On Mon, Oct 19, 2020 at 04:17:59PM -0700, Jerry Snitselaar wrote:
>
> James Bottomley @ 2020-10-01 11:09 MST:
>
> > The current release locality code seems to be based on the
> > misunderstanding that the TPM interrupts when a locality is released:
> > it doesn't, only when the locality is acquired.
> >
> > Furthermore, there seems to be no point in waiting for the locality to
> > be released. All it does is penalize the last TPM user. However, if
> > there's no next TPM user, this is a pointless wait and if there is a
> > next TPM user, they'll pay the penalty waiting for the new locality
> > (or possibly not if it's the same as the old locality).
> >
> > Fix the code by making release_locality as simple write to release
> > with no waiting for completion.
> >
> > Fixes: 33bafe90824b ("tpm_tis: verify locality released before returning from release_locality")
> > Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> >
> > ---
> >
> > v2: added fixes
> > ---
> > drivers/char/tpm/tpm_tis_core.c | 47 +--------------------------------
> > 1 file changed, 1 insertion(+), 46 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> > index f3ecde8df47d..431919d5f48a 100644
> > --- a/drivers/char/tpm/tpm_tis_core.c
> > +++ b/drivers/char/tpm/tpm_tis_core.c
> > @@ -135,58 +135,13 @@ static bool check_locality(struct tpm_chip *chip, int l)
> > return false;
> > }
> >
> > -static bool locality_inactive(struct tpm_chip *chip, int l)
> > -{
> > - struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > - int rc;
> > - u8 access;
> > -
> > - rc = tpm_tis_read8(priv, TPM_ACCESS(l), &access);
> > - if (rc < 0)
> > - return false;
> > -
> > - if ((access & (TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY))
> > - == TPM_ACCESS_VALID)
> > - return true;
> > -
> > - return false;
> > -}
> > -
> > static int release_locality(struct tpm_chip *chip, int l)
> > {
> > struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > - unsigned long stop, timeout;
> > - long rc;
> >
> > tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
> >
> > - stop = jiffies + chip->timeout_a;
> > -
> > - if (chip->flags & TPM_CHIP_FLAG_IRQ) {
> > -again:
> > - timeout = stop - jiffies;
> > - if ((long)timeout <= 0)
> > - return -1;
> > -
> > - rc = wait_event_interruptible_timeout(priv->int_queue,
> > - (locality_inactive(chip, l)),
> > - timeout);
> > -
> > - if (rc > 0)
> > - return 0;
> > -
> > - if (rc == -ERESTARTSYS && freezing(current)) {
> > - clear_thread_flag(TIF_SIGPENDING);
> > - goto again;
> > - }
> > - } else {
> > - do {
> > - if (locality_inactive(chip, l))
> > - return 0;
> > - tpm_msleep(TPM_TIMEOUT);
> > - } while (time_before(jiffies, stop));
> > - }
> > - return -1;
> > + return 0;
> > }
> >
> > static int request_locality(struct tpm_chip *chip, int l)
>
> Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
/Jarkko
