From patchwork Fri Jan 17 17:41:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 213276 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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=unavailable 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 1C8B4C33CB3 for ; Fri, 17 Jan 2020 17:42:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBDE6246B1 for ; Fri, 17 Jan 2020 17:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729133AbgAQRlb (ORCPT ); Fri, 17 Jan 2020 12:41:31 -0500 Received: from mail.kernel.org ([198.145.29.99]:40074 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729110AbgAQRla (ORCPT ); Fri, 17 Jan 2020 12:41:30 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 0157D217F4; Fri, 17 Jan 2020 17:41:30 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1isVce-000QRF-TP; Fri, 17 Jan 2020 12:41:28 -0500 Message-Id: <20200117174128.792272889@goodmis.org> User-Agent: quilt/0.65 Date: Fri, 17 Jan 2020 12:41:21 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Julia Cartwright , Daniel Wagner , Tom Zanussi , Julien Grall Subject: [PATCH RT 10/32] hrtimer: Prevent using hrtimer_grab_expiry_lock() on migration_base References: <20200117174111.282847363@goodmis.org> MIME-Version: 1.0 Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org 4.19.94-rt39-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Julien Grall [ Upstream commit cef1b87f98823af923a386f3f69149acb212d4a1 ] As tglx puts it: |If base == migration_base then there is no point to lock soft_expiry_lock |simply because the timer is not executing the callback in soft irq context |and the whole lock/unlock dance can be avoided. Furthermore, all the path leading to hrtimer_grab_expiry_lock() assumes timer->base and timer->base->cpu_base are always non-NULL. So it is safe to remove the NULL checks here. Signed-off-by: Julien Grall Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908211557420.2223@nanos.tec.linutronix.de Signed-off-by: Steven Rostedt (VMware) [bigeasy: rewrite changelog] Signed-off-by: Sebastian Andrzej Siewior --- kernel/time/hrtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 49d20fe8570f..1a5167c68310 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -943,7 +943,7 @@ void hrtimer_grab_expiry_lock(const struct hrtimer *timer) { struct hrtimer_clock_base *base = READ_ONCE(timer->base); - if (timer->is_soft && base && base->cpu_base) { + if (timer->is_soft && base != &migration_base) { spin_lock(&base->cpu_base->softirq_expiry_lock); spin_unlock(&base->cpu_base->softirq_expiry_lock); }