build/external/patches/dpdk_20.08/0001-net-virtio-fix-variable-assignment-in-helper-macro.patch

From a1412e05caa2678757156d4de2755ab5140ecc24 Mon Sep 17 00:00:00 2001
From: Vipul Ashri <vipul.ashri@oracle.com>
Date: Fri, 18 Sep 2020 15:25:04 +0530
Subject: [PATCH] net/virtio: fix variable assignment in helper macro

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>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 drivers/net/virtio/virtqueue.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 105a9c00c..6ed50648c 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -607,10 +607,10 @@ 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 {		\
-- 
2.18.4