virtio: Implementing attribute show with sysfs_emit

Replace sprintf with sysfs_emit or its variants for their
built-in PAGE_SIZE awareness.

Signed-off-by: Dawei Li <set_pte_at@outlook.com>
Message-Id: <TYCP286MB23232A999FE7DBDF50BA0FAACA0F9@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio.c

@@ -15,31 +15,31 @@ static ssize_t device_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%04x\n", dev->id.device);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.device);
 }
 static DEVICE_ATTR_RO(device);
 
 static ssize_t vendor_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%04x\n", dev->id.vendor);
+	return sysfs_emit(buf, "0x%04x\n", dev->id.vendor);
 }
 static DEVICE_ATTR_RO(vendor);
 
 static ssize_t status_show(struct device *_d,
 			   struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "0x%08x\n", dev->config->get_status(dev));
+	return sysfs_emit(buf, "0x%08x\n", dev->config->get_status(dev));
 }
 static DEVICE_ATTR_RO(status);
 
 static ssize_t modalias_show(struct device *_d,
 			     struct device_attribute *attr, char *buf)
 {
 	struct virtio_device *dev = dev_to_virtio(_d);
-	return sprintf(buf, "virtio:d%08Xv%08X\n",
+	return sysfs_emit(buf, "virtio:d%08Xv%08X\n",
 		       dev->id.device, dev->id.vendor);
 }
 static DEVICE_ATTR_RO(modalias);
@@ -54,9 +54,9 @@ static ssize_t features_show(struct device *_d,
 	/* We actually represent this as a bitstring, as it could be
 	 * arbitrary length in future. */
 	for (i = 0; i < sizeof(dev->features)*8; i++)
-		len += sprintf(buf+len, "%c",
+		len += sysfs_emit_at(buf, len, "%c",
 			       __virtio_test_bit(dev, i) ? '1' : '0');
-	len += sprintf(buf+len, "\n");
+	len += sysfs_emit_at(buf, len, "\n");
 	return len;
 }
 static DEVICE_ATTR_RO(features);