From: Simon Horman <horms@kernel.org>
To: Matt Fleming <matt@readmodwrite.com>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@cloudflare.com,
Matt Fleming <mfleming@cloudflare.com>
Subject: Re: [Intel-wired-lan] [PATCH net] ice: Fix missing 1's complement negation in GCS raw checksum
Date: Mon, 13 Apr 2026 15:11:26 +0100 [thread overview]
Message-ID: <20260413141126.GR469338@kernel.org> (raw)
In-Reply-To: <20260408190214.1287708-1-matt@readmodwrite.com>
On Wed, Apr 08, 2026 at 08:02:14PM +0100, Matt Fleming wrote:
> From: Matt Fleming <mfleming@cloudflare.com>
>
> Commit 905d1a220e8d ("ice: Add E830 checksum offload support") added
> Generic Checksum (GCS) support for E830 NICs but omitted the 1's
> complement negation (~) when converting the hardware raw_csum to
> skb->csum for CHECKSUM_COMPLETE.
>
> Without the negation, every CHECKSUM_COMPLETE packet fails the
> fast-path validation in nf_ip_checksum() and falls through to software
> checksumming via __skb_checksum_complete(), which triggers the
> rate-limited "hw csum failure" warning. Packets are still accepted
> (the software recheck passes) but hardware checksum offload is
> effectively disabled and the warning floods dmesg on systems running
> nf_conntrack on VLAN sub-interfaces.
>
> Multiple other drivers (idpf, ehea, iwlwifi, cassini, sunhme, enetc)
> also apply ~ for CHECKSUM_COMPLETE. The ice driver was the only in-tree
> user of csum_unfold() for CHECKSUM_COMPLETE that omitted it.
>
> Fixes: 905d1a220e8d ("ice: Add E830 checksum offload support")
> Signed-off-by: Matt Fleming <mfleming@cloudflare.com>
Reviewed-by: Simon Horman <horms@kernel.org>
WARNING: multiple messages have this Message-ID (diff)
From: Simon Horman <horms@kernel.org>
To: Matt Fleming <matt@readmodwrite.com>
Cc: Tony Nguyen <anthony.l.nguyen@intel.com>,
Przemek Kitszel <przemyslaw.kitszel@intel.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@cloudflare.com,
Matt Fleming <mfleming@cloudflare.com>
Subject: Re: [PATCH net] ice: Fix missing 1's complement negation in GCS raw checksum
Date: Mon, 13 Apr 2026 15:11:26 +0100 [thread overview]
Message-ID: <20260413141126.GR469338@kernel.org> (raw)
In-Reply-To: <20260408190214.1287708-1-matt@readmodwrite.com>
On Wed, Apr 08, 2026 at 08:02:14PM +0100, Matt Fleming wrote:
> From: Matt Fleming <mfleming@cloudflare.com>
>
> Commit 905d1a220e8d ("ice: Add E830 checksum offload support") added
> Generic Checksum (GCS) support for E830 NICs but omitted the 1's
> complement negation (~) when converting the hardware raw_csum to
> skb->csum for CHECKSUM_COMPLETE.
>
> Without the negation, every CHECKSUM_COMPLETE packet fails the
> fast-path validation in nf_ip_checksum() and falls through to software
> checksumming via __skb_checksum_complete(), which triggers the
> rate-limited "hw csum failure" warning. Packets are still accepted
> (the software recheck passes) but hardware checksum offload is
> effectively disabled and the warning floods dmesg on systems running
> nf_conntrack on VLAN sub-interfaces.
>
> Multiple other drivers (idpf, ehea, iwlwifi, cassini, sunhme, enetc)
> also apply ~ for CHECKSUM_COMPLETE. The ice driver was the only in-tree
> user of csum_unfold() for CHECKSUM_COMPLETE that omitted it.
>
> Fixes: 905d1a220e8d ("ice: Add E830 checksum offload support")
> Signed-off-by: Matt Fleming <mfleming@cloudflare.com>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-04-13 14:11 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-08 19:02 [Intel-wired-lan] [PATCH net] ice: Fix missing 1's complement negation in GCS raw checksum Matt Fleming
2026-04-08 19:02 ` Matt Fleming
2026-04-09 8:45 ` [Intel-wired-lan] " Loktionov, Aleksandr
2026-04-09 8:45 ` Loktionov, Aleksandr
2026-04-13 14:11 ` Simon Horman [this message]
2026-04-13 14:11 ` Simon Horman
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