From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f46.google.com (mail-wm1-f46.google.com [209.85.128.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5C07D2FE585 for ; Mon, 1 Dec 2025 15:38:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764603511; cv=none; b=EULX9jkYeh+dfmgiEWUoI0rDkLOcR1sMPp7kHADCe1Fi6O4Wp12j2MnFCb6WoxEaynYg/5Y2kiE4917mY3qSx2FCcAXtbjhKBpJ+xwNmypUJM0gKMKdw1UbsWyR8Av2IyQ/k07oUfhP4IkHwzJvSuoTO2h24u2ivoqBcJAxY1Q8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764603511; c=relaxed/simple; bh=4bJza8pueDZleBXIQhQLXlVQYB/hddHey7ZJ+R9VXGo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ut4D++fJcudU4FLtrHjlOgTrBbEWLRKNdZsSEN5zB4dJmqT5k9W+YetRDf1//ezIYRQfHZkH7m8a16CcCEkUumXHfkd/E5USqO688loXwvqoyGskJxOXtPkQNo0gUOF1CYuaE/ECPWp80qYPFB6VwyYCDDKtQRQP79uBs2soNNg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=6wind.com; spf=pass smtp.mailfrom=6wind.com; dkim=pass (2048-bit key) header.d=6wind.com header.i=@6wind.com header.b=de9vEltu; arc=none smtp.client-ip=209.85.128.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=6wind.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=6wind.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=6wind.com header.i=@6wind.com header.b="de9vEltu" Received: by mail-wm1-f46.google.com with SMTP id 5b1f17b1804b1-4779ebfa91aso4663255e9.3 for ; Mon, 01 Dec 2025 07:38:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind.com; s=google; t=1764603507; x=1765208307; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:organization:content-language :from:references:cc:to:subject:reply-to:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=Z2Y5rI/vnOu9xFnlB5/iHpRXRGNHiOm/CVsZz1c745g=; b=de9vEltuU+02KsDSRA+AZPpT5FNfkZ8nDfaREhPX6VQ2zMuDQ+6nOdSyhQJ3+q83jN FtfcIv+7a/Z1ZbdA1+Xn6+E1NEyjOEelQi9dY/3nsoEeiMnYrdnMOsZPb8XEeuqP0VDl xkBv7d8dNk+aP1RfvMuL0ARz5dyQecQz+sb6T6aFodrfJbMF0B01Yc1YOSxfRtofNSAi iKBaBL7JZXZZTTd79d9zeC+qYlZQBhE0vg5vFuObGvbUuNX55eiGZWMFZj3LvexDG9gf xgHUPsLhA5gH07vwx4An9jBkCjyiEqypIBsazsykIkYZGDkRQzk6XJrFvBN/UTX+bbWN 3nYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764603507; x=1765208307; h=content-transfer-encoding:in-reply-to:organization:content-language :from:references:cc:to:subject:reply-to:user-agent:mime-version:date :message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Z2Y5rI/vnOu9xFnlB5/iHpRXRGNHiOm/CVsZz1c745g=; b=CBSk5PA5T3QDi6rEnD5SXIIn/c0X/K8NQfRV7EUx0YcpOMRe8sjJ0WOJF0megOE9rf E4y4zhN4aohNUWCGuyE/HCe9Mr910HxL4NBc6Ry7izhueCYH0UY2UIT1YUKX7HsvMXMr ++MXv2qj1fP94nwXi2hzFmWnJkelelqNo9iOaxpEhxICqLNlQyFR5pHkFMYiubc0gnSV Ogjgg4WNwspYseM8If8g0XRjtuWhM2CChsXC4/fWAI2mVJC1s1N5JCdYPkasPzfkZuk8 DkHto90r6MvnGZzT5jPMaoJT6ckKiqg6RQt+70RSHnKR82dgNRSfPZqkw50ZP52rh5TT JvOQ== X-Forwarded-Encrypted: i=1; AJvYcCXFGsMOWlbqGVpRTraaLs2cJ1jtLi51ONbJjKWmBbjVojtBoIX/F9E/nvJr/McaWDnUyarZoDnfR6OR4j4=@vger.kernel.org X-Gm-Message-State: AOJu0Ywj0WW9VfgYFguzqLKxBMJK2uvc7QrEtwgxTyF02x0lbrfZehvQ roGenzVktwn+PfLyR82oAchH8QaPEJyaOS4WZqISh0neNxuoF/gevNppgtNjnuBShXg= X-Gm-Gg: ASbGncv0nsMpVmdRquunEqwfxoB0SQ1f11OWS+a6Lxx1YxhU5IDAh94LksFR5G6YNz+ CXmUq3ZQc8Dd1aXa5cMIGmnHN7tYqgmipNUYVhqGRHWsUqWxH6QnhPyEJJF/J1f7u6dOjcxn13+ mNQfQss57Wz76hvasXm9DaxxHAqNeiHp2mHp5J8uJemRIM4JihY/1rSy6WZE3hg7uTdcMuah82F FTeIkVUp1Sh5tb4lOAcWtz7rrickw84EEOvBhx2cALbT8lCzuErnhnvSROtP2lgS08EXZNxk6py UUzzSykabRhiRIrNDkFPeNXoclIpCk027NKge8URlfmR11K0sBYStRuRVpqU8i7x1sCHNvS6Yar YKAgE0ShzupM9TTxsaBLtb/7PVY5lGfCZ7PNiYZJAjRc5va1+CETmG2fAm3Un2WNEvtdIqfk2Hu epHYfuMoziiJhmdpsm5HIY9ZzRjgMlTgH6fvoWpkRTsWCegltcWQHIyy2hrwWTzPoASgaQXP8qS g== X-Google-Smtp-Source: AGHT+IErJKv1q9m4cJJxeo+qG6to8LRvHNbExN+2Da3lRfFT78WtTFRvxTpTbbpp9JXzwwwbT6spdA== X-Received: by 2002:a05:600c:46c3:b0:477:aed0:f402 with SMTP id 5b1f17b1804b1-477c020242cmr207800645e9.8.1764603507531; Mon, 01 Dec 2025 07:38:27 -0800 (PST) Received: from ?IPV6:2a01:e0a:b41:c160:6a1d:efff:fe52:1959? ([2a01:e0a:b41:c160:6a1d:efff:fe52:1959]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4790addeeaasm307027235e9.7.2025.12.01.07.38.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 01 Dec 2025 07:38:26 -0800 (PST) Message-ID: Date: Mon, 1 Dec 2025 16:38:25 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH v2] net/ipv6: allow device-only routes via the multipath API To: azey Cc: Jakub Kicinski , David Ahern , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , netdev , linux-kernel References: <3k3facg5fiajqlpntjqf76cfc6vlijytmhblau2f2rdstiez2o@um2qmvus4a6b> <20251124190044.22959874@kernel.org> <19ac14b0748.af1e2f2513010.3648864297965639099@azey.net> <85a27a0d-de08-413d-af07-0eb3a3732602@6wind.com> <19ac5a2ee05.c5da832c80393.3479213523717146821@azey.net> <1d44e105-77bd-42e7-81f5-6e235fd12554@6wind.com> <19aca794ddd.105d1f97f173752.5540866508598154532@azey.net> <19acb23fcf6.126ff53f1199305.3435243475109739554@azey.net> <19acb2c1318.fb2ad2c5200221.6191734529593487240@azey.net> <56a0ec5c-da92-4f92-9697-71127866049b@6wind.com> <19acb95fbde.c1def42b209419.2689462649051838277@azey.net> From: Nicolas Dichtel Content-Language: en-US Organization: 6WIND In-Reply-To: <19acb95fbde.c1def42b209419.2689462649051838277@azey.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le 28/11/2025 à 18:49, azey a écrit : > On 2025-11-28 17:28:41 +0100 Nicolas Dichtel wrote: >> Le 28/11/2025 à 16:54, azey a écrit : >>>> On 2025-11-28 09:38:07 +0100 Nicolas Dichtel wrote: >>>>> With IPv6, unlike IPv4, the ECMP next hops can be added one by one. Your commit >>>>> doesn't allow this: >>> >>> Hold on, I think I understand what you actually meant by this, sorry. >>> I got too focused on regressions from the discussion in v1, I'll make >>> a v3 of the patch that allows dev-only routes to be added via append. >> Yes, that is what I pointed out. >> >> Please, add some self-tests to show that there is no regression. You probably >> have to test different combinations of NLM_F_* flags. See: >> >> https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/tree/ip/iproute.c#n2418 > > Will do, thanks for the pointer. > One last thing I'd like to clarify though: would this behavior not also > itself be considered a regression? > > Currently the add and append routes get added separately, and someone > could theoretically be relying on the kernel always picking the last > route instead of making them multipath - essentially still the same > v1 regression. That's a good question. I let others speak. But using the nexthop API would definitely close this question. I wonder why using this API is not possible for you. > > If not, would it also be acceptable for just any non-RTPROT_KERNEL > routes to automatically be made multipath like this? It's a simple fix, > it'd make appending work and it'd still prevent the specific v1 > regression for the case of two interfaces on the same subnet - example > diff attached. I don't think that the protocol field is reliable. The user can set it to whatever he wants.