[PATCH 5.11 075/210] net: hsr: Reset MAC header for Tx path

Greg Kroah-Hartman
2021-04-12T09:31:06Z

From: Kurt Kanzenbach <kurt@linutronix.de>

commit 9d6803921a16f4d768dc41a75375629828f4d91e upstream.

Reset MAC header in HSR Tx path. This is needed, because direct packet
transmission, e.g. by specifying PACKET_QDISC_BYPASS does not reset the MAC
header.

This has been observed using the following setup:

|$ ip link add name hsr0 type hsr slave1 lan0 slave2 lan1 supervision 45 version 1
|$ ifconfig hsr0 up
|$ ./test hsr0

The test binary is using mmap'ed sockets and is specifying the
PACKET_QDISC_BYPASS socket option.

This patch resolves the following warning on a non-patched kernel:

|[ 112.725394] ------------[ cut here ]------------
|[ 112.731418] WARNING: CPU: 1 PID: 257 at net/hsr/hsr_forward.c:560 hsr_forward_skb+0x484/0x568
|[ 112.739962] net/hsr/hsr_forward.c:560: Malformed frame (port_src hsr0)

The warning can be safely removed, because the other call sites of
hsr_forward_skb() make sure that the skb is prepared correctly.

Fixes: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/hsr/hsr_device.c | 1 +
net/hsr/hsr_forward.c | 6 ------
2 files changed, 1 insertion(+), 6 deletions(-)

--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -217,6 +217,7 @@ static netdev_tx_t hsr_dev_xmit(struct s
master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
if (master) {
skb->dev = master->dev;
+ skb_reset_mac_header(skb);
hsr_forward_skb(skb, master);
} else {
atomic_long_inc(&dev->tx_dropped);
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -528,12 +528,6 @@ void hsr_forward_skb(struct sk_buff *skb
{
struct hsr_frame_info frame;

- if (skb_mac_header(skb) != skb->data) {
- WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n",
- __FILE__, __LINE__, port->dev->name);
- goto out_drop;
- }
-
if (fill_frame_info(&frame, skb, port) < 0)
goto out_drop;