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=-12.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS 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 BF6B8C43219 for ; Mon, 29 Apr 2019 06:40:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D35C21670 for ; Mon, 29 Apr 2019 06:40:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="q+/09MRx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727440AbfD2Gk2 (ORCPT ); Mon, 29 Apr 2019 02:40:28 -0400 Received: from terminus.zytor.com ([198.137.202.136]:38205 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726589AbfD2Gk1 (ORCPT ); Mon, 29 Apr 2019 02:40:27 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x3T6d6l4784096 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 28 Apr 2019 23:39:06 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x3T6d6l4784096 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041745; t=1556519947; bh=By94weL1iGn8VcVcN5ZCjzI7uVWC8EfRyQlB+QhIaoo=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=q+/09MRx80XlaRETuhqFUi909cc4zGPVBD0Fic745VWOQ0l4XyfgYr9DLSyOIMjNN xkWutV2/F+ZqBrToEx6USQ8I2ZgS1OTuiw8IDEScVuIfBfec928EhBLSESwwPRxuYP vaKndPl6+HFr/7qKL63svjOMmUZz+buE14U6O1QSXEuwWuVuvZQMSwnw8mveWxhI4l ueDMlpbWw+15LyVXeZmmBb5+Ta0dbM58JFO9npNPVyF9tDhazSuHR4O7HRz6l+mCra Unos/B1MsKWeIa2yG/paSi5cuK6G3xzng5FLxoIVIWvmouMvpXcLuCG6ZGyEzx27Mz qTOzV5ZB8+gKw== Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x3T6d3MJ784077; Sun, 28 Apr 2019 23:39:03 -0700 Date: Sun, 28 Apr 2019 23:39:03 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Peter Zijlstra Message-ID: Cc: ast@kernel.org, rostedt@goodmis.org, tim.c.chen@linux.intel.com, dave@stgolabs.net, hpa@zytor.com, peterz@infradead.org, guro@fb.com, linux-kernel@vger.kernel.org, mingo@kernel.org, tglx@linutronix.de, daniel@iogearbox.net, huang.ying.caritas@gmail.com, will.deacon@arm.com, longman@redhat.com, torvalds@linux-foundation.org Reply-To: linux-kernel@vger.kernel.org, mingo@kernel.org, guro@fb.com, peterz@infradead.org, hpa@zytor.com, dave@stgolabs.net, tim.c.chen@linux.intel.com, rostedt@goodmis.org, ast@kernel.org, torvalds@linux-foundation.org, longman@redhat.com, will.deacon@arm.com, huang.ying.caritas@gmail.com, daniel@iogearbox.net, tglx@linutronix.de In-Reply-To: <20190423200318.GY14281@hirez.programming.kicks-ass.net> References: <20190423200318.GY14281@hirez.programming.kicks-ass.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] trace: Fix preempt_enable_no_resched() abuse Git-Commit-ID: e8bd5814989b994cf1b0cb179e1c777e40c0f02c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: e8bd5814989b994cf1b0cb179e1c777e40c0f02c Gitweb: https://git.kernel.org/tip/e8bd5814989b994cf1b0cb179e1c777e40c0f02c Author: Peter Zijlstra AuthorDate: Tue, 23 Apr 2019 22:03:18 +0200 Committer: Ingo Molnar CommitDate: Mon, 29 Apr 2019 08:27:09 +0200 trace: Fix preempt_enable_no_resched() abuse Unless there is a call into schedule() in the immediate (deterministic) future, one must not use preempt_enable_no_resched(). It can cause a preemption to go missing and thereby cause arbitrary delays, breaking the PREEMPT=y invariant. Signed-off-by: Peter Zijlstra (Intel) Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Davidlohr Bueso Cc: Linus Torvalds Cc: Roman Gushchin Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Tim Chen Cc: Waiman Long Cc: Will Deacon Cc: huang ying Fixes: 2c2d7329d8af ("tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()") Link: https://lkml.kernel.org/r/20190423200318.GY14281@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/trace/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 41b6f96e5366..4ee8d8aa3d0f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -762,7 +762,7 @@ u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) preempt_disable_notrace(); time = rb_time_stamp(buffer); - preempt_enable_no_resched_notrace(); + preempt_enable_notrace(); return time; }