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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,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 F04FFC28CC1 for ; Sat, 1 Jun 2019 13:25:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFDAA273A0 for ; Sat, 1 Jun 2019 13:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559395555; bh=42LW48W8DZcCEbLw6HOz3/Nm4Q8vo0BU67ftoLZtpWA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OJgUSXW43447SHfjBuWMXzH2/f20ZAtXyxoCVY6Oi9D10jKLk9EWVQYQLHXnXYm7I fnJyioFKMQpf18bqCWlEHumCKX2NnUI6iLWGQ3DyUtcuko/br/f0E3xPY6u6PcRyH1 BFJ+PgCM7U0G0D8Lq7q3dDG77ImGpcNFs0H5d3WU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727937AbfFANZz (ORCPT ); Sat, 1 Jun 2019 09:25:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:56160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729230AbfFANZq (ORCPT ); Sat, 1 Jun 2019 09:25:46 -0400 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 8351D27396; Sat, 1 Jun 2019 13:25:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559395545; bh=42LW48W8DZcCEbLw6HOz3/Nm4Q8vo0BU67ftoLZtpWA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oUuIguc79E8VwFBInSkNV8MG3Z3xyZnlb/Y1cLF2GSRGu/oyhlDfUQ2LibIeSS4KV djTemswDyY83N+JtY44jLX0V8Xci9uWkJQWvwpcsAGx1He1b19/rsIRcr0nV5xHK8z KSjdfqfaJ9Wo8X1fFdK7hC3WJ6rfiUgWfZymMuYo= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miroslav Lichvar , Ondrej Mosnacek , Thomas Gleixner , John Stultz , Richard Cochran , Prarit Bhargava , Sasha Levin Subject: [PATCH AUTOSEL 4.9 21/74] ntp: Allow TAI-UTC offset to be set to zero Date: Sat, 1 Jun 2019 09:24:08 -0400 Message-Id: <20190601132501.27021-21-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190601132501.27021-1-sashal@kernel.org> References: <20190601132501.27021-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review 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 fdc6bae940ee9eb869e493990540098b8c0fd6ab ] The ADJ_TAI adjtimex mode sets the TAI-UTC offset of the system clock. It is typically set by NTP/PTP implementations and it is automatically updated by the kernel on leap seconds. The initial value is zero (which applications may interpret as unknown), but this value cannot be set by adjtimex. This limitation seems to go back to the original "nanokernel" implementation by David Mills. Change the ADJ_TAI check to accept zero as a valid TAI-UTC offset in order to allow setting it back to the initial value. Fixes: 153b5d054ac2 ("ntp: support for TAI") Suggested-by: Ondrej Mosnacek Signed-off-by: Miroslav Lichvar Signed-off-by: Thomas Gleixner Cc: John Stultz Cc: Richard Cochran Cc: Prarit Bhargava Link: https://lkml.kernel.org/r/20190417084833.7401-1-mlichvar@redhat.com Signed-off-by: Sasha Levin --- kernel/time/ntp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 6df8927c58a5b..0a16419006f3b 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -639,7 +639,7 @@ static inline void process_adjtimex_modes(struct timex *txc, time_constant = max(time_constant, 0l); } - if (txc->modes & ADJ_TAI && txc->constant > 0) + if (txc->modes & ADJ_TAI && txc->constant >= 0) *time_tai = txc->constant; if (txc->modes & ADJ_OFFSET) -- 2.20.1