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

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

[Jerin Jacob]

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: stable@dpdk.org
Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.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;
-- 
2.13.0

Re: [dpdk-stable] [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: stable@dpdk.org
> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

Reviewed-by: Maxime Coquelin <maxime.coquelin@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