vhost: track zero copy failures using DMA length

This will be used to disable zerocopy when error rate
is high.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index b6538eef7468..464469d901d5 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -17,6 +17,8 @@
  * For transmit, used buffer len is unused; we override it to track buffer
  * status internally; used for zerocopy tx only.
  */
+/* Lower device DMA failed */
+#define VHOST_DMA_FAILED_LEN    3
 /* Lower device DMA done */
 #define VHOST_DMA_DONE_LEN      2
 /* Lower device DMA in progress */
@@ -24,6 +26,8 @@
 /* Buffer unused */
 #define VHOST_DMA_CLEAR_LEN     0
 
+#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
+
 struct vhost_device;
 
 struct vhost_work;