On Fri Sep 13, 2024 at 11:05 PM EEST, Ross Philipson wrote:
> From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>
>
> The function tpm_tis_request_locality() is expected to return the locality
> value that was requested, or a negative error code upon failure. If it is called
> while locality_count of struct tis_data is non-zero, no actual locality request
> will be sent. Because the ret variable is initially set to 0, the
> locality_count will still get increased, and the function will return 0. For a
> caller, this would indicate that locality 0 was successfully requested and not
> the state changes just mentioned.
>
> Additionally, the function __tpm_tis_request_locality() provides inconsistent
> error codes. It will provide either a failed IO write or a -1 should it have
> timed out waiting for locality request to succeed.
>
> This commit changes __tpm_tis_request_locality() to return valid negative error
> codes to reflect the reason it fails. It then adjusts the return value check in
> tpm_tis_request_locality() to check for a non-negative return value before
> incrementing locality_cout. In addition, the initial value of the ret value is
> set to a negative error to ensure the check does not pass if
> __tpm_tis_request_locality() is not called.
>
> Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ross Philipson <ross.philipson@xxxxxxxxxx>
> ---
> drivers/char/tpm/tpm_tis_core.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 22ebf679ea69..20a8b341be0d 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -210,7 +210,7 @@ static int __tpm_tis_request_locality(struct tpm_chip *chip, int l)
> again:
> timeout = stop - jiffies;
> if ((long)timeout <= 0)
> - return -1;
> + return -EBUSY;
> rc = wait_event_interruptible_timeout(priv->int_queue,
> (check_locality
> (chip, l)),
> @@ -229,18 +229,21 @@ static int __tpm_tis_request_locality(struct tpm_chip *chip, int l)
> tpm_msleep(TPM_TIMEOUT);
> } while (time_before(jiffies, stop));
> }
> - return -1;
> + return -EBUSY;
> }
>
> static int tpm_tis_request_locality(struct tpm_chip *chip, int l)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> - int ret = 0;
> + int ret = -EBUSY;
> +
> + if (l < 0 || l > TPM_MAX_LOCALITY)
> + return -EINVAL;
>
> mutex_lock(&priv->locality_count_mutex);
> if (priv->locality_count == 0)
> ret = __tpm_tis_request_locality(chip, l);
> - if (!ret)
> + if (ret >= 0)
> priv->locality_count++;
> mutex_unlock(&priv->locality_count_mutex);
> return ret;
First of all, -1 is as consistent value as a value can be.
Secondly:
if (tpm_tis_request_locality(chip, 0) != 0)
return -EBUSY;
What am I missing here?
BR, Jarkko
