From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CAA63093A6 for ; Thu, 30 Apr 2026 16:21:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777566113; cv=none; b=Ec+kKfAmBHeIuicXtVeSGY2He9Z+8ybtrK10d/kTMdl3dJFWu15z4dq2MAzJ5+wH6jrinahd2zw9SJOxhfeLy13647AWy4PWtfdq8HzI3292wJ4RNm6DW0f+6fMEnwbGyR0FSgmWri8qf4hPqjGb+NNcaPfMa4Jx/S668DNay88= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777566113; c=relaxed/simple; bh=q1y7v3R/mJEb3oVMPBZ0EISfvAz0p1kLishWt8cqbrE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GDdB6eLIdxjDpbzqIU+0k8M/k1IpQpyWudAGv9h1z/YAzgIHBlhvdgp7KXV2xWDeqNyaBK6wEemn9w2leCa1nw0VBBrNLh0EHr9iP2oAmglVQa3ZEfkBgxTaHn5P8Y8jRyaMkETztVSvOmbRAOm2Wt/Fwe9OCv7XcbBePhaD/gA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eO0mTkYr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eO0mTkYr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9FEBC2BCB3; Thu, 30 Apr 2026 16:21:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777566113; bh=q1y7v3R/mJEb3oVMPBZ0EISfvAz0p1kLishWt8cqbrE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eO0mTkYr3Mhqw1AVngfjY5nvmPo4IBhVQer5hsPJ+v6G7+sd/JjGDlHl/jk4t3dVN 2pHT76YZVtfgEMR0YDt0ktbJCrzs72BsCt5+O9x19ZfdSncCQMpPv6XOTj5IYSH4oO sdmev+eekoP9aGFzO/PdXd3a4xziSKnTymtXKH/bqFThpxHj/j758EuZ2Xc511t/3j IqdEVU5XF+ItKFjpsZPMTAP8IwH2YZTdl6LmsODm+K7P+jBAKV1gb9tb5eLv5wOut3 G3PJZNO3tZZHbBzkntysBLFxyIBTkH5eNv+vkpHxQkyEzfN7CB5SdzblUxXrASUcjn rdbyUwEZ0J9FA== Date: Thu, 30 Apr 2026 17:21:49 +0100 From: Simon Horman To: michal.swiatkowski@linux.intel.com Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, jramaseu@redhat.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, aleksandr.loktionov@intel.com Subject: Re: [PATCH iwl-net v1 2/2] ice: use NETIF_F_HW_CSUM instead of IP/IPV6 Message-ID: <20260430162149.GC900403@horms.kernel.org> References: <20260428070647.777141-3-michal.swiatkowski@linux.intel.com> <20260430152948.1683359-2-horms@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260430152948.1683359-2-horms@kernel.org> On Thu, Apr 30, 2026 at 04:29:49PM +0100, Simon Horman wrote: > From: 'Simon Horman' > > This is an AI-generated review of your patch. The human sending this > email has considered the AI review valid, or at least plausible. > Full review at: https://sashiko.dev Sorry, the email I am responding to was supposed to come with some commentary - it seems my method for adding it is broken :( So I'm adding it below (as best as I can remember what it was). > --- > ice: use NETIF_F_HW_CSUM instead of IP/IPV6 > > This commit replaces the IP and IPV6 checksum offload flags with HW_CSUM > in the ice driver to allow hardware checksumming for IPv6 packets with > extension headers. It also removes the mutual exclusivity check between > TSO and GCS. > > > diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c > > index 5f92377d4dfc..33f252a6a22f 100644 > > --- a/drivers/net/ethernet/intel/ice/ice_main.c > > +++ b/drivers/net/ethernet/intel/ice/ice_main.c > > @@ -3491,9 +3491,8 @@ void ice_set_netdev_features(struct net_device *netdev) > > NETIF_F_RXHASH; > > > > csumo_features = NETIF_F_RXCSUM | > > - NETIF_F_IP_CSUM | > > NETIF_F_SCTP_CRC | > > - NETIF_F_IPV6_CSUM; > > + NETIF_F_HW_CSUM; > > By advertising NETIF_F_HW_CSUM, the network stack assumes the driver can handle > checksums for any protocol and passes non-IP packets (e.g., from AF_PACKET > injected frames) to the driver with CHECKSUM_PARTIAL. > > Since ice_tx_csum() strictly parses the L3 header and expects IPv4 or IPv6, > returning -1 for other protocols, will this regression cause non-IP packets to > be silently dropped instead of falling back to software checksums in the kernel? The problem above seems to be a legitimate concern, if a corner case. It seems to also exist in i40e. > Additionally, skb_csum_hwoffload_help() relies on NETIF_F_IPV6_CSUM to > safely fall back to software checksums when IPv6 extension headers are > present. > > Does using NETIF_F_HW_CSUM bypass this safeguard, potentially causing > legacy hardware (like E810) or E830 without GCS descriptors to compute > incorrect pseudo-headers and silently corrupt IPv6 packets with extension > headers? The issue above seems to be a false positive as the ice driver doesn't rely on the behaviour described. Rather ice_tx_csum() uses ipv6_skip_exthdr() to correctly handle extension headers. > > Finally, for protocols other than TCP, UDP, or SCTP, the driver falls back to > calling skb_checksum_help(skb) in the default case of ice_tx_csum(). > > However, the driver appears to ignore the return value of skb_checksum_help(). > > If skb_checksum_help() fails (e.g., due to -ENOMEM during pskb_expand_head()), > could this result in the packet being transmitted with an uncomputed checksum? The problem above seems real to me, but it also seems to be pre-existing. So I don't think it should delay progress of this patch. If it is a problem, it also seems to be present in i40e.