[PATCH] vhost: compilation fix for GCC-12

[Amit Prakash Shukla <amitprakashs@marvell.com>]

../lib/vhost/virtio_net.c:941:35: error:
		'buf_vec[0].buf_len' may be used uninitialized
		[-Werror=maybe-uninitialized]
  941 |         buf_len = buf_vec[vec_idx].buf_len;
      |                   ~~~~~~~~~~~~~~~~^~~~~~~~
../lib/vhost/virtio_net.c: In function 'virtio_dev_rx_packed':
../lib/vhost/virtio_net.c:1285:27: note: 'buf_vec' declared here
 1285 |         struct buf_vector buf_vec[BUF_VECTOR_MAX];
      |                           ^~~~~~~
cc1: all warnings being treated as errors

Fixes: 93520085efda ("vhost: add packed ring single enqueue")
Cc: stable@dpdk.org

Signed-off-by: Amit Prakash Shukla <amitprakashs@marvell.com>
---
 lib/vhost/virtio_net.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index b3d954aab4..0220bc923c 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -1069,6 +1069,12 @@ vhost_enqueue_single_packed(struct virtio_net *dev,
 	else
 		max_tries = 1;
 
+	/* To avoid GCC-12 warning.
+	 * GCC-12 is not evaluating sizeof at compile time.
+	 */
+	if (unlikely(size == 0))
+		return -1;
+
 	while (size > 0) {
 		/*
 		 * if we tried all available ring items, and still
@@ -1574,6 +1580,12 @@ vhost_enqueue_async_packed(struct virtio_net *dev,
 	else
 		max_tries = 1;
 
+	/* To avoid GCC-12 warning.
+	 * GCC-12 is not evaluating sizeof at compile time.
+	 */
+	if (unlikely(size == 0))
+		return -1;
+
 	while (size > 0) {
 		/*
 		 * if we tried all available ring items, and still
-- 
2.25.1