tpm, tpm_tis: Fix timeout handling when waiting for TPM status

commit 7146dffa875cd00e7a7f918e1fce79c7593ac1fa upstream.

The change to only use interrupts to handle supported status changes
introduced an issue when it is necessary to poll for the status. Rather
than checking for the status after sleeping the code now sleeps after
the check. This means a correct, but slower, status change on the part
of the TPM can be missed, resulting in a spurious timeout error,
especially on a more loaded system. Switch back to sleeping *then*
checking. An up front check of the status has been done at the start of
the function, so this does not cause an additional delay when the status
is already what we're looking for.

Cc: stable@vger.kernel.org # v6.4+
Fixes: e87fcf0dc2b4 ("tpm, tpm_tis: Only handle supported interrupts")
Signed-off-by: Jonathan McDowell <noodles@meta.com>
Reviewed-by: Michal Suchánek <msuchanek@suse.de>
Reviewed-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 4cc2ab2d16cc5eefd38cd3124ed1a7890f736367..ed0d3d8449b306ae07cc9b85b6cfbd854351ff4e 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -114,11 +114,10 @@ again:
                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;
 }