From nobody Thu Sep 18 04:52:31 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79E0AC4332F for ; Wed, 14 Dec 2022 14:02:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238537AbiLNOCT (ORCPT ); Wed, 14 Dec 2022 09:02:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238518AbiLNOCL (ORCPT ); Wed, 14 Dec 2022 09:02:11 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66BD522BC5 for ; Wed, 14 Dec 2022 06:02:11 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0108D61AA0 for ; Wed, 14 Dec 2022 14:02:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69A15C433AC; Wed, 14 Dec 2022 14:02:10 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1p5SKn-000gvH-1Y; Wed, 14 Dec 2022 09:02:09 -0500 Message-ID: <20221214140209.346584113@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 14 Dec 2022 09:01:39 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Mark Rutland , "Guilherme G. Piccoli" Subject: [for-next][PATCH 6/8] ftrace: Prevent RCU stall on PREEMPT_VOLUNTARY kernels References: <20221214140133.608431204@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "gpiccoli@igalia.com" The function match_records() may take a while due to a large number of string comparisons, so when in PREEMPT_VOLUNTARY kernels we could face RCU stalls due to that. Add a cond_resched() to prevent that. Link: https://lkml.kernel.org/r/20221115204847.593616-1-gpiccoli@igalia.com Cc: Mark Rutland Suggested-by: Steven Rostedt Acked-by: Paul E. McKenney # from RCU CPU stall warnin= g perspective Signed-off-by: Guilherme G. Piccoli Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d04552c0c275..b8e374a372e5 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4204,6 +4204,7 @@ match_records(struct ftrace_hash *hash, char *func, i= nt len, char *mod) } found =3D 1; } + cond_resched(); } while_for_each_ftrace_rec(); out_unlock: mutex_unlock(&ftrace_lock); --=20 2.35.1