tpm: return 0 from pcrs_show() when tpm1_pcr_read() fails

Do not print partial list of PCRs when tpm1_pcr_read() fails but instead
return 0 from pcrs_show(). This is consistent behavior with other sysfs
functions.
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: Alexander Steffen <Alexander.Steffen@infineon.com>

drivers/char/tpm/tpm-sysfs.c

@@ -100,22 +100,21 @@ static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
 {
 	cap_t cap;
 	u8 digest[TPM_DIGEST_SIZE];
-	ssize_t rc;
 	u32 i, j, num_pcrs;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
 
-	rc = tpm1_getcap(chip, TPM_CAP_PROP_PCR, &cap,
+	if (tpm1_getcap(chip, TPM_CAP_PROP_PCR, &cap,
 			"attempting to determine the number of PCRS",
-			 sizeof(cap.num_pcrs));
-	if (rc)
+			sizeof(cap.num_pcrs)))
 		return 0;
 
 	num_pcrs = be32_to_cpu(cap.num_pcrs);
 	for (i = 0; i < num_pcrs; i++) {
-		rc = tpm1_pcr_read(chip, i, digest);
-		if (rc)
+		if (tpm1_pcr_read(chip, i, digest)) {
+			str = buf;
 			break;
+		}
 		str += sprintf(str, "PCR-%02d: ", i);
 		for (j = 0; j < TPM_DIGEST_SIZE; j++)
 			str += sprintf(str, "%02X ", digest[j]);