From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:44072) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEehA-0002zc-EW for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hEeh9-0005Hc-Go for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:08 -0400 Received: from hera.aquilenet.fr ([185.233.100.1]:54862) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hEeh9-0005CB-7W for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:07 -0400 Date: Thu, 11 Apr 2019 20:45:02 +0200 From: Samuel Thibault Message-ID: <20190411184502.xvesnriqcocyvuan@function> References: <20190405184648.17029-1-dgilbert@redhat.com> <20190405212501.cdg4u3m7ihldcop4@function> <20190408084653.GB2687@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190408084653.GB2687@work-vm> Subject: Re: [Qemu-devel] [PATCH] slirp: Gcc 9 -O3 fix List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, jan.kiszka@siemens.com Hello, Dr. David Alan Gilbert, le lun. 08 avril 2019 09:46:53 +0100, a ecrit: > 'soread' has the comment: > > /* > * No need to check if there's enough room to read. > * soread wouldn't have been called if there weren't > */ > sopreprbuf(so, iov, &n); > > the compiler doesn't realise that, and is moaning about the case > where the if (len <=0) return happens and the following > code tries to use iov. I see. Perhaps we should make this an assert then? In case this isn't true, i.e. soread() is called even if no room is available, returning 0 would probably just let the caller just try again, and we should rather just plainly crash than hang? Samuel 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 X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 415C6C10F13 for ; Thu, 11 Apr 2019 18:46:22 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 11EB42083E for ; Thu, 11 Apr 2019 18:46:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 11EB42083E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:53433 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEeiL-0003sS-6U for qemu-devel@archiver.kernel.org; Thu, 11 Apr 2019 14:46:21 -0400 Received: from eggs.gnu.org ([209.51.188.92]:44072) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEehA-0002zc-EW for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hEeh9-0005Hc-Go for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:08 -0400 Received: from hera.aquilenet.fr ([185.233.100.1]:54862) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hEeh9-0005CB-7W for qemu-devel@nongnu.org; Thu, 11 Apr 2019 14:45:07 -0400 Received: from localhost (localhost [127.0.0.1]) by hera.aquilenet.fr (Postfix) with ESMTP id 2FAD0A868; Thu, 11 Apr 2019 20:45:04 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at aquilenet.fr Received: from hera.aquilenet.fr ([127.0.0.1]) by localhost (hera.aquilenet.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1FU5m5O0EFeP; Thu, 11 Apr 2019 20:45:03 +0200 (CEST) Received: from function (105.251.129.77.rev.sfr.net [77.129.251.105]) by hera.aquilenet.fr (Postfix) with ESMTPSA id 91A9EA864; Thu, 11 Apr 2019 20:45:03 +0200 (CEST) Received: from samy by function with local (Exim 4.92) (envelope-from ) id 1hEeh4-0007UO-TA; Thu, 11 Apr 2019 20:45:02 +0200 Date: Thu, 11 Apr 2019 20:45:02 +0200 From: Samuel Thibault To: "Dr. David Alan Gilbert" Message-ID: <20190411184502.xvesnriqcocyvuan@function> References: <20190405184648.17029-1-dgilbert@redhat.com> <20190405212501.cdg4u3m7ihldcop4@function> <20190408084653.GB2687@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190408084653.GB2687@work-vm> Organization: I am not organized User-Agent: NeoMutt/20170113 (1.7.2) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 185.233.100.1 Subject: Re: [Qemu-devel] [PATCH] slirp: Gcc 9 -O3 fix X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jan.kiszka@siemens.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190411184502.YA40qla51cZ5T67N4APaevfoAUsTgBpuzjL760yFlrY@z> Hello, Dr. David Alan Gilbert, le lun. 08 avril 2019 09:46:53 +0100, a ecrit: > 'soread' has the comment: > > /* > * No need to check if there's enough room to read. > * soread wouldn't have been called if there weren't > */ > sopreprbuf(so, iov, &n); > > the compiler doesn't realise that, and is moaning about the case > where the if (len <=0) return happens and the following > code tries to use iov. I see. Perhaps we should make this an assert then? In case this isn't true, i.e. soread() is called even if no room is available, returning 0 would probably just let the caller just try again, and we should rather just plainly crash than hang? Samuel