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 309632D060B; Sat, 28 Feb 2026 03:04:42 +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=1772247883; cv=none; b=Z98loKKbQdT+Uy/1MFsYW7v9KKNBQCkPLJY3FoU603CqW0YClq/w637+OZdQEdFtbA3pQKEEsCyu/c3pPWb7KOjkHKnp0kP/p9jPzau/Yhonmponkf/rLQLpSnNNzLNFWf7VDY6xVUxq+8a8GZQ8lMfuTogdjsr+xtWxGimbfxc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772247883; c=relaxed/simple; bh=rRuJLJjVEC/iekwBQX86ikOn2y19JbbiL+COLF9Ggko=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Z2TWaIRj9oOcJnUtUofJbk/0h3JtnxtAwUgQLj0xmvXowzgP9pgoxq19lTwlO4T4yW22L4/6Ld4h0zYG9EZo/FI8PGyPInAuIAA2d/Ha9dE30KoTYU6ttpkYoKJSrL40ynvUPayeDREg3W2eVbiKJQDS8WDscGVjGnGUO/yNoRc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cqe468Ay; 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="Cqe468Ay" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BE5DC116C6; Sat, 28 Feb 2026 03:04:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772247882; bh=rRuJLJjVEC/iekwBQX86ikOn2y19JbbiL+COLF9Ggko=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Cqe468AycrTejrSZ2zNpH7qZhqpTDEPWcdW/VXH4QsHaR6O5llBbUEK3hhkiTjPuf vHrDzBvjixnK3w/yGGzxbhnPyIQnIK3OfMFtfzwzsJziSz9LESj+s1mhV3QHjWWvFE elrnxA03RpR7vioK5Jt1B7pnfPkDtfuwRWBJo7DF0KA0r8dHMIEAJg5/n1xF+Me9Q5 STIcIpwX7BuLdzI8PeSB50idfUMkwbnO9J6aCy0dYVWgdty0imGhRv5fGuYET419qq DxkPWsyMP3hoYHWdpPTTgIhxdpIb0puetuRJNv5O55qiR/H1aAdPvQPyOdchlz1Tbc 8yctGVfXjv5hg== Date: Fri, 27 Feb 2026 19:04:41 -0800 From: Jakub Kicinski To: Kibaek Yoo Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: macvlan: fix multicast delivery to bridge ports with shared source MAC Message-ID: <20260227190441.0bb7b01d@kernel.org> In-Reply-To: <20260225100024.38937-1-psykibaek@gmail.com> References: <20260225100024.38937-1-psykibaek@gmail.com> 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-Transfer-Encoding: 7bit On Wed, 25 Feb 2026 19:00:24 +0900 Kibaek Yoo wrote: > When a macvlan interface in bridge mode shares its MAC address with an > external source (e.g., VRRP virtual MAC), incoming multicast frames > from that external source are incorrectly identified as locally > originated. macvlan_hash_lookup() matches the source MAC to a local > macvlan, causing macvlan_multicast_rx() to skip delivery to bridge > ports under the assumption they already received the frame during > transmission. > > This assumption fails for protocols like VRRP where multiple hosts > legitimately share the same virtual MAC address. The local macvlan > never transmitted the frame, so bridge ports never saw it, yet the > multicast is not delivered to them. > > Fix this by passing NULL as the source device and including > MACVLAN_MODE_BRIDGE in the mode mask for the else branch of The change looks fine, AFAICT. But please rephrase the commit message to avoid making it sound like a fix. The VRRP use case is rather odd and it was simply not supported earlier. Now you're adding support with the tradeoff you note below. We don't want AI-based backporting bots to pull this into LTS. Please try to add a test case for your use case in selftests. > macvlan_multicast_rx(). This ensures all VEPA and bridge mode macvlan > interfaces receive incoming multicast regardless of source MAC > matching. The trade-off is that looped-back locally-originated > multicasts may be delivered to bridge ports a second time, but > multicast consumers already handle duplicate frames. -- pw-bot: cr