From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751451AbcFXKzU (ORCPT ); Fri, 24 Jun 2016 06:55:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52183 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751142AbcFXKzQ (ORCPT ); Fri, 24 Jun 2016 06:55:16 -0400 From: Chunyu Hu To: rostedt@goodmis.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH V3] tracing: Make latency tracers fully support the set_graph_notrace Date: Fri, 24 Jun 2016 18:55:12 +0800 Message-Id: <1466765712-10544-1-git-send-email-chuhu@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 24 Jun 2016 10:55:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org latency tracers(wakeup, wakeup_rt, wakeup_dl, irqsoff) can use the function_graph trace when display_graph trace option is set by user via tracefs. And currently the set_graph_notrace filter is not fully supported in latency tracers, only the graph_ret event can be filtered, the graph_ent events will always be submitted to the trace ring buffer without respecting to the filter. The issue is that the submitted graph_entry event that matches the filter can be assigned with a negative depth(minuts FTRACE_NOTRACE_DEPTH) which will be used as the array index of fgraph_cpu_data when printing trace entries, as a result, an oops can be hit when accessing the array. Fully supporting the set_graph_notrace filter in latency tracers can avoid this oops and provide a small enhancement for these tracers at the same time. To reproduce the oops: echo 1 > options/display_graph echo schedule > set_graph_notrace echo wakeup > current_tracer cat trace (several times) Signed-off-by: Chunyu Hu --- kernel/trace/trace_irqsoff.c | 6 ++++++ kernel/trace/trace_sched_wakeup.c | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index 03cdff8..a4ed46a 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -175,6 +175,12 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent *trace) int ret; int pc; + if (trace->depth < 0) + return 0; + + if (ftrace_graph_notrace_addr(trace->func)) + return 1; + if (!func_prolog_dec(tr, &data, &flags)) return 0; diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 9d4399b..e54fff7 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -239,6 +239,12 @@ static int wakeup_graph_entry(struct ftrace_graph_ent *trace) unsigned long flags; int pc, ret = 0; + if (trace->depth < 0) + return 0; + + if (ftrace_graph_notrace_addr(trace->func)) + return 1; + if (!func_prolog_preempt_disable(tr, &data, &pc)) return 0; -- 1.8.3.1