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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 E9393C282C8 for ; Mon, 28 Jan 2019 16:08:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC08B20856 for ; Mon, 28 Jan 2019 16:08:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548691731; bh=P/9susO6JXRHQi1Ay1pwjAQT6Xqj82L8fUkhh6zd0Ls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0x752y/eUDXKbx8WFYmOH7v6MB+mTag/CbjNxll2IVedHLm5HiuaZf3VYtROdkNc7 xqeL7lBwtVshiNXww46187gVa0p3yeSH1ivkioG7goMKySeVHZycGPX4WbIAR1nony Awt0KCYLoGfYoQMdnhz7uXv27RGR6QkbM8M/3SRQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732486AbfA1QIu (ORCPT ); Mon, 28 Jan 2019 11:08:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:60968 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731323AbfA1QIt (ORCPT ); Mon, 28 Jan 2019 11:08:49 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 C8D652171F; Mon, 28 Jan 2019 16:08:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548691728; bh=P/9susO6JXRHQi1Ay1pwjAQT6Xqj82L8fUkhh6zd0Ls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TYA5VNIdeRoJXONTDvjJ3lZZRTCaDScV0VNNq53HG8JvZ6stBGPtPD9QBeLxZkems SGnFfB0ssXxJ7WX+X4U74dTbd9yt05DGTHXm4KGgxZwjJ5V/H15iuxd/nLkxY2II/G beAYjBBCKHhjwAvJ7bpOs94wORUqHw8xeCSDWkCk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miroslav Lichvar , Richard Cochran , Ariel Levkovich , Saeed Mahameed , Sasha Levin , netdev@vger.kernel.org, linux-rdma@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 198/258] mlx5: update timecounter at least twice per counter overflow Date: Mon, 28 Jan 2019 10:58:24 -0500 Message-Id: <20190128155924.51521-198-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128155924.51521-1-sashal@kernel.org> References: <20190128155924.51521-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miroslav Lichvar [ 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 3f767cde4c1d..54f1a40a68ed 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