From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756281AbbLANmm (ORCPT ); Tue, 1 Dec 2015 08:42:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46584 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754914AbbLANmj (ORCPT ); Tue, 1 Dec 2015 08:42:39 -0500 Date: Tue, 1 Dec 2015 14:42:36 +0100 From: Jiri Olsa To: Steven Rostedt Cc: LKML , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH] ftrace: Remove use of control list and ops Message-ID: <20151201134213.GA14155@krava.brq.redhat.com> References: <20151130173640.2c45b429@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151130173640.2c45b429@gandalf.local.home> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 30, 2015 at 05:36:40PM -0500, Steven Rostedt wrote: > > [ Jiri, can you take a look at this. You can also apply it on top of my > branch ftrace/core, and run any specific tests. I just need to nuke > that control structure for further updates with ftrace. ] > > > Currently perf has its own list function within the ftrace infrastructure > that seems to be used only to allow for it to have per-cpu disabling as well > as a check to make sure that it's not called while RCU is not watching. It > uses something called the "control_ops" which is used to iterate over ops > under it with the control_list_func(). > > The problem is that this control_ops and control_list_func unnecessarily > complicates the code. By replacing FTRACE_OPS_FL_CONTROL with two new flags > (FTRACE_OPS_FL_RCU and FTRACE_OPS_FL_PER_CPU) we can remove all the code > that is special with the control ops and add the needed checks within the > generic ftrace_list_func(). hum, do we need also change for the trampoline, something like below? I needed attached patch to get the perf ftrace:function event work properly.. thanks, jirka --- diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index c4d881200d1f..2705ac2f3487 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5179,6 +5179,26 @@ static void ftrace_ops_recurs_func(unsigned long ip, unsigned long parent_ip, trace_clear_recursion(bit); } +static void ftrace_ops_per_cpu_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs) +{ + int bit; + + bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX); + if (bit < 0) + return; + + preempt_disable_notrace(); + + if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) && + (!(op->flags & FTRACE_OPS_FL_PER_CPU) || !ftrace_function_local_disabled(op))) { + op->func(ip, parent_ip, op, regs); + } + + preempt_enable_notrace(); + trace_clear_recursion(bit); +} + /** * ftrace_ops_get_func - get the function a trampoline should call * @ops: the ops to get the function for @@ -5192,6 +5212,11 @@ static void ftrace_ops_recurs_func(unsigned long ip, unsigned long parent_ip, */ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops) { + if (ops->flags & (FTRACE_OPS_FL_PER_CPU|FTRACE_OPS_FL_RCU)) { + printk("used per cpu trampoline function\n"); + return ftrace_ops_per_cpu_func; + } + /* * If the func handles its own recursion, call it directly. * Otherwise call the recursion protected function that