[PATCH 5.10 032/120] r8169: work around RTL8125 UDP hw bug

Greg Kroah-Hartman
2021-02-08T17:14:55Z

From: Heiner Kallweit <hkallweit1@gmail.com>

[ Upstream commit 8d520b4de3edca4f4fb242b5ddc659b6a9b9e65e ]

It was reported that on RTL8125 network breaks under heavy UDP load,
e.g. torrent traffic ([0], from comment 27). Realtek confirmed a hw bug
and provided me with a test version of the r8125 driver including a
workaround. Tests confirmed that the workaround fixes the issue.
I modified the original version of the workaround to meet mainline
code style.

[0] https://bugzilla.kernel.org/show_bug.cgi?id=209839

v2:
- rebased to net
v3:
- make rtl_skb_is_udp() more robust and use skb_header_pointer()
to access the ip(v6) header
v4:
- remove dependency on ptp_classify.h
- replace magic number with offsetof(struct udphdr, len)

Fixes: f1bce4ad2f1c ("r8169: add support for RTL8125")
Tested-by: xplo <xplo.bn@gmail.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/6e453d49-1801-e6de-d5f7-d7e6c7526c8f@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/realtek/r8169_main.c | 71 +++++++++++++++++++++--
1 file changed, 65 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 762cabf16157b..64b77d415a525 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4082,17 +4082,72 @@ err_out:
return -EIO;
}

-static bool rtl_test_hw_pad_bug(struct rtl8169_private *tp)
+static bool rtl_skb_is_udp(struct sk_buff *skb)
+{
+ int no = skb_network_offset(skb);
+ struct ipv6hdr *i6h, _i6h;
+ struct iphdr *ih, _ih;
+
+ switch (vlan_get_protocol(skb)) {
+ case htons(ETH_P_IP):
+ ih = skb_header_pointer(skb, no, sizeof(_ih), &_ih);
+ return ih && ih->protocol == IPPROTO_UDP;
+ case htons(ETH_P_IPV6):
+ i6h = skb_header_pointer(skb, no, sizeof(_i6h), &_i6h);
+ return i6h && i6h->nexthdr == IPPROTO_UDP;
+ default:
+ return false;
+ }
+}
+
+#define RTL_MIN_PATCH_LEN 47
+
+/* see rtl8125_get_patch_pad_len() in r8125 vendor driver */
+static unsigned int rtl8125_quirk_udp_padto(struct rtl8169_private *tp,
+ struct sk_buff *skb)
{
+ unsigned int padto = 0, len = skb->len;
+
+ if (rtl_is_8125(tp) && len < 128 + RTL_MIN_PATCH_LEN &&
+ rtl_skb_is_udp(skb) && skb_transport_header_was_set(skb)) {
+ unsigned int trans_data_len = skb_tail_pointer(skb) -
+ skb_transport_header(skb);
+
+ if (trans_data_len >= offsetof(struct udphdr, len) &&
+ trans_data_len < RTL_MIN_PATCH_LEN) {
+ u16 dest = ntohs(udp_hdr(skb)->dest);
+
+ /* dest is a standard PTP port */
+ if (dest == 319 || dest == 320)
+ padto = len + RTL_MIN_PATCH_LEN - trans_data_len;
+ }
+
+ if (trans_data_len < sizeof(struct udphdr))
+ padto = max_t(unsigned int, padto,
+ len + sizeof(struct udphdr) - trans_data_len);
+ }
+
+ return padto;
+}
+
+static unsigned int rtl_quirk_packet_padto(struct rtl8169_private *tp,
+ struct sk_buff *skb)
+{
+ unsigned int padto;
+
+ padto = rtl8125_quirk_udp_padto(tp, skb);
+
switch (tp->mac_version) {
case RTL_GIGA_MAC_VER_34:
case RTL_GIGA_MAC_VER_60:
case RTL_GIGA_MAC_VER_61:
case RTL_GIGA_MAC_VER_63:
- return true;
+ padto = max_t(unsigned int, padto, ETH_ZLEN);
default:
- return false;
+ break;
}
+
+ return padto;
}

static void rtl8169_tso_csum_v1(struct sk_buff *skb, u32 *opts)
@@ -4164,9 +4219,10 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp,

opts[1] |= transport_offset << TCPHO_SHIFT;
} else {
- if (unlikely(skb->len < ETH_ZLEN && rtl_test_hw_pad_bug(tp)))
- /* eth_skb_pad would free the skb on error */
- return !__skb_put_padto(skb, ETH_ZLEN, false);
+ unsigned int padto = rtl_quirk_packet_padto(tp, skb);
+
+ /* skb_padto would free the skb on error */
+ return !__skb_put_padto(skb, padto, false);
}

return true;
@@ -4349,6 +4405,9 @@ static netdev_features_t rtl8169_features_check(struct sk_buff *skb,
if (skb->len < ETH_ZLEN)
features &= ~NETIF_F_CSUM_MASK;

+ if (rtl_quirk_packet_padto(tp, skb))
+ features &= ~NETIF_F_CSUM_MASK;
+
if (transport_offset > TCPHO_MAX &&
rtl_chip_supports_csum_v2(tp))
features &= ~NETIF_F_CSUM_MASK;
--
2.27.0