tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations

commit db4d8cb9c9f2af71c4d087817160d866ed572cc9 upstream

TPM 2.0 Shutdown involve sending TPM2_Shutdown to TPM chip and disabling
future TPM operations. TPM 1.2 behavior was different, future TPM
operations weren't disabled, causing rare issues. This patch ensures
that future TPM operations are disabled.

Fixes: d1bd4a792d39 ("tpm: Issue a TPM2_Shutdown for TPM2 devices.")
Cc: stable@vger.kernel.org
Signed-off-by: Vadim Sukhomlinov <sukhomlinov@google.com>
[dianders: resolved merge conflicts with mainline]
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/char/tpm/tpm-chip.c

@@ -187,12 +187,13 @@ static int tpm_class_shutdown(struct device *dev)
 {
 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 
+	down_write(&chip->ops_sem);
 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		down_write(&chip->ops_sem);
 		tpm2_shutdown(chip, TPM2_SU_CLEAR);
 		chip->ops = NULL;
-		up_write(&chip->ops_sem);
 	}
+	chip->ops = NULL;
+	up_write(&chip->ops_sem);
 
 	return 0;
 }