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 51ECDC7618D for ; Wed, 15 Mar 2023 23:45:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232524AbjCOXpL (ORCPT ); Wed, 15 Mar 2023 19:45:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43580 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233354AbjCOXpA (ORCPT ); Wed, 15 Mar 2023 19:45:00 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 641AD13537; Wed, 15 Mar 2023 16:44:35 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id AD5ABB81E8F; Wed, 15 Mar 2023 23:43:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9067C433D2; Wed, 15 Mar 2023 23:43:37 +0000 (UTC) Date: Wed, 15 Mar 2023 19:43:34 -0400 From: Steven Rostedt To: Florent Revest Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, mhiramat@kernel.org, mark.rutland@arm.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kpsingh@kernel.org, jolsa@kernel.org, xukuohai@huaweicloud.com, lihuafei1@huawei.com Subject: Re: [PATCH v2 04/10] ftrace: Store direct called addresses in their ops Message-ID: <20230315194334.58eb56ab@gandalf.local.home> In-Reply-To: <20230207182135.2671106-5-revest@chromium.org> References: <20230207182135.2671106-1-revest@chromium.org> <20230207182135.2671106-5-revest@chromium.org> X-Mailer: Claws Mail 3.17.8 (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, 7 Feb 2023 19:21:29 +0100 Florent Revest wrote: > @@ -5445,6 +5445,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > /* Enable the tmp_ops to have the same functions as the direct ops */ > ftrace_ops_init(&tmp_ops); > tmp_ops.func_hash = ops->func_hash; > + tmp_ops.direct_call = addr; > > err = register_ftrace_function_nolock(&tmp_ops); > if (err) > @@ -5466,6 +5467,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > entry->direct = addr; > } > } > + WRITE_ONCE(ops->direct_call, addr); I'm curious about the use of WRITE_ONCE(). It should not go outside the mutex barrier. -- Steve > > mutex_unlock(&ftrace_lock); >