[PULL 12/15] vhost: Clean up how VhostOpts method vhost_get_config() fails

[Markus Armbruster <armbru@redhat.com>]

vhost_user_get_config() can fail without setting an error.  Unclean.
Its caller vhost_dev_get_config() compensates by substituting a
generic error then.  Goes back to commit 50de51387f "vhost:
Distinguish errors in vhost_dev_get_config()".

Clean up by moving the generic error from vhost_dev_get_config() to
all the failure paths that neglect to set an error.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210720125408.387910-13-armbru@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[Sign of error_setg_errno()'s second argument fixed in both calls]
---
 hw/virtio/vhost-user.c |  2 ++
 hw/virtio/vhost.c      | 10 ++--------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index aec6cc1990..229c114a19 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -2139,10 +2139,12 @@ static int vhost_user_get_config(struct vhost_dev *dev, uint8_t *config,
     msg.payload.config.offset = 0;
     msg.payload.config.size = config_len;
     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        error_setg_errno(errp, EPROTO, "vhost_get_config failed");
         return -EPROTO;
     }
 
     if (vhost_user_read(dev, &msg) < 0) {
+        error_setg_errno(errp, EPROTO, "vhost_get_config failed");
         return -EPROTO;
     }
 
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index dbbc6b6915..88f8a397dc 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1564,17 +1564,11 @@ void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
 int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
                          uint32_t config_len, Error **errp)
 {
-    ERRP_GUARD();
-    int ret;
-
     assert(hdev->vhost_ops);
 
     if (hdev->vhost_ops->vhost_get_config) {
-        ret = hdev->vhost_ops->vhost_get_config(hdev, config, config_len, errp);
-        if (ret < 0 && !*errp) {
-            error_setg_errno(errp, -ret, "vhost_get_config failed");
-        }
-        return ret;
+        return hdev->vhost_ops->vhost_get_config(hdev, config, config_len,
+                                                 errp);
     }
 
     error_setg(errp, "vhost_get_config not implemented");
-- 
2.31.1