Re: [PATCH v3 06/16] tpm: clean up tpm_try_transmit() error handling flow

Stefan Berger
2018-11-05T22:20:42Z

On 11/4/18 8:45 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@linux.intel.com>
> ---
> drivers/char/tpm/tpm-interface.c | 90 ++++++++++++++------------------
> 1 file changed, 39 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index ecda6f96cde0..0f343407daf8 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -171,7 +171,6 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> ssize_t len = 0;
> u32 count, ordinal;
> unsigned long stop;
> - bool need_locality;
>
> rc = tpm_validate_command(chip, space, buf, bufsiz);
> if (rc == -EINVAL)
> @@ -201,30 +200,9 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> 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);

tpm2_prepare_space() may issue TPM commands itself. Following your tree
the move should now put the clk_enable() and tpm_request_locality() in
the path. So, looks good.

> if (rc)
> - goto out_idle;
> + return rc;
>
> rc = chip->ops->send(chip, buf, count);
> if (rc < 0) {
> @@ -265,40 +243,16 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
> rc = len;
> dev_err(&chip->dev,
> "tpm_transmit: tpm_recv: error %d\n", rc);
> - goto out_idle;
> - } else if (len < TPM_HEADER_SIZE) {
> - rc = -EFAULT;
> - goto out_idle;
> - }
> -
> - if (len != be32_to_cpu(header->length)) {
> + tpm2_flush_space(chip);
> + } else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
> rc = -EFAULT;
> - goto out_idle;
> - }
>
> out_space:
> - if (rc) {
> + if (rc)
> tpm2_flush_space(chip);
> - } else {
> + else
> rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
> - if (rc)
> - dev_err(&chip->dev, "tpm2_commit_space: error %d\n",
> - rc);

This should have been removed in the previous patch...

> - }
> -
> -out_idle:
> - /* may fail but do not override previous error value in rc */
> - tpm_go_idle(chip, flags);
> -
> -out_locality:
> - if (need_locality)
> - tpm_relinquish_locality(chip, flags);
> -
> - if (chip->ops->clk_enable != NULL)
> - chip->ops->clk_enable(chip, false);
>
> - if (!(flags & TPM_TRANSMIT_UNLOCKED) && !(flags & TPM_TRANSMIT_NESTED))
> - mutex_unlock(&chip->tpm_mutex);
> return rc ? rc : len;
> }
>
> @@ -328,6 +282,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
> /* space for header and handles */
> u8 save[TPM_HEADER_SIZE + 3*sizeof(u32)];
> unsigned int delay_msec = TPM2_DURATION_SHORT;
> + bool has_locality = false;
> u32 rc = 0;
> ssize_t ret;
> const size_t save_size = min(space ? sizeof(save) : TPM_HEADER_SIZE,
> @@ -343,7 +298,40 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
> memcpy(save, buf, save_size);
>
> for (;;) {
> + 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);
> +
> + if (chip->locality == -1) {
> + ret = tpm_request_locality(chip, flags);
> + if (ret)
> + goto out_locality;
> + has_locality = true;
> + }
> +
> + ret = tpm_cmd_ready(chip, flags);
> + if (ret)
> + goto out_locality;
> +
> ret = tpm_try_transmit(chip, space, buf, bufsiz, flags);
> +
> + /* This may fail but do not override ret. */
> + tpm_go_idle(chip, flags);
> +
> +out_locality:
> + if (has_locality)
> + tpm_relinquish_locality(chip, flags);

Safer to also put has_locality = false here ?

> +
> + if (chip->ops->clk_enable != NULL)
> + chip->ops->clk_enable(chip, false);
> +
> + if (!(flags & TPM_TRANSMIT_UNLOCKED) &&
> + !(flags & TPM_TRANSMIT_NESTED))
> + mutex_unlock(&chip->tpm_mutex);
> +
> if (ret < 0)
> break;
> rc = be32_to_cpu(header->return_code);