups[3];
> +	/* up to 4 attribute groups:
> +	 * - driver-specific
> +	 * - common TPM1.2 and TPM2.0
> +	 * - TPM1.2/2.0-specific
> +	 * - ppi
> +	 */
> +	const struct attribute_group *groups[5];
>  	unsigned int groups_cnt;
>  #ifdef CONFIG_ACPI
>  	acpi_handle acpi_dev_handle;
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 8110b52..6d5d8f4 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -796,6 +796,9 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
>  		}
>  	}
>  
> +	if (priv->phy_ops->attr_group)
> +		chip->groups[chip->groups_cnt++] = priv->phy_ops->attr_group;
> +
>  	return tpm_chip_register(chip);
>  out_err:
>  	tpm_tis_remove(chip);
> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> index 9191aab..4417ed9 100644
> --- a/drivers/char/tpm/tpm_tis_core.h
> +++ b/drivers/char/tpm/tpm_tis_core.h
> @@ -95,6 +95,7 @@ struct tpm_tis_data {
>  };
>  
>  struct tpm_tis_phy_ops {
> +	const struct attribute_group *attr_group;
>  	int (*read_bytes)(struct tpm_tis_data *data, u32 addr, u16 len,
>  			  u8 *result);
>  	int (*write_bytes)(struct tpm_tis_data *data, u32 addr, u16 len,
> -- 
> 2.6.6
>