realtek: rtl93xx: fix incorrect destination port selection

When testing LLDP and STP, we observed that locally generated multicast
packets (e.g. LLDP, STP) were not restricted to the designated output
port(s). For example, when transmitting on `lan1`, the same packet was also
forwarded to other ports such as `lan2`.

Steps to reproduce:

1. Configure lldpd to use `lan1` in UCI and restart the service
2. Connect devices to `lan1` and `lan2`
3. Observe that the device on `lan2` still receives LLDP packets

The issue was caused by an incorrect `FWD_TYPE` setting in the TX CPU TAG,
which failed to enforce the selected egress port(s).

Fix this by updating the TX CPU TAG to set `FWD_TYPE` correctly, ensuring
that locally generated packets are transmitted only on the intended
port(s).

Signed-off-by: Issam Hamdi <ih@simonwunderlich.de>
Link: https://github.com/openwrt/openwrt/pull/19802
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
index ddfdabacb64627dc30eb0889491bdbd99d577836..10e4c2d0353ae276e7f870985406f15a3b907ee9 100644 (file)
--- a/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
+++ b/target/linux/realtek/files-6.12/drivers/net/ethernet/rtl838x_eth.c
@@ -156,7 +156,8 @@ static void rtl839x_create_tx_header(struct p_hdr *h, unsigned int dest_port, in
 static void rtl930x_create_tx_header(struct p_hdr *h, unsigned int dest_port, int prio)
 {
        h->cpu_tag[0] = 0x8000;  /* CPU tag marker */
-       h->cpu_tag[1] = h->cpu_tag[2] = 0;
+       h->cpu_tag[1] = 0x0200; /* Set FWD_TYPE to LOGICAL (2) */
+       h->cpu_tag[2] = 0;
        h->cpu_tag[3] = 0;
        h->cpu_tag[4] = 0;
        h->cpu_tag[5] = 0;
@@ -171,7 +172,8 @@ static void rtl930x_create_tx_header(struct p_hdr *h, unsigned int dest_port, in
 static void rtl931x_create_tx_header(struct p_hdr *h, unsigned int dest_port, int prio)
 {
        h->cpu_tag[0] = 0x8000;  /* CPU tag marker */
-       h->cpu_tag[1] = h->cpu_tag[2] = 0;
+       h->cpu_tag[1] = 0x0200; /* Set FWD_TYPE to LOGICAL (2) */
+       h->cpu_tag[2] = 0;
        h->cpu_tag[3] = 0;
        h->cpu_tag[4] = h->cpu_tag[5] = h->cpu_tag[6] = h->cpu_tag[7] = 0;
        if (dest_port >= 32) {