svn commit: r362186 - head/sys/dev/virtio/network

[Jessica Clarke]

Author: jrtc27
Date: Sun Jun 14 22:39:34 2020
New Revision: 362186
URL: https://svnweb.freebsd.org/changeset/base/362186

Log:
  vtnet: Fix regression introduced in r361944
  
  For legacy devices that don't support MrgRxBuf (such as bhyve pre-r358180),
  r361944 failed to update the receive handler to account for the additional
  padding introduced by the unused num_buffers field that is now always present
  in struct vtnet_rx_header. Thus, calculate the padding dynamically based on
  vtnet_hdr_size.
  
  PR:		247242
  Reported by:	thj
  Tested by:	thj

Modified:
  head/sys/dev/virtio/network/if_vtnet.c

Modified: head/sys/dev/virtio/network/if_vtnet.c
==============================================================================
--- head/sys/dev/virtio/network/if_vtnet.c	Sun Jun 14 21:07:12 2020	(r362185)
+++ head/sys/dev/virtio/network/if_vtnet.c	Sun Jun 14 22:39:34 2020	(r362186)
@@ -1819,9 +1819,10 @@ vtnet_rxq_eof(struct vtnet_rxq *rxq)
 			adjsz = sizeof(struct vtnet_rx_header);
 			/*
 			 * Account for our pad inserted between the header
-			 * and the actual start of the frame.
+			 * and the actual start of the frame. This includes
+			 * the unused num_buffers when using a legacy device.
 			 */
-			len += VTNET_RX_HEADER_PAD;
+			len += adjsz - sc->vtnet_hdr_size;
 		} else {
 			mhdr = mtod(m, struct virtio_net_hdr_mrg_rxbuf *);
 			nbufs = mhdr->num_buffers;