net/virtio: fix compilation with -Og

The compilation with gcc-6.3.0 and EXTRA_CFLAGS=-Og gives the following
error:

  CC virtio_rxtx.o
  virtio_rxtx.c: In function ‘virtio_rx_offload’:
  virtio_rxtx.c:680:10: error: ‘csum’ may be used uninitialized in
                        this function [-Werror=maybe-uninitialized]
       csum = ~csum;
       ~~~~~^~~~~~~

The function rte_raw_cksum_mbuf() may indeed return an error, and
in this case, csum won't be initialized. Fix it by initializing csum
to 0.

Fixes: 96cb6711939e ("net/virtio: support Rx checksum offload")
Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 609b413..2cf82fe 100644 (file)
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -670,7 +670,7 @@ virtio_rx_offload(struct rte_mbuf *m, struct virtio_net_hdr *hdr)
                         * In case of SCTP, this will be wrong since it's a CRC
                         * but there's nothing we can do.
                         */
-                       uint16_t csum, off;
+                       uint16_t csum = 0, off;
 
                        rte_raw_cksum_mbuf(m, hdr->csum_start,
                                rte_pktmbuf_pkt_len(m) - hdr->csum_start,