From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by dpdk.org (Postfix) with ESMTP id 1559E2E41 for ; Mon, 3 Aug 2015 00:07:53 +0200 (CEST) Received: by wibxm9 with SMTP id xm9so91496371wib.1 for ; Sun, 02 Aug 2015 15:07:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=uMgWyhrbW8ty+M0+keNyVQ6enz1lcy3ML4qFtCKVKGw=; b=f9MIowHkJqTxo6Rs6J5AoSZ8lXOf3DbHTPHmgTWJqcBPCdhoIz2gk0Y2oi8TgrmPrB 1ZXpxg2ZJ6IRj0z/IB4m70l23orBPfQtpBMol9cI9z3MQf91KUdn8biH0GhDi5A8UeAU Jdx5hH3LB84Rnzr6WjyRBjdvE1czaat9JVMEqA5bzeh2MCNmx0i/0ueMqdRjRoTqcgqW 1TZlnZet+saxyi6LCQYmOPheroZsvRM3AuNW5bn6mveva9cohbb30VdznzOjHFwqgVqY 4gj8BRIDEUiddYqvHOvZvBrQ0lKE+k0SMgkmf1P/1bCgz9hTiXMSJB8zsN+wBDtG+yb1 RH8A== X-Gm-Message-State: ALoCoQkGQ11nNj7K3PBQttoxDbgd79i3CjDywzzY6D9TbSZpvxZTUrEmSv/nVnHuPv+5/FjF6w2h X-Received: by 10.180.36.3 with SMTP id m3mr28801410wij.60.1438553272787; Sun, 02 Aug 2015 15:07:52 -0700 (PDT) Received: from xps13.localnet (136-92-190-109.dsl.ovh.fr. [109.190.92.136]) by smtp.gmail.com with ESMTPSA id lq9sm19527211wjb.35.2015.08.02.15.07.51 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 02 Aug 2015 15:07:52 -0700 (PDT) From: Thomas Monjalon To: rsanford2@gmail.com Date: Mon, 03 Aug 2015 00:06:38 +0200 Message-ID: <1803527.ArLAiIq7YK@xps13> Organization: 6WIND User-Agent: KMail/4.14.8 (Linux/4.0.4-2-ARCH; KDE/4.14.8; x86_64; ; ) In-Reply-To: <1438037168-639-1-git-send-email-rsanford2@gmail.com> References: <1437691347-58708-1-git-send-email-rsanford2@gmail.com> <1438037168-639-1-git-send-email-rsanford2@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v2 0/3] timer: fix rte_timer_manage and improve unit tests X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Aug 2015 22:07:53 -0000 2015-07-27 18:46, rsanford2@gmail.com: > From: Robert Sanford > > This patchset fixes a bug in timer stress test 2, adds a new stress test > to expose a race condition bug in API rte_timer_manage(), and then fixes > the rte_timer_manage() bug. > > Description of rte_timer_manage() race condition bug: Through code > inspection, we notice a potential problem in rte_timer_manage() that > leads to corruption of per-lcore pending-lists (implemented as > skip-lists). The race condition occurs when rte_timer_manage() expires > multiple timers on lcore A, while lcore B simultaneously invokes > rte_timer_reset() for one of the expiring timers (other than the first > one). > > Lcore A splits its pending-list, creating a local list of expired timers > linked through their sl_next[0] pointers, and sets the first expired > timer to the RUNNING state, all during one list-lock round trip. > Lcore A then unlocks the list-lock to run the first callback, and that > is when A and B can have different interpretations of the subsequent > expired timers' true state. Lcore B sees an expired timer still in the > PENDING state, atomically changes the timer to the CONFIG state, locks > lcore A's list-lock, and reinserts the timer into A's pending-list. > The two lcores try to use the same next-pointers to maintain both lists! > > v2 changes: > Move patch descriptions to their respective patches. > Correct checkpatch warnings. Applied, thanks