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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 0E833C169C4 for ; Mon, 11 Feb 2019 14:31:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D233F20675 for ; Mon, 11 Feb 2019 14:31:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549895496; bh=9hVn75N3LPSjsv3h8GF57VsxqxoZ7Po5V16rZH7lrVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FWSaXqpN8C5Sk7B5unjb/5xGCjCjM1QLPY6dPATdEYyyAdPfYybUauwn9/ywv8xqe Fm3vm0EHSRtx9bLsW9GpoWjBlnAGpiZToFvdVeeixVY6GRd2N5Q1oqVH70hNvnoAJG 5DRzJeYG5XvbZzpRNiCjbNe+GbBPAXd6JMUIQ/AE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729991AbfBKObf (ORCPT ); Mon, 11 Feb 2019 09:31:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:38548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730325AbfBKObe (ORCPT ); Mon, 11 Feb 2019 09:31:34 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A125820844; Mon, 11 Feb 2019 14:31:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549895494; bh=9hVn75N3LPSjsv3h8GF57VsxqxoZ7Po5V16rZH7lrVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H3oYFeGntiXGEvrq1bMe9pHKxhbAA7VZkNkO8CepK0qx/JycOMyzoYUVt6kLpKDq1 cRDtjzsDyRBZo/tbfeemKgEfzPe2ECCWTzxbvcjEfakRCw1Cg6dT2UnJoqp/HUjgPz I8nLWjSw45HSi8QISARy2UWQN67GMYBs+2z1jIFw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Richard Cochran , Ariel Levkovich , Saeed Mahameed , Miroslav Lichvar , Sasha Levin Subject: [PATCH 4.20 224/352] mlx5: update timecounter at least twice per counter overflow Date: Mon, 11 Feb 2019 15:17:31 +0100 Message-Id: <20190211141901.475896932@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190211141846.543045703@linuxfoundation.org> References: <20190211141846.543045703@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 5d8678365c90b9ce1fd2243ff5ea562609f6cec1 ] The timecounter needs to be updated at least once in half of the cyclecounter interval to prevent timecounter_cyc2time() interpreting a new timestamp as an old value and causing a backward jump. This would be an issue if the timecounter multiplier was so small that the update interval would not be limited by the 64-bit overflow in multiplication. Shorten the calculated interval to make sure the timecounter is updated in time even when the system clock is slowed down by up to 10%, the multiplier is increased by up to 10%, and the scheduled overflow check is late by 15%. Cc: Richard Cochran Cc: Ariel Levkovich Cc: Saeed Mahameed Signed-off-by: Miroslav Lichvar Signed-off-by: Saeed Mahameed Signed-off-by: Sasha Levin --- drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c index 0d90b1b4a3d3..2d6168ee99e8 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c @@ -511,14 +511,14 @@ void mlx5_init_clock(struct mlx5_core_dev *mdev) ktime_to_ns(ktime_get_real())); /* Calculate period in seconds to call the overflow watchdog - to make - * sure counter is checked at least once every wrap around. + * sure counter is checked at least twice every wrap around. * The period is calculated as the minimum between max HW cycles count * (The clock source mask) and max amount of cycles that can be * multiplied by clock multiplier where the result doesn't exceed * 64bits. */ overflow_cycles = div64_u64(~0ULL >> 1, clock->cycles.mult); - overflow_cycles = min(overflow_cycles, clock->cycles.mask >> 1); + overflow_cycles = min(overflow_cycles, div_u64(clock->cycles.mask, 3)); ns = cyclecounter_cyc2ns(&clock->cycles, overflow_cycles, frac, &frac); -- 2.19.1