linux-kernel - Re: [PATCH v11 08/16] tpm: clean up tpm_try

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Message-Id: <5203f941-9516-0e91-7dc7-d5b9892c82ec@linux.ibm.com>
Date:   Thu, 7 Feb 2019 18:36:59 -0500
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Peter Huewe <PeterHuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH v11 08/16] tpm: clean up tpm_try_transmit() error handling
 flow

On 2/5/19 5:47 PM, Jarkko Sakkinen wrote:
> Move locking, locality handling and power management to tpm_transmit()
> in order to simplify the flow.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
> Tested-by: Stefan Berger <stefanb@...ux.ibm.com>
> Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>
> Reviewed-by: James Bottomley <James.Bottomley@...senPartnership.com>
> ---
>   drivers/char/tpm/tpm-interface.c | 94 +++++++++++++++-----------------
>   drivers/char/tpm/tpm.h           |  1 +
>   drivers/char/tpm/tpm2-space.c    |  2 +-
>   3 files changed, 45 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index c28ffef92f1a..f5f5224f68b0 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -167,7 +167,6 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   	ssize_t len = 0;
>   	u32 count, ordinal;
>   	unsigned long stop;
> -	bool need_locality;
>
>   	rc = tpm_validate_command(chip, space, buf, bufsiz);
>   	if (rc == -EINVAL)
> @@ -197,37 +196,16 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   		return -E2BIG;
>   	}
>
> -	if (!(flags & TPM_TRANSMIT_UNLOCKED) && !(flags & TPM_TRANSMIT_NESTED))
> -		mutex_lock(&chip->tpm_mutex);
> -
> -	if (chip->ops->clk_enable != NULL)
> -		chip->ops->clk_enable(chip, true);
> -
> -	/* Store the decision as chip->locality will be changed. */
> -	need_locality = chip->locality == -1;
> -
> -	if (need_locality) {
> -		rc = tpm_request_locality(chip, flags);
> -		if (rc < 0) {
> -			need_locality = false;
> -			goto out_locality;
> -		}
> -	}
> -
> -	rc = tpm_cmd_ready(chip, flags);
> -	if (rc)
> -		goto out_locality;
> -
>   	rc = tpm2_prepare_space(chip, space, ordinal, buf);
>   	if (rc)
> -		goto out;
> +		return rc;
>
>   	rc = chip->ops->send(chip, buf, count);
>   	if (rc < 0) {
>   		if (rc != -EPIPE)
>   			dev_err(&chip->dev,
>   				"%s: tpm_send: error %d\n", __func__, rc);
> -		goto out;
> +		goto out_rc;
>   	}
>
>   	if (chip->flags & TPM_CHIP_FLAG_IRQ)
> @@ -243,7 +221,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   		if (chip->ops->req_canceled(chip, status)) {
>   			dev_err(&chip->dev, "Operation Canceled\n");
>   			rc = -ECANCELED;
> -			goto out;
> +			goto out_rc;
>   		}
>
>   		tpm_msleep(TPM_TIMEOUT_POLL);
> @@ -253,40 +231,20 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   	chip->ops->cancel(chip);
>   	dev_err(&chip->dev, "Operation Timed out\n");
>   	rc = -ETIME;
> -	goto out;
> +	goto out_rc;
>
>   out_recv:
>   	len = chip->ops->recv(chip, buf, bufsiz);
>   	if (len < 0) {
>   		rc = len;
> -		dev_err(&chip->dev,
> -			"tpm_transmit: tpm_recv: error %d\n", rc);
> -		goto out;
> -	} else if (len < TPM_HEADER_SIZE) {
> +		dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
> +	} else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
>   		rc = -EFAULT;
> -		goto out;
> -	}


Add an else branch here for 'rc = 0' because it is otherwise set from 
'rc = chip->ops->send(chip, buf, count);'. Or add it further above...