On Mon, 1 Dec 2025 at 06:27, Mike Pattrick <[email protected]> wrote: > > On Wed, Nov 12, 2025 at 12:04 PM David Marchand <[email protected]> > wrote: >> >> A bug in the vhost library for VDUSE devices resulted in multi-segments >> mbufs being treated by OVS. >> >> This hard to debug situation resulted in incorrectly segmented packets >> with mlx5 nics, as the DPDK driver handles multi-segments mbufs fine >> even without requiring RTE_ETH_TX_OFFLOAD_MULTI_SEGS. >> >> While the bug is fixed in the vhost library, we could still hit similar >> situations with "normal" DPDK ports: for example, >> RTE_ETH_RX_OFFLOAD_SCATTER is requested for jumbo frames and a bug could >> be hidden there. >> >> Enforce only mono-segment mbufs are received. >> >> Link: >> https://patchwork.dpdk.org/project/dpdk/patch/[email protected]/ >> Reported-at: https://issues.redhat.com/browse/FDP-2121 >> Signed-off-by: David Marchand <[email protected]> >> --- >> lib/netdev-dpdk.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c >> index 3704145a57..0cb9fae9f0 100644 >> --- a/lib/netdev-dpdk.c >> +++ b/lib/netdev-dpdk.c >> @@ -2598,6 +2598,9 @@ netdev_dpdk_batch_init_packet_fields(struct >> dp_packet_batch *batch) >> struct dp_packet *packet; >> >> DP_PACKET_BATCH_FOR_EACH (i, packet, batch) { >> + /* Datapath does not support multi-segment buffers. */ >> + ovs_assert(packet->mbuf.nb_segs == 1); > > > Would this assert ever be hit in a case that wasn't a bug in a DPDK driver?
Nothing in OVS touches nb_segs, so it would be a bug coming from a DPDK component: a driver, the vhost library, the mempool/mbuf library.. -- David Marchand _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
