Linux Virtualization - Aug 2011 - [PATCH 1/3] virtio-console: Use virtio_config_val() for retrieving config

This patch modifies virtio-console to use virtio_config_val() instead
of a 'if(virtio_has_feature()) vdev->config->get()' construct to
retrieve
optional values from the config space.

Cc: Amit Shah <amit.shah at redhat.com>
Cc: "Michael S. Tsirkin" <mst at redhat.com>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: virtualization at lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928 at gmail.com>
---
 drivers/char/virtio_console.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index fb68b12..ed99f3b 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1675,13 +1675,11 @@ static int __devinit virtcons_probe(struct virtio_device
*vdev)
 
 	multiport = false;
 	portdev->config.max_nr_ports = 1;
-	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+	if (virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
+			      offsetof(struct virtio_console_config,
+				       max_nr_ports),
+			      &portdev->config.max_nr_ports) == 0)
 		multiport = true;
-		vdev->config->get(vdev, offsetof(struct virtio_console_config,
-						 max_nr_ports),
-				  &portdev->config.max_nr_ports,
-				  sizeof(portdev->config.max_nr_ports));
-	}
 
 	err = init_vqs(portdev);
 	if (err < 0) {
-- 
1.7.6

This patch adds virtio_config_val_len() which allows retrieving variable
length data from the virtio config space only if a specific feature is on.

Cc: Amit Shah <amit.shah at redhat.com>
Cc: "Michael S. Tsirkin" <mst at redhat.com>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: virtualization at lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928 at gmail.com>
---
 include/linux/virtio_config.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 39c88c5..add4790 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -155,6 +155,9 @@ static inline bool virtio_has_feature(const struct
virtio_device *vdev,
 #define virtio_config_val(vdev, fbit, offset, v) \
 	virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
 
+#define virtio_config_val_len(vdev, fbit, offset, v, len) \
+	virtio_config_buf((vdev), (fbit), (offset), (v), (len))
+
 static inline int virtio_config_buf(struct virtio_device *vdev,
 				    unsigned int fbit,
 				    unsigned int offset,
-- 
1.7.6

This patch modifies virtio-net to use virtio_config_val() instead
of a 'if(virtio_has_feature()) vdev->config->get()' construct to
retrieve
optional values from the config space.

Cc: Amit Shah <amit.shah at redhat.com>
Cc: "Michael S. Tsirkin" <mst at redhat.com>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: virtualization at lists.linux-foundation.org
Signed-off-by: Sasha Levin <levinsasha928 at gmail.com>
---
 drivers/net/virtio_net.c |   14 +++++---------
 1 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0c7321c..878db50 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -902,12 +902,10 @@ static void virtnet_update_status(struct virtnet_info *vi)
 {
 	u16 v;
 
-	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS))
-		return;
-
-	vi->vdev->config->get(vi->vdev,
+	if (virtio_config_val(vi->vdev, VIRTIO_NET_F_STATUS,
 			      offsetof(struct virtio_net_config, status),
-			      &v, sizeof(v));
+			      &v) < 0)
+		return;
 
 	/* Ignore unknown (future) status bits */
 	v &= VIRTIO_NET_S_LINK_UP;
@@ -982,11 +980,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 	}
 
 	/* Configuration may specify what MAC to use.  Otherwise random. */
-	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
-		vdev->config->get(vdev,
+	if (virtio_config_val_len(vdev, VIRTIO_NET_F_MAC,
 				  offsetof(struct virtio_net_config, mac),
-				  dev->dev_addr, dev->addr_len);
-	} else
+				  dev->dev_addr, dev->addr_len) < 0)
 		random_ether_addr(dev->dev_addr);
 
 	/* Set up our device-specific information */
-- 
1.7.6