[openwrt/openwrt] wireguard-tools: enable reload without teardown

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch openwrt-25.12:
https://git.openwrt.org/436b090bc746441a658524a84b9e35afe468ec35

commit 436b090bc746441a658524a84b9e35afe468ec35
Author: Paul Donald <newtwen+github at gmail.com>
AuthorDate: Sat Jan 31 15:52:21 2026 +0100

    wireguard-tools: enable reload without teardown
    
    - preserve (active) interface (at reload)
    
    Signed-off-by: Paul Donald <newtwen+github at gmail.com>
    Link: https://github.com/openwrt/openwrt/pull/21784
    Signed-off-by: Robert Marko <robimarko at gmail.com>
    (cherry picked from commit 0a576dec7468b9d1185b383ba17ee9c7b2151a5d)
    Link: https://github.com/openwrt/openwrt/pull/21840
    Signed-off-by: Hauke Mehrtens <hauke at hauke-m.de>
---
 package/network/utils/wireguard-tools/files/wireguard.sh | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/package/network/utils/wireguard-tools/files/wireguard.sh b/package/network/utils/wireguard-tools/files/wireguard.sh
index e8867d65f7..738714e1c6 100644
--- a/package/network/utils/wireguard-tools/files/wireguard.sh
+++ b/package/network/utils/wireguard-tools/files/wireguard.sh
@@ -56,12 +56,10 @@ proto_wireguard_setup() {
 	config_get nohostroute "${config}" "nohostroute"
 	config_get tunlink "${config}" "tunlink"
 
-	ip link del dev "${config}" 2>/dev/null
-	ip link add dev "${config}" type wireguard
+	# Add the link only if it didn't already exist
+	ip -br link show "${config}" >/dev/null 2>&1 || ip link add dev "${config}" type wireguard
 
-	if [ "${mtu}" ]; then
-		ip link set mtu "${mtu}" dev "${config}"
-	fi
+	[ -n "${mtu}" ] && ip link set mtu "${mtu}" dev "${config}"
 
 	proto_init_update "${config}" 1