From b5130b1e7d3717d03ab1916b198bf0d49fa0a619 Mon Sep 17 00:00:00 2001
From: Carsten Emde <Carsten.Emde@osadl.org>
Date: Sun, 13 Sep 2009 01:43:07 +0200
Subject: [PATCH] tracing: do not update tracing_max_latency when tracer is
stopped
The state of the function pair tracing_stop()/tracing_start() is
correctly considered when tracer data are updated. However, the global
and externally accessible variable tracing_max_latency is always updated
- even when tracing is stopped.
The update should only occur, if tracing was not stopped.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 5 +++++
kernel/trace/trace.h | 1 +
kernel/trace/trace_irqsoff.c | 6 ++++--
kernel/trace/trace_sched_wakeup.c | 6 ++++--
4 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 45c3f0352d78..ef82a7fabf3b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -825,6 +825,11 @@ static void trace_init_cmdlines(void)
cmdline_idx = 0;
}
+int is_tracing_stopped(void)
+{
+ return trace_stop_count;
+}
+
/**
* ftrace_off_permanent - disable all ftrace code permanently
*
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 28247cecd955..4ad4e1ddcb9b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -461,6 +461,7 @@ void tracing_stop_sched_switch_record(void);
void tracing_start_sched_switch_record(void);
int register_tracer(struct tracer *type);
void unregister_tracer(struct tracer *type);
+int is_tracing_stopped(void);
extern unsigned long nsecs_to_usecs(unsigned long nsecs);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 06f8ea9e4b9d..3aa7eaa2114c 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -157,8 +157,10 @@ check_critical_timing(struct trace_array *tr,
data->critical_end = parent_ip;
- tracing_max_latency = delta;
- update_max_tr_single(tr, current, cpu);
+ if (likely(!is_tracing_stopped())) {
+ tracing_max_latency = delta;
+ update_max_tr_single(tr, current, cpu);
+ }
max_sequence++;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 6e1529bc6172..26185d727676 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -162,8 +162,10 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
if (!report_latency(delta))
goto out_unlock;
- tracing_max_latency = delta;
- update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
+ if (likely(!is_tracing_stopped())) {
+ tracing_max_latency = delta;
+ update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
+ }
out_unlock:
__wakeup_reset(wakeup_trace);
--
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