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=-14.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 B3E79C433B4 for ; Fri, 23 Apr 2021 14:13:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6AB80613C9 for ; Fri, 23 Apr 2021 14:13:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239051AbhDWOOH (ORCPT ); Fri, 23 Apr 2021 10:14:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231362AbhDWOOE (ORCPT ); Fri, 23 Apr 2021 10:14:04 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A2DAC061574; Fri, 23 Apr 2021 07:13:27 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id y204so24724629wmg.2; Fri, 23 Apr 2021 07:13:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=+xcvu/qUqC379ECYMecXBCghxgPo0LkCVkt2Sha9gI0=; b=gQgwCnTzceuYX9YXXn/QOmHMV11y2gRdZn+SaqQAqce3IYcX2Wu6DPsa2XTyXMwA8c Vcs5xo5CfyzTiBEG8jBLci4gkAg46lPW9wOna7DHauPVw3xZ76hVSl8aOT2RQITKOgag SJ3JbPnHe9P+PWd+SODYhml/XsWppDUqCEI64TzAToDrmy9IB1D5Oi9nQanNpAzb6LLu 9vOF32avT/iwL3ShCQdjSqnrC5tBgNGMHi9dhlHorSlIX4yLXMvjGkb+JbIZW/I0L9UD n0nou87Fi8LkD1W1jeng96D6VgE+9vAvuhe2nYqHoqTQBnPWkBDqqBhFRZdjVr5jCwKj 2wbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=+xcvu/qUqC379ECYMecXBCghxgPo0LkCVkt2Sha9gI0=; b=Avu4Hly2pnTL4//HJpe/jOoxGDmBauAJvgyvy/x3mLkeoo6WLvpuz1MU30+BmuHkE/ zV9yADX5exXcrseMjZ+cCliub3Eva02iMv0IkzvDi34AaZIiqim1qN3rEugZ+BIqa8md +JWmnfKWV+vVvRGn2LdRlImS0CEM9acy+IlCrGWicA6cVVe11RWcy7lKWLvTjQWtjAcn qZAIWay9k4ieLh08Gahe0CawPsijtG2XoxkVJ7CtK7Xoq5xTXpkMnJhfphFagAFjh/Hg Rs1VjZtCD17yRZcCwPzvSE+dYaCDhLjNlEIxhh4acCOYqTwdPEskMNtPHZcN4vKLlsZK T2VA== X-Gm-Message-State: AOAM5325oqdvhBYv/jB72PxfZ6vA2uhq1yMdzYAC7oGRJ6ffG6U/3E/b SKTgq80CdpNtS+lwBgXbN3rapsYu7iY6LA== X-Google-Smtp-Source: ABdhPJwGYKqIZGrnrk6Gs4g9YAaDa7qDHh64cpdd7i8Xm82tWJs9djKmU8ZbylX1l5Vqc6GiYhAgWg== X-Received: by 2002:a05:600c:6d4:: with SMTP id b20mr5806496wmn.99.1619187206018; Fri, 23 Apr 2021 07:13:26 -0700 (PDT) Received: from [192.168.8.197] ([148.252.128.225]) by smtp.gmail.com with ESMTPSA id j12sm9135705wro.29.2021.04.23.07.13.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 23 Apr 2021 07:13:25 -0700 (PDT) Subject: Re: [PATCH liburing] examples/ucontext-cp.c: cope with variable SIGSTKSZ To: Stefano Garzarella , Stefan Hajnoczi Cc: io-uring@vger.kernel.org, "H.J. Lu" , libc-alpha@sourceware.org, Jens Axboe , linux-block@vger.kernel.org References: <20210413150319.764600-1-stefanha@redhat.com> <20210422142245.evlxjvfw3emh7ivw@steredhat> From: Pavel Begunkov Message-ID: <89aaba8e-9a39-5269-201f-83d1f96e1ec0@gmail.com> Date: Fri, 23 Apr 2021 15:13:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: <20210422142245.evlxjvfw3emh7ivw@steredhat> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 4/22/21 3:22 PM, Stefano Garzarella wrote: > +Cc: io-uring@vger.kernel.org > +Cc: Pavel Begunkov > > Original message: https://www.spinics.net/lists/linux-block/msg67077.html > > On Thu, Apr 22, 2021 at 10:59:42AM +0100, Stefan Hajnoczi wrote: >> On Mon, Apr 19, 2021 at 11:38:07AM -0700, H.J. Lu wrote: >>> On Mon, Apr 19, 2021 at 7:35 AM Stefan Hajnoczi wrote: >>> > >>> > On Tue, Apr 13, 2021 at 04:03:19PM +0100, Stefan Hajnoczi wrote: >>> > > The size of C arrays at file scope must be constant. The following >>> > > compiler error occurs with recent upstream glibc (2.33.9000): >>> > > >>> > >   CC ucontext-cp >>> > >   ucontext-cp.c:31:23: error: variably modified ‘stack_buf’ at file scope >>> > >   31 |         unsigned char stack_buf[SIGSTKSZ]; >>> > >      |                       ^~~~~~~~~ >>> > >   make[1]: *** [Makefile:26: ucontext-cp] Error 1 >>> > > >>> > > The following glibc commit changed SIGSTKSZ from a constant value to a >>> > > variable: >>> > > >>> > >   commit 6c57d320484988e87e446e2e60ce42816bf51d53 >>> > >   Author: H.J. Lu >>> > >   Date:   Mon Feb 1 11:00:38 2021 -0800 >>> > > >>> > >     sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] >>> > >   ... >>> > >   +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ) >>> > > >>> > > Allocate the stack buffer explicitly to avoid declaring an array at file >>> > > scope. >>> > > >>> > > Cc: H.J. Lu >>> > > Signed-off-by: Stefan Hajnoczi >>> > > --- >>> > > Perhaps the glibc change needs to be revised before releasing glibc 2.34 >>> > > since it might break applications. That's up to the glibc folks. It >>> > > doesn't hurt for liburing to take a safer approach that copes with the >>> > > SIGSTKSZ change in any case. >>> > >>> > glibc folks, please take a look. The commit referenced above broke >>> > compilation of liburing's tests. It's possible that applications will >>> > hit similar issues. Can you check whether the SIGSTKSZ change needs to >>> > be reverted/fixed before releasing glibc 2.34? >>> > >>> >>> It won't be changed for glibc 2.34. >> >> Thanks for the response, H.J. and Paul. >> >> In that case liburing needs this patch. >> > > I think so: > > Reviewed-by: Stefano Garzarella Right, and there are already people complaining https://github.com/axboe/liburing/issues/320 -- Pavel Begunkov