diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 8839133d6f6b..004e651e6067 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -61,7 +61,11 @@ struct request_sock {
 	struct request_sock		*dl_next;
 	u16				mss;
 	u8				num_retrans; /* number of retransmits */
-	u8				syncookie:1; /* syncookie: encode tcpopts in timestamp */
+	u8				syncookie:1; /* True if
+						      * 1) tcpopts needs to be encoded in
+						      *    TS of SYN+ACK
+						      * 2) ACK is validated by BPF kfunc.
+						      */
 	u8				num_timeout:7; /* number of timeouts */
 	u32				ts_recent;
 	struct timer_list		rsk_timer;
@@ -144,6 +148,7 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
 	sk_node_init(&req_to_sk(req)->sk_node);
 	sk_tx_queue_clear(req_to_sk(req));
 	req->saved_syn = NULL;
+	req->syncookie = 0;
 	req->timeout = 0;
 	req->num_timeout = 0;
 	req->num_retrans = 0;
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 7972ad3d7c73..500f665f98cb 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -474,6 +474,9 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 				  ireq->wscale_ok, &rcv_wscale,
 				  dst_metric(&rt->dst, RTAX_INITRWND));
 
+	/* req->syncookie is set true only if ACK is validated
+	 * by BPF kfunc, then, rcv_wscale is already configured.
+	 */
 	if (!req->syncookie)
 		ireq->rcv_wscale = rcv_wscale;
 	ireq->ecn_ok &= cookie_ecn_ok(net, &rt->dst);
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 8bad0a44a0a6..6d8286c299c9 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -258,6 +258,9 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 				  ireq->wscale_ok, &rcv_wscale,
 				  dst_metric(dst, RTAX_INITRWND));
 
+	/* req->syncookie is set true only if ACK is validated
+	 * by BPF kfunc, then, rcv_wscale is already configured.
+	 */
 	if (!req->syncookie)
 		ireq->rcv_wscale = rcv_wscale;
 	ireq->ecn_ok &= cookie_ecn_ok(net, dst);