Author: vmaffione
Date: Mon Jun 1 16:14:29 2020
New Revision: 361698
URL: https://svnweb.freebsd.org/changeset/base/361698
Log:
netmap: if_vtnet: avoid netmap ring wraparound
netmap assumes the one "slot" is left unused to distinguish
the empty ring and full ring conditions. This assumption was
violated by vtnet_netmap_rxq_populate().
MFC after: 1 week
Modified:
head/sys/dev/netmap/if_vtnet_netmap.h
Modified: head/sys/dev/netmap/if_vtnet_netmap.h
==============================================================================
--- head/sys/dev/netmap/if_vtnet_netmap.h Mon Jun 1 16:12:09 2020
(r361697)
+++ head/sys/dev/netmap/if_vtnet_netmap.h Mon Jun 1 16:14:29 2020
(r361698)
@@ -275,8 +275,8 @@ vtnet_netmap_rxq_populate(struct vtnet_rxq *rxq)
/* Expose all the RX netmap buffers we can. In case of no indirect
* buffers, the number of netmap slots in the RX ring matches the
* maximum number of 2-elements sglist that the RX virtqueue can
- * accommodate. */
- error = vtnet_netmap_kring_refill(kring, na->num_rx_desc);
+ * accommodate (minus 1 to avoid netmap ring wraparound). */
+ error = vtnet_netmap_kring_refill(kring, na->num_rx_desc - 1);
virtqueue_notify(rxq->vtnrx_vq);
return error < 0 ? ENXIO : 0;
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
