Re: [dpdk-dev] [PATCH 4/4] examples/vhost: fix uninitialized desc indexes

[Maxime Coquelin]

On 06/02/2017 01:20 PM, Jerin Jacob wrote:

Fixing the below error by returning from the function early
when count == 0.

Issue flagged by GCC 7.1.1

examples/vhost/virtio_net.c:370:38: error: ‘desc_indexes[0]’ may be used
uninitialized in this function [-Werror=maybe-uninitialized]
   rte_prefetch0(&vr->desc[desc_indexes[0]]);

Fixes: ca059fa5e290 ("examples/vhost: demonstrate the new generic APIs")

Cc: sta...@dpdk.org
Signed-off-by: Jerin Jacob <jerin.ja...@caviumnetworks.com>

Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>

---
  examples/vhost/virtio_net.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/examples/vhost/virtio_net.c b/examples/vhost/virtio_net.c
index cc2c3d882..5e1ed44a5 100644
--- a/examples/vhost/virtio_net.c
+++ b/examples/vhost/virtio_net.c
@@ -350,6 +350,9 @@ vs_dequeue_pkts(struct vhost_dev *dev, uint16_t queue_id,
        count = RTE_MIN(count, MAX_PKT_BURST);
        count = RTE_MIN(count, free_entries);

+ if (unlikely(count == 0))

+               return 0;
+
        /*
         * Retrieve all of the head indexes first and pre-update used entries
         * to avoid caching issues.
@@ -385,8 +388,6 @@ vs_dequeue_pkts(struct vhost_dev *dev, uint16_t queue_id,
                }

}

-       if (!i)
-               return 0;

queue->last_avail_idx += i;

        queue->last_used_idx += i;

Thanks,
Maxime