net/virtio: fix build with 0 headroom

[ upstream commit c1ada9b ]

When using RTE_PKTMBUF_HEADROOM as 0, virito ethdev driver throws
compilation error
virtio_ethdev.c:1851:2: note: in expansion of macro ‘RTE_BUILD_BUG_ON’
RTE_BUILD_BUG_ON(RTE_PKTMBUF_HEADROOM
	< sizeof(struct virtio_net_hdr_mrg_rxbuf));

This patch change it into run-time check.

Bugzilla ID: 335
Fixes: dec08c2 ("virtio: check packet headroom at compile time")

Signed-off-by: Hemant Agrawal <hemant.agrawal@nxp.com>
Acked-by: Maxime Coquelin <maxime.coquelin@redhat.com>

drivers/net/virtio/virtio_ethdev.c

@@ -1665,7 +1665,14 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 	struct virtio_hw *hw = eth_dev->data->dev_private;
 	int ret;
 
-	RTE_BUILD_BUG_ON(RTE_PKTMBUF_HEADROOM < sizeof(struct virtio_net_hdr_mrg_rxbuf));
+	if (sizeof(struct virtio_net_hdr_mrg_rxbuf) > RTE_PKTMBUF_HEADROOM) {
+		PMD_INIT_LOG(ERR,
+			"Not sufficient headroom required = %d, avail = %d",
+			(int)sizeof(struct virtio_net_hdr_mrg_rxbuf),
+			RTE_PKTMBUF_HEADROOM);
+
+		return -1;
+	}
 
 	eth_dev->dev_ops = &virtio_eth_dev_ops;