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 11F22CA600A for ; Thu, 8 Oct 2026 09:05:09 +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:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=2KrY5bcaWM/iCHC3nc2lc6IZhhlnFZhRjcHEfSOffhc=; b=Q4Jq81aDc/ErNzWsCNNiw8nUIJ mAeHpWSgaj7CrscZITvcM4fGc4ioEsNtkrn0MfR98mw4Lhi8tERJzYSu9kZnLoBuae+cjKx9gZpGq KW0DArRThxcszu2PlOoRKL01IvGoqc9Osv+1/uAWRp22Y7lZWu+H77o/RYhE1prIQCCgb2rmyWaAZ KqN1OdDix2DO2LpaNg77NdVa3IXJADNxjqwtlLspo1m9Ck7NHMfDQyoeRyM+SDqwiy773jhsduROT XhEQr61wY1u80oBb0JlWegQQdgF5QAX+mrkR8CdCkanyo8456c4AZ1d6tYQkHj+neHIqVfXLhFa9S DOrYbNxw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEk3i-00000003xqo-2TnN; Thu, 08 Oct 2026 09:05:02 +0000 Received: from smtpout-02.galae.net ([185.246.84.56]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEk3f-00000003xnv-1jMT for linux-arm-kernel@lists.infradead.org; Thu, 08 Oct 2026 09:05:01 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 2752B1A1198; Thu, 8 Oct 2026 09:04:56 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id EB0F760341; Thu, 8 Oct 2026 09:04:55 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id DDD0810333858; Thu, 8 Oct 2026 11:04:45 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1791450294; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references; bh=2KrY5bcaWM/iCHC3nc2lc6IZhhlnFZhRjcHEfSOffhc=; b=e/czsAjf0rWzErVAmI2j6y8uq37jJSsLiC+dsdxFX5ON5yK894Fr5LVcPHY47YqppBGR6H 3qWeyYIZO+5xQTXNBGH0RM+8KKIObTrW/ygaWeafdTmnkunWv4CPau1Rv+0VInm+nWGVR2 bhS9+uH19X1f9rnCTqEfbAaE+4vEo8RTU7gOkWEwc9mxqt9JU+122iRny4aXhRxTwlDJt7 usPWQv5XeutXFW3nCt86T2mE1m3Rucnjg5eiSHn0UczmsXTJ2pyKEnaCMKL49hvFfZOSZQ InFMxm7YBFPSQ+C3XJ5dFvHVBPDg5YHptUUEaiYDNENh/E3oVAFOe6sZAra7Wg== Message-ID: Date: Thu, 8 Oct 2026 11:04:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v3 1/3] net: rss: Require indir table size or hash key size to support RSS To: Jakub Kicinski 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 References: <20261002142806.1299041-2-maxime.chevallier@bootlin.com> <179121059086.434549.5364767976780818051@kernel.org> <20261006163349.61c738e8@kernel.org> Content-Language: en-US From: Maxime Chevallier In-Reply-To: <20261006163349.61c738e8@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261008_020459_601827_9D57BB2E X-CRM114-Status: GOOD ( 11.26 ) 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 Hi Jakub, On 10/7/26 01:33, Jakub Kicinski wrote: > On Tue, 6 Oct 2026 09:59:29 +0200 Maxime Chevallier wrote: >>> [Severity: Medium] >>> rss_get_data_alloc() is shared by RSS_GET, RSS_SET and RSS_CREATE. Does >>> this drop flow-hash reporting for devices that have ->get_rxfh but report >>> 0/0 sizes? >> >> 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 ? Maxime