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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD151EB64D7 for ; Fri, 30 Jun 2023 16:15:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232646AbjF3QPD (ORCPT ); Fri, 30 Jun 2023 12:15:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232943AbjF3QOp (ORCPT ); Fri, 30 Jun 2023 12:14:45 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 947AA3C06 for ; Fri, 30 Jun 2023 09:14:44 -0700 (PDT) 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 1DCCA61795 for ; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.