Re: [PATCH v4 net] r8169: work around RTL8125 UDP hw bug

On Thu, Jan 28, 2021 at 5:02 PM Heiner Kallweit [off-list ref] wrote:

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 <redacted>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

Acked-by: Willem de Bruijn <willemb@google.com>

Thanks for the quick iterations. I was afraid that the switch with
implicit fall-through to the default label could trigger
Wimplicit-fallthrough, but it seems that warning is suppressed if the
case only has a break or return. It's not strictly needed in that
case, but no need to respin just for that, either.