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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 406FFC2B9F4 for ; Tue, 22 Jun 2021 23:42:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2464A611CA for ; Tue, 22 Jun 2021 23:42:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230040AbhFVXo3 (ORCPT ); Tue, 22 Jun 2021 19:44:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:52730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229747AbhFVXo1 (ORCPT ); Tue, 22 Jun 2021 19:44:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3F4756135A; Tue, 22 Jun 2021 23:42:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624405330; bh=Pp7IXW9CuTZ/eAAexklW/FU0iA9vx3eezutjba+V8js=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=owdMhLV8JBllX74HI2RPdjnCKx1vh9k0Jy2wUlIkS7gNDdubmC6Q0Dhfj8MM+LIqf kFBJcTMOM6s3MrdvHSxUL/uCDo1WHNbNbii6Z+FU9MDZwLRMCLgE20lo38h5zK8RU8 89in7GR7Jzv2ZOXQqF88760iucrw71FdOpxsWy4/h7UggErudcjfevgmATB5sRa+py 7oytwJoyH424RWbtkXMdjB1SM1bKmYYib7lMND0ad/VprEOE3H0XT8wKbNmaMj0kX6 PZJeR20NHKAWsNEqZbgP9SRpSCqnV+bg9IlaXXllFmkhCIFDQPADg2oDMPATel1JcQ XcAtW2vici6rw== From: Frederic Weisbecker To: Thomas Gleixner , Peter Zijlstra Cc: LKML , Frederic Weisbecker , "Eric W . Biederman" , Oleg Nesterov , Ingo Molnar Subject: [PATCH 4/7] posix-cpu-timers: Force next expiration recalc after itimer reset Date: Wed, 23 Jun 2021 01:41:52 +0200 Message-Id: <20210622234155.119685-5-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210622234155.119685-1-frederic@kernel.org> References: <20210622234155.119685-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When an itimer deactivates a previously armed expiration, it simply doesn't do anything. As a result the process wide cputime counter keeps running and the tick dependency stays set until we reach the old ghost expiration value. This can be reproduced with the following snippet: void trigger_process_counter(void) { struct itimerval n = {}; n.it_value.tv_sec = 100; setitimer(ITIMER_VIRTUAL, &n, NULL); n.it_value.tv_sec = 0; setitimer(ITIMER_VIRTUAL, &n, NULL); } Fix this with resetting the relevant base expiration. This is similar to disarming a timer. Signed-off-by: Frederic Weisbecker Cc: Oleg Nesterov Cc: Thomas Gleixner Cc: Peter Zijlstra (Intel) Cc: Ingo Molnar Cc: Eric W. Biederman --- kernel/time/posix-cpu-timers.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 13939f47c7b0..cc9f8be67694 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1379,8 +1379,6 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid, } } - if (!*newval) - return; *newval += now; } -- 2.25.1