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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69021EB64DA for ; Fri, 30 Jun 2023 16:14:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D69318E0034; Fri, 30 Jun 2023 12:14:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D1B3C8E000F; Fri, 30 Jun 2023 12:14:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BE0AA8E0034; Fri, 30 Jun 2023 12:14:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AC12A8E000F for ; Fri, 30 Jun 2023 12:14:46 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 7F9861A048A for ; Fri, 30 Jun 2023 16:14:46 +0000 (UTC) X-FDA: 80959912572.22.E88BA1F Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf02.hostedemail.com (Postfix) with ESMTP id BE09980029 for ; Fri, 30 Jun 2023 16:14:44 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WAwX+Yr1; spf=pass (imf02.hostedemail.com: domain of kuba@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=kuba@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1688141684; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kB33pndS5vV/ESSwLE8QYADv8BYywynVrNEBLXlX9Ng=; b=0AbRKNgCNYcXkDmMBmZnLrkPQH64gHNCSfXQGbdq95PJnryFTRjS146CouJXr+QS6pTrKG BVXUsxZ40R2UNr6cm9RpDId3S4blgTn47HExSnOn+DvKz/E7rKeKFbDn5241o8fXAa0XoA 0SRo8nimPBCrdgueESsabMYk8CUZmuc= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1688141684; a=rsa-sha256; cv=none; b=dDXuYNWcWEIF3G5jff5XzeiqJwKZVu8ro5gW5lY2GA2kzJyZQcHiSewIe3IzTvT1iXJfZE J5P65qOtuzFsw+tSAyyxwYtI8ijI7QB9YYCrtapPg730mWgmQZ6ErWcuSzXhr12XCuu1BX j4bKMrVygpo8qHdGyyaNnuTqWouUzsg= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WAwX+Yr1; spf=pass (imf02.hostedemail.com: domain of kuba@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=kuba@kernel.org; dmarc=pass (policy=none) header.from=kernel.org Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 069346178A; Fri, 30 Jun 2023 16:14:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C914CC433C8; Fri, 30 Jun 2023 16:14:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688141683; bh=OQ6W9Mf8SjuyriHv2gHrYTgggbQw7sK3MPN4gMZ87ZI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WAwX+Yr1sAkgsIUXUcFV1FByBoFxm26kJ7kIXPDZuGZE6iqLBI4Ji4g8eHF9X4TSf FZtftQgV87fi5h6nmkFhmUYeD4+za+zR5E2WkJqQVxhUmIEQOKUjm75ZQitaGSzk4J 0OrJqdu7MlktJKEdYMUYINhOzGyzvwS7S17WgDP1iUbaNYmxxfgBXY3DEyz+shCASI ziTLDz9Y8rHUXBphJJXTXNIwHHHo4meZmPD/qhmizwVEX8m9VH+O/8vzoVL1+RILxf yyLfKRBJM1M/Kl0fMmQn+t8c8s4Z/nZAuv8TJUfSnr1vtWj9rA1ccEucxd/97CeE9d XUagxkK+qJVIQ== Date: Fri, 30 Jun 2023 09:14:42 -0700 From: Jakub Kicinski To: Nathan Chancellor Cc: David Howells , Aurelien Aptel , netdev@vger.kernel.org, Alexander Duyck , "David S. Miller" , Eric Dumazet , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sagi Grimberg , Willem de Bruijn , Keith Busch , Jens Axboe , Christoph Hellwig , Chaitanya Kulkarni , linux-nvme@lists.infradead.org, llvm@lists.linux.dev Subject: Re: [PATCH net-next v3 10/18] nvme/host: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage Message-ID: <20230630091442.172ec67f@kernel.org> In-Reply-To: <20230630161043.GA2902645@dev-arch.thelio-3990X> References: <253mt0il43o.fsf@mtr-vdi-124.i-did-not-set--mail-host-address--so-tickle-me> <20230620145338.1300897-1-dhowells@redhat.com> <20230620145338.1300897-11-dhowells@redhat.com> <58466.1688074499@warthog.procyon.org.uk> <20230629164318.44f45caf@kernel.org> <20230630161043.GA2902645@dev-arch.thelio-3990X> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: BE09980029 X-Rspam-User: X-Stat-Signature: 84c131xeido5oas73gwaucce58penue4 X-Rspamd-Server: rspam03 X-HE-Tag: 1688141684-82501 X-HE-Meta: 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 fsyYCKCE 8/JcsDCr7RwzVjFzkNqISlC0tR1ilfPwApuAbkcZhE3UBlFxAbPFkdNn08XV8zBn78tVzgYPFH7+loRjClF2iqM1u7L5Qxn4p3DTrsZN2l8ZbES2f9Mozhz33t5OJdnfx3/PFQ75t2ONLxEqUNlFiSZzsPD8t1W9KgtsUB1CBrqoz7Nu32PXi2F7tlDGazAzmZah/yfcHrfAfOn4wKlYRSPdM5gdME0O8nOnfmdNkltm+7WtxfPBf/7CH+FMDQKsXXd5nwKU1K+Cg/aOTicYrbfgdecD9ak14k8Mwk6esv4OtXOV6T+JH34cjoZT2C8qo1ox9UlYcUfMqOfLUGZIITj6vlcJhCIDsjyIel7Hv3VRedl5l0BaZvdCxwvfOqF7uZAUuyYXXuygRT9j2JAWVbdlSykUd+QhPhQ1UhBlg6OPRIASEd72ls5LcAEVdY9OE8Q7VaCsZxHZc1CHkE+mJjLzvsg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 30 Jun 2023 09:10:43 -0700 Nathan Chancellor wrote: > > Let me CC llvm@ in case someone's there is willing to make > > the compiler warn about this. > > Turns out clang already has a warning for this, -Wcomma: > > drivers/nvme/host/tcp.c:1017:38: error: possible misuse of comma operator here [-Werror,-Wcomma] > 1017 | msg.msg_flags &= ~MSG_SPLICE_PAGES, > | ^ > drivers/nvme/host/tcp.c:1017:4: note: cast expression to void to silence warning > 1017 | msg.msg_flags &= ~MSG_SPLICE_PAGES, > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > | (void)( ) > 1 error generated. > > Let me do some wider build testing to see if it is viable to turn this > on for the whole kernel because it seems worth it, at least in this > case. There are a lot of cases where a warning won't be emitted (see the > original upstream review for a list: https://reviews.llvm.org/D3976) but > something is better than nothing, right? :) Ah, neat. Misleading indentation is another possible angle, I reckon, but not sure if that's enabled/possible to enable for the entire kernel either :( We test-build with W=1 in networking, FWIW, so W=1 would be enough for us.