From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761686Ab3IDBvz (ORCPT ); Tue, 3 Sep 2013 21:51:55 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:31877 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761538Ab3IDBvy (ORCPT ); Tue, 3 Sep 2013 21:51:54 -0400 X-Authority-Analysis: v=2.0 cv=fJG7LOme c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=6vL9NhcTi7YA:10 a=5SG0PmZfjMsA:10 a=kj9zAlcOel0A:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=Lu4-lkDicUYA:10 a=VnNF1IyMAAAA:8 a=-ErlrlILWjhT9ab7BowA:9 a=CjuIK1q_8ugA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Date: Tue, 3 Sep 2013 21:51:52 -0400 From: Steven Rostedt To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Peter Zijlstra , Frederic Weisbecker , Jiri Olsa Subject: Re: [RFC][PATCH 01/18 v2] ftrace: Add hash list to save RCU unsafe functions Message-ID: <20130903215152.1e91922b@gandalf.local.home> In-Reply-To: <20130904012404.GI3871@linux.vnet.ibm.com> References: <20130831051117.884125230@goodmis.org> <20130831051700.601365837@goodmis.org> <20130903171516.16290c47@gandalf.local.home> <20130903221808.GH3871@linux.vnet.ibm.com> <20130903195705.3ba3442f@gandalf.local.home> <20130904012404.GI3871@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.9.2 (GTK+ 2.24.20; 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, 3 Sep 2013 18:24:04 -0700 "Paul E. McKenney" wrote: > On Tue, Sep 03, 2013 at 07:57:05PM -0400, Steven Rostedt wrote: > > Paul, can I still keep all your acks and reviewed-bys on this? > > Yep, but some questions below. > > Thanx, Paul > > > -- Steve > > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > > index 310b727..899c8c1 100644 > > --- a/kernel/trace/ftrace.c > > +++ b/kernel/trace/ftrace.c > > @@ -1373,7 +1373,7 @@ ftrace_hash_rec_enable(struct ftrace_ops *ops, int filter_hash); > > > > static int ftrace_convert_size_to_bits(int size) > > { > > - int bits; > > + int bits = 0; > > > > /* > > * Make the hash size about 1/2 the # found > > diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c > > index f5a9031..0883069 100644 > > --- a/kernel/trace/trace_functions.c > > +++ b/kernel/trace/trace_functions.c > > @@ -561,16 +561,21 @@ static inline int init_func_cmd_traceon(void) > > > > #ifdef CONFIG_FTRACE_UNSAFE_RCU_CHECKER > > > > +static DEFINE_PER_CPU(int, ftrace_rcu_running); > > static atomic_t ftrace_unsafe_rcu_disabled; > > > > void ftrace_unsafe_rcu_checker_disable(void) > > { > > atomic_inc(&ftrace_unsafe_rcu_disabled); > > + /* Make sure the update is seen immediately */ > > + smp_wmb(); > > smp_mb__after_atomic_inc()? Yep. > > > } > > > > void ftrace_unsafe_rcu_checker_enable(void) > > { > > atomic_dec(&ftrace_unsafe_rcu_disabled); > > + /* Make sure the update is seen immediately */ > > + smp_wmb(); > > smp_mb__after_atomic_dec()? Yep. > > > } > > > > static DEFINE_PER_CPU(unsigned long, ftrace_rcu_func); > > @@ -588,15 +593,14 @@ static void > > ftrace_unsafe_callback(unsigned long ip, unsigned long parent_ip, > > struct ftrace_ops *op, struct pt_regs *pt_regs) > > { > > - int bit; > > - > > + /* Make sure we see disabled or not first */ > > + smp_rmb(); > > smp_mb__before_atomic_inc()? Yep. I'll update it and restart my tests. Thanks! -- Steve > > > if (atomic_read(&ftrace_unsafe_rcu_disabled)) > > return; > > > > preempt_disable_notrace(); > > > > - bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX); > > - if (bit < 0) > > + if (this_cpu_read(ftrace_rcu_running)) > > goto out; > > > > if (WARN_ONCE(ftrace_rcu_unsafe(ip), > > @@ -604,13 +608,15 @@ ftrace_unsafe_callback(unsigned long ip, unsigned long parent_ip, > > (void *)ip)) > > goto out; > > > > + this_cpu_write(ftrace_rcu_running, 1); > > this_cpu_write(ftrace_rcu_func, ip); > > + > > /* Should trigger a RCU splat if called from unsafe RCU function */ > > rcu_read_lock(); > > rcu_read_unlock(); > > this_cpu_write(ftrace_rcu_func, 0); > > > > - trace_clear_recursion(bit); > > + this_cpu_write(ftrace_rcu_running, 0); > > out: > > preempt_enable_notrace(); > > } > >