From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D5134CC6B38 for ; Thu, 15 Oct 2026 23:37:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=sDbldnx1eZ//vxHr0/tLnnKthK+28bXbrhnsFJMTMq4=; b=ouFU9nCQwLpA1vqqIisMmHtusj HfHBK5+SCgtd8DHweLVa3VMIRyVMIP3c+OnsPJcREthe3clIfoiRnqo8IRSSMjyDG8xIbCHY8XG2F pD7AJ1g3oFcAX/l/WAPcGA6UmzXhzqNFat4kNKITVt74+bM5LXrYLmJVCmwxaAEkbDCZ47kQsojl/ VLImO5OG2KhiIrOeCpIvLclY6m6EOaYYt7CQ6rVuWLOGEgqAkU/zUfzpVuuBF4zRj1sI2kylCcs5G bQ15xdJz3o1yV1GQQDB7S6DsKmf5ILMokx6TbPXUAxyrhfzty3ut6r4l/8BW6jKlzd3MKZxj+Qzo5 gbZb1cww==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHV0K-00000001Z5G-0zvY; Thu, 15 Oct 2026 23:36:56 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHV0I-00000001Z59-2zNs for linux-arm-kernel@lists.infradead.org; Thu, 15 Oct 2026 23:36:54 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1E8394357D; Thu, 15 Oct 2026 23:36:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 572CE1F000C4; Thu, 15 Oct 2026 23:36:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792107414; bh=sDbldnx1eZ//vxHr0/tLnnKthK+28bXbrhnsFJMTMq4=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=LY1JkJOSLWADAUm2I/Ja+wKOJr1N8GWTCg2z8p4WsmRVff5Mcd+0aY4w3tasZQPIo AIhAJbC/qQKbF1SPIXnGZN7q3lFjt7vJ/sxbHym2n32/mjTZ0Jv8CQgrApMLbBsCli LDQ7RIgjtM4H7Q0630uBo1C2IcxF+5B5xKkx0PinrSJAJ+9n53N8r566qjsgmnapHe 39wFrB3HlZPJOx3+fHuKnbY5mSKy6SCyZl5n/hCgut5oxbcZPF+q+0YycoPdmdTFlt a486U9wor6hBV3XjRYN9p790SDDQEb4KrU89dl6KOZt7aHXUZ1hCv8UJOPJCaTnXgK zSOFCAEQ7stxA== Date: Thu, 15 Oct 2026 16:36:52 -0700 From: Jakub Kicinski To: Maxime Chevallier Cc: netdev-bot+sashiko@kernel.org, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, linux@armlinux.org.uk, lorenzo.bianconi@oss.qualcomm.com, nb@tipi-net.de, jitendra.vegiraju@broadcom.com, thomas.petazzoni@bootlin.com, alexis.lothore@bootlin.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, pbrobinson@gmail.com, joe@dama.to Subject: Re: [PATCH net-next v3 1/3] net: rss: Require indir table size or hash key size to support RSS Message-ID: <20261015163652.21ff3a98@kernel.org> In-Reply-To: References: <20261002142806.1299041-2-maxime.chevallier@bootlin.com> <179121059086.434549.5364767976780818051@kernel.org> <20261006163349.61c738e8@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 8 Oct 2026 11:04:44 +0200 Maxime Chevallier wrote: > >> Yes it does, that's the intended behaviour here. RSS bits are all optional, > >> but does it make sense to report hashing params when the indirection table > >> is size 0 and key len is 0 ? > > > > Not sure if there's an implementation in the tree but > > it's possible to implement poor man's RSS on strict > > power-of-2 queue set with some hashing built into the > > Rx engine, without a key. We'd still want to control > > which fields are hashed in this case. > > > > In the Netlink API we combine the two so we'd break this? > > Hmm I wasn't aware of that :( I guess the safe choice is to check on -EOPNOTSUPP > for .get_rxfh() + 0-len indir table / 0-size key and skip the device during the > dump instead of returning early ? Not sure I'm following the suggestion, isn't that what the v3 already does? I think the API was suggesting we let the device progress into the dump, and rely on the existing "unset" checks before the nla_put_ calls filter out the data which wasn't provided (which may be all the data). Not sure it's worth it, could you poke around to see if a device which reports zero-length key + indir table actually exists?