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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 09A0DC433E2 for ; Wed, 15 Jul 2020 23:20:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D04D42067D for ; Wed, 15 Jul 2020 23:20:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594855214; bh=JESx7qOGoSMwajK8A+uKWD0Dl16XVysyJGtAAJzP2UU=; h=From:To:Cc:Subject:Date:List-ID:From; b=N+bhRaNo1TCui8tbOxbVbucAMZ6BVNG9G2LX9R178y5B8WBPEDutTno4daPLXUhBF Qpr1PqHjRVXcwDaCCrMeE8VShEHeusAp/aKzc0KEzaN+dV1Pzcm8y686mgFArGaLv4 9jB43Kghe5uf78VN/d1y/pyX+wN9TsDVzARbmhHY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726989AbgGOXUN (ORCPT ); Wed, 15 Jul 2020 19:20:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:57318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726770AbgGOXUN (ORCPT ); Wed, 15 Jul 2020 19:20:13 -0400 Received: from lenoir.home (lfbn-ncy-1-317-216.w83-196.abo.wanadoo.fr [83.196.152.216]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6ED7F20658; Wed, 15 Jul 2020 23:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594855212; bh=JESx7qOGoSMwajK8A+uKWD0Dl16XVysyJGtAAJzP2UU=; h=From:To:Cc:Subject:Date:From; b=g/k3idTIXDydfxSbSIz+xC7jq0czGH/kuT/yXF7YegNV9OXvgXbLH8iwB7w0a6Fez 4eg6A+TauLBycBDv3DVWMGID847IfCQ2ZS5lasMWoXnxepj4HWAyxNr3cHmeqF2TT7 Ecg/+BzsZCL1l7kjg6SNHWbhZzUeyf+zg4V35xek= From: Frederic Weisbecker To: Thomas Gleixner Cc: LKML , Frederic Weisbecker , Peter Zijlstra , Juri Lelli , stable@vger.kernel.org, Anna-Maria Behnsen Subject: [PATCH] timer: Fix wheel index calculation on last level Date: Thu, 16 Jul 2020 01:20:06 +0200 Message-Id: <20200715232006.26791-1-frederic@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When an expiration delta falls into the last level of the wheel, we want to compare that delta against the maximum possible delay and reduce our delta to fit in if necessary. However instead of comparing the delta against the maximum, we are comparing the actual expiry against the maximum. Then instead of fixing the delta to fit in, we set the maximum delta as the expiry value. This can result in various undesired outcomes, the worst possible one being a timer expiring 15 days ahead to fire immediately. Fixes: 500462a9de65 ("timers: Switch to a non-cascading wheel") Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Anna-Maria Behnsen Cc: Juri Lelli Cc: Thomas Gleixner Cc: stable@vger.kernel.org --- kernel/time/timer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 9a838d38dbe6..df1ff803acc4 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -521,8 +521,8 @@ static int calc_wheel_index(unsigned long expires, unsigned long clk) * Force expire obscene large timeouts to expire at the * capacity limit of the wheel. */ - if (expires >= WHEEL_TIMEOUT_CUTOFF) - expires = WHEEL_TIMEOUT_MAX; + if (delta >= WHEEL_TIMEOUT_CUTOFF) + expires = clk + WHEEL_TIMEOUT_MAX; idx = calc_index(expires, LVL_DEPTH - 1); } -- 2.26.2