From 3384cc1162ebf360eea12be5b97f58fab40313c4 Mon Sep 17 00:00:00 2001
From: KKRainbow <5665404+KKRainbow@users.noreply.github.com>
Date: Fri, 16 Oct 2026 19:12:16 +0800
Subject: [PATCH] test: synchronize BPF veth initialization before sending
 (#2712)

---
 easytier/src/socket/fake_tcp/netfilter/linux_bpf.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/easytier/src/socket/fake_tcp/netfilter/linux_bpf.rs b/easytier/src/socket/fake_tcp/netfilter/linux_bpf.rs
index 4ae106cc..af6d9cd2 100644
--- a/easytier/src/socket/fake_tcp/netfilter/linux_bpf.rs
+++ b/easytier/src/socket/fake_tcp/netfilter/linux_bpf.rs
@@ -870,20 +870,28 @@ mod tests {
             let suffix = rand::thread_rng().gen_range(10000..99999);
             let capture_name = format!("elbc{suffix}");
             let sender_name = format!("elbs{suffix}");
+            // Assign MACs at creation so udev does not replace them after readback.
             run_ip(&[
                 "link",
                 "add",
                 &capture_name,
+                "address",
+                "02:00:00:00:00:01",
                 "type",
                 "veth",
                 "peer",
                 "name",
                 &sender_name,
+                "address",
+                "02:00:00:00:00:02",
             ])?;
 
             let setup_result = (|| {
                 run_ip(&["link", "set", "dev", &capture_name, "up"])?;
                 run_ip(&["link", "set", "dev", &sender_name, "up"])?;
+                // A single-device GETLINK synchronizes pending linkwatch work,
+                // activating the first endpoint's TX queue before any test sends.
+                run_ip(&["link", "show", "dev", &capture_name])?;
                 let interfaces = datalink::interfaces();
                 let find_mac = |name: &str| {
                     interfaces