s390/crypto: use scnprintf() instead of snprintf()

snprintf() returns the number of bytes that would be written,
which may be greater than the the actual length to be written.

show() methods should return the number of bytes printed into the
buffer. This is the return value of scnprintf().

Link: https://lkml.kernel.org/r/20200509085608.41061-2-chenzhou10@huawei.comSigned-off-by: Chen Zhou <chenzhou10@huawei.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/crypto/prng.c

@@ -693,7 +693,7 @@ static ssize_t prng_chunksize_show(struct device *dev,
 				   struct device_attribute *attr,
 				   char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
+	return scnprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
 }
 static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
 
@@ -712,7 +712,7 @@ static ssize_t prng_counter_show(struct device *dev,
 		counter = prng_data->prngws.byte_counter;
 	mutex_unlock(&prng_data->mutex);
 
-	return snprintf(buf, PAGE_SIZE, "%llu\n", counter);
+	return scnprintf(buf, PAGE_SIZE, "%llu\n", counter);
 }
 static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
 
@@ -721,7 +721,7 @@ static ssize_t prng_errorflag_show(struct device *dev,
 				   struct device_attribute *attr,
 				   char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
+	return scnprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
 }
 static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
 
@@ -731,9 +731,9 @@ static ssize_t prng_mode_show(struct device *dev,
 			      char *buf)
 {
 	if (prng_mode == PRNG_MODE_TDES)
-		return snprintf(buf, PAGE_SIZE, "TDES\n");
+		return scnprintf(buf, PAGE_SIZE, "TDES\n");
 	else
-		return snprintf(buf, PAGE_SIZE, "SHA512\n");
+		return scnprintf(buf, PAGE_SIZE, "SHA512\n");
 }
 static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
 
@@ -756,7 +756,7 @@ static ssize_t prng_reseed_limit_show(struct device *dev,
 				      struct device_attribute *attr,
 				      char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
+	return scnprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
 }
 static ssize_t prng_reseed_limit_store(struct device *dev,
 				       struct device_attribute *attr,
@@ -787,7 +787,7 @@ static ssize_t prng_strength_show(struct device *dev,
 				  struct device_attribute *attr,
 				  char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "256\n");
+	return scnprintf(buf, PAGE_SIZE, "256\n");
 }
 static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);