[dpdk-dev] [PATCH v4] net/virtio: fix wrong variable assignment in helper macro

[Vipul Ashri <vipul.ashri@oracle.com>]

Inside Macro ASSIGN_UNLESS_EQUAL(var, val), assignment to var is always
failing as assignment done using var_ having local scope only.
This leads to TX packets not going out and found broken due to cleanup
malfunctioning. This patch fixes the wrong variable assignment.

Fixes: 57f90f894588 ("net/virtio: reuse packed ring functions")
Cc: stable@dpdk.org

Signed-off-by: Vipul Ashri <vipul.ashri@oracle.com>
---
 drivers/net/virtio/virtqueue.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 105a9c00c..7f8a3976f 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -607,10 +607,11 @@ virtqueue_notify(struct virtqueue *vq)
 
 /* avoid write operation when necessary, to lessen cache issues */
 #define ASSIGN_UNLESS_EQUAL(var, val) do {	\
-	typeof(var) var_ = (var);		\
-	typeof(val) val_ = (val);		\
-	if ((var_) != (val_))			\
-		(var_) = (val_);		\
+	typeof(var) *const var_ = &(var);	\
+	typeof(val)  const val_ = (val);	\
+	if (*var_ != val_)			\
+		*var_ = val_;			\
+
 } while (0)
 
 #define virtqueue_clear_net_hdr(hdr) do {		\
-- 
2.28.0.windows.1