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 F09352836B5; Wed, 5 Nov 2025 18:39:51 +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=1762367993; cv=none; b=u2FvasBcr6ao1W5kpwxCaa2hszfDnTTkq8R0V1urVAMUKZ0p6wOY9zCpEfoixMk6DAjd2JbyYLMlyzYXSPOMelCtfI4YNvI9vzBob0oXxMRXVH+qZ35qgAiRzWE4f3+tfIY/V3FP8QbEnSDdxbeFkeNKg+3aXSlSsMT3+Wvh7pc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762367993; c=relaxed/simple; bh=7XDa5X5lmbUNgOnKU7PfOdgy4Ch0ycidqr0WWTqABIM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mSJbFXxdeEnDFa9yAqmm1YcasgtkJtm56oiTo8s4WBwG6WW7APOBsANWGJFmWg+4wn75W1jAuUqX8IpNSG3r9AbBNrHrt0G7xOshTeMMiVx9/1mF2yg3oZM1xJ3xVr4nnQs7mNPq4V04K9SZY79aG9obyKZv1W59we0m+xLdH+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AzaObCME; 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="AzaObCME" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FFFAC116B1; Wed, 5 Nov 2025 18:39:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762367991; bh=7XDa5X5lmbUNgOnKU7PfOdgy4Ch0ycidqr0WWTqABIM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=AzaObCMEOkPNWJblHA+XSNBv8eioXE7D8HzTI2sm196GLWUIiEcS91trLrbe8+TCw mmczy+qAGnYGNXI+E91lp6PYT05/h9ksu1TUPQ2WnXPXkukQBbar6P9/4pk3Hx8jcU sppIEtathxPvwGx0gbog6vaQYLXUvB/YTjXAR1ErNg8N1a66qdefkRZjUL268+4Wor i7xdIfCDfegfOAq4nbsR2zXmjnSmjp7uAJ7+9GKfMBfDv8oJiNkVySX/y7j6Q1DJ7W O56MmI771hr6UYprL0WYfRK++tM3cuVPl+P9FVqCgZkjp7UQLFtTaeHJma12GagMAH fF1XhXlwBjk3Q== Message-ID: <49edb9fa-56be-4853-aced-429f5b40b4be@kernel.org> Date: Wed, 5 Nov 2025 19:39:46 +0100 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 bpf 1/2] xdp: introduce xdp_convert_skb_to_buff() To: Maciej Fijalkowski , Jakub Kicinski Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, magnus.karlsson@intel.com, aleksander.lobakin@intel.com, ilias.apalodimas@linaro.org, toke@redhat.com, lorenzo@kernel.org, syzbot+ff145014d6b0ce64a173@syzkaller.appspotmail.com, Ihor Solodrai , Octavian Purdila References: <20251029221315.2694841-1-maciej.fijalkowski@intel.com> <20251029221315.2694841-2-maciej.fijalkowski@intel.com> <20251029165020.26b5dd90@kernel.org> <20251030082519.5db297f3@kernel.org> <20251030190511.62575480@kernel.org> <20251031114952.37d1cb1f@kernel.org> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 03/11/2025 13.16, Maciej Fijalkowski wrote: > On Fri, Oct 31, 2025 at 11:49:52AM -0700, Jakub Kicinski wrote: >> On Fri, 31 Oct 2025 12:37:37 +0100 Maciej Fijalkowski wrote: >>>>> would be fine for you? Plus AI reviewer has kicked me in the nuts on veth >>>>> patch so have to send v6 anyways. >>>> >>>> The veth side unfortunately needs more work than Mr Robot points out. >>>> For some reason veth tries to turn skb into an xdp_frame.. >>> >>> That is beyond the scope of the fix that I started doing as you're >>> undermining overall XDP support in veth, IMHO. >>> >>> I can follow up on this on some undefined future but right now I will >>> have to switch to some other work. >>> >>> If you disagree and insist on addressing skb->xdp_frame in veth within >>> this patchset then I'm sorry but I will have to postpone my activities >>> here. >> >> Yeah, I understand. A lot of the skb<>XDP integration is a steaming >> pile IMO, as mentioned elsewhere. I'd like to keep the core clean >> tho, so if there's some corner cases in veth after your changes >> I'll live. But I'm worried that the bugs in veth will make you >> want to preserve the conditional in xdp_convert_skb_to_buff() :( > > Probably the conditional would cover these corner cases, but I am not > insisting on it. skb_pp_cow_data() is called under certain circumstances > in veth but I have never seen a case on my side where it was skipped, > mostly because of headroom size being too small. This reminds me that we should change/increase veth net_device.needed_headroom when there is an XDP prog attached. As you said, today all SKB will basically get mem reallocated. --Jesper