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([2a01:e0a:ab7:2110:6a1d:efff:fe52:1959]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49c607d12c4sm84484f8f.41.2026.11.12.08.26.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2026 08:26:53 -0800 (PST) Message-ID: Date: Thu, 12 Nov 2026 17:26:53 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH net-next] ipv6: always apply all.force_forwarding to every interface To: Gabriel Goller , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , Randy Dunlap , David Ahern , Ido Schimmel Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20261112-ipv6_always_apply-v1-1-8df846631005@proxmox.com> From: Nicolas Dichtel Content-Language: en-US Organization: 6WIND In-Reply-To: <20261112-ipv6_always_apply-v1-1-8df846631005@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le 12/11/2026 à 14:41, Gabriel Goller a écrit : > Currently, writing to all.force_forwarding updates the interfaces > only if the value stored in all.force_forwarding changes. Setting an > interface to a different value and then writing the same value to all > leaves that interface unchanged: > > # sysctl -wq net.ipv6.conf.all.force_forwarding=1 > # sysctl -wq net.ipv6.conf.dummy1.force_forwarding=0 > # sysctl -wq net.ipv6.conf.all.force_forwarding=1 > # sysctl net.ipv6.conf.dummy1.force_forwarding > net.ipv6.conf.dummy1.force_forwarding = 0 > > Apply every write to all.force_forwarding to all interfaces, even when > its stored value is unchanged, matching all.forwarding. In the example, > the final write to all now sets dummy1.force_forwarding back to 1. > > Also match forwarding's locking: take RTNL for every write and compare > the old and new values under the lock, rather than returning early based > on an unlocked comparison. Send netconf notifications only for actual > value changes, including for default and per-interface writes. > > Note that IPv4's forwarding does not behave like this, but we won't > change that one and align force_forward to the IPv6 forwarding. > > Fixes: f24987ef6959 ("ipv6: add `force_forwarding` sysctl to enable per-interface forwarding") > Suggested-by: Nicolas Dichtel > Signed-off-by: Gabriel Goller Reviewed-by: Nicolas Dichtel