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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no 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 5B683C4338F for ; Tue, 10 Aug 2021 19:14:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35A0461052 for ; Tue, 10 Aug 2021 19:14:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231764AbhHJTO7 (ORCPT ); Tue, 10 Aug 2021 15:14:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:38990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230295AbhHJTO6 (ORCPT ); Tue, 10 Aug 2021 15:14:58 -0400 Received: from oasis.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 2468561019; Tue, 10 Aug 2021 19:14:35 +0000 (UTC) Date: Tue, 10 Aug 2021 15:14:28 -0400 From: Steven Rostedt To: Sebastian Andrzej Siewior Cc: Clark Williams , Thomas Gleixner , Dmitry Vyukov , Andrey Konovalov , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH PREEMPT_RT] kcov: fix locking splat from kcov_remote_start() Message-ID: <20210810151428.3e02d386@oasis.local.home> In-Reply-To: <20210810095032.epdhivjifjlmbhp5@linutronix.de> References: <20210809155909.333073de@theseus.lan> <20210810095032.epdhivjifjlmbhp5@linutronix.de> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Aug 2021 11:50:32 +0200 Sebastian Andrzej Siewior wrote: > - With lock kcov_remote_lock acquired there is a possible > hash_for_each_safe() and list_for_each() iteration. I don't know what > the limits are here but with a raw_spinlock_t it will contribute to > the maximal latency. Note, anyone having a kernel with KCOV compiled in, probably doesn't care about latency ;-) It's like worrying about latency when lockdep is complied in. -- Steve