[UNIKRAFT PATCH 1/2] plat/virtio: virtio_config_get returns >= 0

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

The 9pfs driver fails to get the configuration when the
virtio_config_get returns a value greater than 0. The function
description on virtio_config_get was incorrect. The patches
changes the error check in the virtio-9p and the function
description

Signed-off-by: Sharan Santhanam <sharan.santhanam@xxxxxxxxx>
---
 plat/drivers/include/virtio/virtio_bus.h | 2 +-
 plat/drivers/virtio/virtio_9p.c          | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/plat/drivers/include/virtio/virtio_bus.h 
b/plat/drivers/include/virtio/virtio_bus.h
index 56f0dafe..b3bb8331 100644
--- a/plat/drivers/include/virtio/virtio_bus.h
+++ b/plat/drivers/include/virtio/virtio_bus.h
@@ -240,7 +240,7 @@ static inline void virtio_feature_set(struct virtio_dev 
*vdev, __u32 feature)
  * @param type_len
  *     The data type of the configuration data.
  * @return int
- *     0, on successful reading the configuration space.
+ *     >= 0, on successful reading the configuration space.
  *     < 0, on error.
  */
 static inline int virtio_config_get(struct virtio_dev *vdev, __u16 offset,
diff --git a/plat/drivers/virtio/virtio_9p.c b/plat/drivers/virtio/virtio_9p.c
index 045ce42f..7bd99b8d 100644
--- a/plat/drivers/virtio/virtio_9p.c
+++ b/plat/drivers/virtio/virtio_9p.c
@@ -347,7 +347,7 @@ static int virtio_9p_feature_negotiate(struct 
virtio_9p_device *d)
 
        if (virtio_config_get(d->vdev,
                          __offsetof(struct virtio_9p_config, tag_len),
-                         &tag_len, 1, sizeof(tag_len)))
+                         &tag_len, 1, sizeof(tag_len)) < 0)
        {
                rc = -EAGAIN;
                goto out;
-- 
2.20.1