From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9186 invoked by alias); 30 Apr 2014 12:58:39 -0000 Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org Received: (qmail 9095 invoked by uid 89); 30 Apr 2014 12:58:38 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-qc0-f174.google.com Received: from mail-qc0-f174.google.com (HELO mail-qc0-f174.google.com) (209.85.216.174) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Wed, 30 Apr 2014 12:58:36 +0000 Received: by mail-qc0-f174.google.com with SMTP id c9so1784457qcz.33 for ; Wed, 30 Apr 2014 05:58:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=+URaSzEmnrS/IDB4geKse0lqFldv6tM4ysO4FKk3GTo=; b=KAeyEPAMD3FfXY1/c5vihxUevSLBR2nY04PoQUAsBxXkPB7480nE28Tk7ZDSsDHmIj qrj6X55YODRM4uPHV3tLo9KwDE4IOt5ViepCnlOw/5ox2obHvM2HxRPUdUKGzuCrTMWF gUtl6JjfqSxXFpcuFoI4u3UegPQaYK6pfHUn+b9heFKndA6cTGovELCh4I2dBfkqSSqY eHhiGtyVZlOhKUIsl+uCb0B0OOwvg/5Nq/n8jGEgIm8L8W6km3PyJocczlDAqf6R4Ods il7LP7Cr1sns9hzCbt5QVq1nEJmXCbMy7WuulDVeU1gU3BQCQzT3a+PEKV4/aBiL5O/H 2iBg== X-Gm-Message-State: ALoCoQklw9n3Dm7va28d77KG0HE+mptGvZtctPbUMr6QGuT2j6m8GSzZvr/yoVYCfNK6CQ4htMkf MIME-Version: 1.0 X-Received: by 10.229.214.74 with SMTP id gz10mr4910219qcb.19.1398862713819; Wed, 30 Apr 2014 05:58:33 -0700 (PDT) Received: by 10.96.152.200 with HTTP; Wed, 30 Apr 2014 05:58:33 -0700 (PDT) In-Reply-To: References: Date: Wed, 30 Apr 2014 12:58:00 -0000 Message-ID: Subject: Re: [PATCH] Remove arm lowlevellock.c From: Bernie Ogden To: "Joseph S. Myers" Cc: Will Newton , "libc-ports@sourceware.org" , libc-alpha Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2014-04/txt/msg00015.txt.bz2 The workaround is that some of the arm lowlevellock.c functions promote futex to 2 if it is 1. Generic lowlevellock.c always promotes futex to 2. Hence, removing arm's lowlevellock.c doesn't cause a regression in this sense. It does mean that arm stops being affected by BZ 15119 and instead is affected by the second bug. So we go from having BZ 15119 on arm, and a second bug on aarch64, m68k and sh/sh4, to having the second bug across all of these platforms. That feels like progress to me, but you could reasonably differ. I agree with you on unifying lowlevellock.h - so it'll take a little longer for me to submit the fix for the second bug as I'll stop to unify the files as part of the work. (Quite a few of them do look unifiable.) I guess I should create something in bugzilla for 'the second bug' - I'll go do that soon. On 29 April 2014 16:26, Joseph S. Myers wrote: > On Mon, 28 Apr 2014, Will Newton wrote: > >> Hi Bernie, >> >> ARM patches can now be sent to libc-alpha as ARM has moved from ports >> into the main tree. >> >> I'm not sure if we still use libc-ports for HPPA patches... >> >> On 28 April 2014 15:50, Bernie Ogden wrote: >> > lowlevellock.c for arm differs from the generic lowlevellock.c only in >> > insignificant ways, so can be removed. Happily, this fixes BZ 15119 >> > (unnecessary busy loop in __lll_timedlock_wait on arm). > > ... > >> > Also note that the analysis at >> > https://sourceware.org/ml/libc-ports/2013-02/msg00021.html indicates a >> > further locking performance bug to fix - I've got a partial patch for >> > that which I can submit once I've finished testing. > > That analysis asserts that ARM's lowlevellock.c is trying to work around > a bug in lowlevellock.h. Are you asserting in this patch that in fact the > workaround is not needed - that there is no regression caused by removing > the lowlevellock.c file before fixing the lowlevellock.h bug? > > (Actually I'd like to see unification of the lowlevellock.h files as far > as possible, not just lowlevellock.c.) > > -- > Joseph S. Myers > joseph@codesourcery.com