From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755858AbbLAQ5A (ORCPT ); Tue, 1 Dec 2015 11:57:00 -0500 Received: from smtprelay0224.hostedemail.com ([216.40.44.224]:40659 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750931AbbLAQ46 (ORCPT ); Tue, 1 Dec 2015 11:56:58 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1542:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2553:2559:2562:2693:2897:3138:3139:3140:3141:3142:3354:3622:3865:3866:3867:3868:3871:3872:3873:3874:4250:4321:5007:6119:6261:7875:7903:8660:9010:9012:9038:10004:10400:10848:10967:11026:11232:11473:11658:11914:12043:12296:12438:12517:12519:12555:12663:12740:13148:13230:13972:14096:14097:14659:21080:30012:30054:30070:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:3,LUA_SUMMARY:none X-HE-Tag: route21_25f70bb2842c X-Filterd-Recvd-Size: 3701 Date: Tue, 1 Dec 2015 11:56:55 -0500 From: Steven Rostedt To: Jiri Olsa Cc: LKML , Ingo Molnar , Peter Zijlstra Subject: Re: [PATCH] ftrace: Remove use of control list and ops Message-ID: <20151201115655.1b7e79e6@gandalf.local.home> In-Reply-To: <20151201155744.GA24786@krava.local> References: <20151130173640.2c45b429@gandalf.local.home> <20151201134213.GA14155@krava.brq.redhat.com> <20151201095554.7b56bff7@gandalf.local.home> <20151201155744.GA24786@krava.local> X-Mailer: Claws Mail 3.13.0 (GTK+ 2.24.28; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 1 Dec 2015 16:57:44 +0100 Jiri Olsa wrote: > > Hmm, I thought that I forced the list function when RCU or PER_CPU > > was set. Oh wait. I have CONFIG_PREEMPT set, which will change the > > logic slightly. I'm guessing you have PREEMPT_VOLUNTARY set. I'll try > > that out. > > yep, but the trampoline has separate code path > to set the ops func Right, but that only gets called for DYNAMIC ops (which perf is) when CONFIG_PREEMPT is not set. What about this patch instead? (on top of my other one) It's a lot like yours, but instead of creating a new helper function, I just reuse the recurs_func instead. -- Steve diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 8b22e681baf8..05ed87d06bb0 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5230,20 +5230,29 @@ static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip) /* * If there's only one function registered but it does not support - * recursion, this function will be called by the mcount trampoline. - * This function will handle recursion protection. + * recursion, needs RCU protection and/or requires per cpu handling, then + * this function will be called by the mcount trampoline. */ -static void ftrace_ops_recurs_func(unsigned long ip, unsigned long parent_ip, +static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct pt_regs *regs) { int bit; + if ((op->flags & FTRACE_OPS_FL_RCU) && !rcu_is_watching()) + return; + bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX); if (bit < 0) return; - op->func(ip, parent_ip, op, regs); + preempt_disable_notrace(); + if (!(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); } @@ -5261,12 +5270,12 @@ 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 the func handles its own recursion, call it directly. - * Otherwise call the recursion protected function that - * will call the ftrace ops function. + * If the function does not handle recursion, needs to be RCU safe, + * or does per cpu logic, then we need to call the assist handler. */ - if (!(ops->flags & FTRACE_OPS_FL_RECURSION_SAFE)) - return ftrace_ops_recurs_func; + if (!(ops->flags & FTRACE_OPS_FL_RECURSION_SAFE) || + ops->flags & (FTRACE_OPS_FL_RCU | FTRACE_OPS_FL_PER_CPU)) + return ftrace_ops_assist_func; return ops->func; }