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04 May 2026 01:13:53 -0700 X-CSE-ConnectionGUID: FJTjzmBeRjKWGxOzEDSmhA== X-CSE-MsgGUID: UPX6moqJSWqissfla8fyxg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,215,1770624000"; d="scan'208";a="230852817" Received: from mev-dev.igk.intel.com ([10.237.112.144]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 May 2026 01:13:51 -0700 Date: Mon, 4 May 2026 10:09:55 +0200 From: Michal Swiatkowski To: Simon Horman Cc: michal.swiatkowski@linux.intel.com, 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 Message-ID: References: <20260428070647.777141-3-michal.swiatkowski@linux.intel.com> <20260430152948.1683359-2-horms@kernel.org> <20260430162149.GC900403@horms.kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260430162149.GC900403@horms.kernel.org> X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1777882434; x=1809418434; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=i0ow0BGME4ktvZKUNMDO7lIwbJDhWGcBGUZClqgLTvE=; b=C0Os4fDiK/tiJxWEygkm/r4sTvACATvvtm8Ebf4pL9vlN4At9W9/7TZb SL1YgRXP644wpbcdrvtsiIIBbFijc+n0h8VFX2eEnpOgWuuTWmV2o2AC9 B6ASbWfNINq1g4H3Pq3qmpqJL4/sO0Qq5EwMkoXf2/6fhCnFqH3miLGeM TRS1OmB4X0YUFSD3BBgZ2jIlZDrdQY7KCPsCLohxOsX+6qgWnpfkWD90b BxMhb8teU5ZEv5BWxoRULUB7qHRpD/ddVa8J+g3VoE9TsQJU4Wc9/xo1Q /QkHwvwoXeG+ZVDlxMDRWkQ+c6csKi5cLpOg3mhQpcTznfX7O8ussmfv2 w==; X-Mailman-Original-Authentication-Results: smtp4.osuosl.org; dmarc=none (p=none dis=none) header.from=linux.intel.com X-Mailman-Original-Authentication-Results: smtp4.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=C0Os4fDi Subject: Re: [Intel-wired-lan] [PATCH iwl-net v1 2/2] ice: use NETIF_F_HW_CSUM instead of IP/IPV6 X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On Thu, Apr 30, 2026 at 05:21:49PM +0100, Simon Horman wrote: > 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). > Thanks for adding the comments. > > --- > > 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. > I think there is a lack of skb_checksum_help() before one error return from ice_tx_csum(). I will add it. > > 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. > Yeah, righ. > > > > 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. idpf, igbe too. It should return error in such case and drop the packet. What do you think, should I add the patch for that here or send it separately? To be honest I prefer sending it separately as this is in already exsisting code and touch more than one driver. Thanks