Hi Jonathan,
On 05.03.25 10:45, Jonathan McDowell wrote:
> From: Jonathan McDowell <nood...@meta.com>
>
> The change to only use interrupts to handle supported status changes,
> then switch to polling for the rest, inverted the status test and sleep
> such that we can end up sleeping beyond our timeout and not actually
> checking the status. This can result in spurious TPM timeouts,
> especially on a more loaded system. Fix by switching the order back so
> we sleep *then* check. We've done a up front check when we enter the
> function so this won't cause an additional delay when the status is
> already what we're looking for.
>
> Cc: sta...@vger.kernel.org # v6.4+
> Fixes: e87fcf0dc2b4 ("tpm, tpm_tis: Only handle supported interrupts")
> Signed-off-by: Jonathan McDowell <nood...@meta.com>
> Reviewed-by: Michal Suchánek <msucha...@suse.de>
> ---
> drivers/char/tpm/tpm_tis_core.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index fdef214b9f6b..167d71747666 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -114,11 +114,11 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8
> mask,
> return 0;
> /* process status changes without irq support */
> do {
> + usleep_range(priv->timeout_min,
> + priv->timeout_max);
> status = chip->ops->status(chip);
> if ((status & mask) == mask)
> return 0;
> - usleep_range(priv->timeout_min,
> - priv->timeout_max);
> } while (time_before(jiffies, stop));
> return -ETIME;
> }
> --
> 2.48.1
>
FWIW:
Reviewed-by: Lino Sanfilippo <l.sanfili...@kunbus.com>
I cannot remember any more but I think the change of the logic in
the while loop must have been a leftover from some tests I did
at this time. However it should not have been part of the patch, so
good that you found it and thanks for the fix!
BR,
Lino
