From: Jakub Kicinski <kuba@kernel.org>
To: Xin Xie <xiexinet@gmail.com>
Cc: netdev@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org, davem@davemloft.net,
edumazet@google.com, pabeni@redhat.com, horms@kernel.org,
andrew+netdev@lunn.ch, shuah@kernel.org, kees@kernel.org,
petr.wozniak@gmail.com, qingfang.deng@linux.dev,
fmaurer@redhat.com, luka.gejak@linux.dev, bigeasy@linutronix.de,
xiaoliang.yang_1@nxp.com, skhawaja@google.com,
liuhangbin@gmail.com, stable@vger.kernel.org,
sdf.kernel@gmail.com
Subject: Re: [PATCH 1/4] net: hsr: fix packet drops caused by GRO superpackets
Date: Thu, 13 Aug 2026 18:21:11 -0700 [thread overview]
Message-ID: <20260813182111.088aee3d@kernel.org> (raw)
In-Reply-To: <20260809121455.1745-2-xiexinet@gmail.com>
On Sun, 9 Aug 2026 14:14:51 +0200 Xin Xie wrote:
> HSR/PRP process each wire frame separately for tagging and duplicate
> discard. GRO on a lower device hides multiple frames in one skb, which
> cannot be forwarded with valid per-frame metadata.
>
> Disable GRO and GRO_HW when a lower device is enslaved, matching the
> existing LRO handling.
>
> This is best effort because GRO may be re-enabled and some devices cannot
> disable GRO_HW. The forward-entry segmentation fix handles plain,
> trailer-free GSO skbs that still arrive; device-specific fixed-on GRO_HW
> output is outside this guarantee.
1) could you explain in more detail why GRO is breaking things?
GRO shouldn't merge packets with different L2/L2.5 and packets
with trailers?
2) the code seems inspired by LRO but LRO also has
NETIF_F_UPPER_DISABLES. This change looks rather incomplete.
Calling it "best effort" seems like an excuse.
3) Clashiko has a number of other comments:
https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260809121455.1745-1-xiexinet@gmail.com
--
pw-bot: cr
next prev parent reply other threads:[~2026-08-14 1:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-09 12:14 [PATCH net v6 0/4] net: hsr: fix GRO/GSO super-packet handling Xin Xie
2026-08-09 12:14 ` [PATCH 1/4] net: hsr: fix packet drops caused by GRO superpackets Xin Xie
2026-08-14 1:21 ` Jakub Kicinski [this message]
2026-08-09 12:14 ` [PATCH 2/4] net: hsr: shrink seqnr_lock to sequence counter updates Xin Xie
2026-08-10 2:23 ` Hangbin Liu
2026-08-09 12:14 ` [PATCH 3/4] net: hsr: unfold GSO super-packets at the forward entry Xin Xie
2026-08-09 12:14 ` [PATCH 4/4] selftests: net: hsr: cover GSO super-packets on PRP slave ingress Xin Xie
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