On Tue, Aug 01, 2023 at 07:07:39PM -0600, David Ahern wrote:

On 8/1/23 4:07 PM, Andrew Kanner wrote:

quoted

@@ -1594,7 +1597,13 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
 	if (zerocopy)
 		return false;
 
-	if (SKB_DATA_ALIGN(len + TUN_RX_PAD) +
+	rcu_read_lock();
+	xdp_prog = rcu_dereference(tun->xdp_prog);
+	if (xdp_prog)
+		pad += XDP_PACKET_HEADROOM;
+	rcu_read_unlock();

since you do not care about the actual xdp_prog (only that one is set) I
believe you can use rcu_access_pointer here.

Good point. Thanks, David.

I'll resend both as v5.

The correct cc-list for PATCH 2/2 is also needed. It fixes
net/core/filter.c instead of drivers/net/tun.c now.

pw-bot: changes-requested

-- 
Andrew Kanner