From b5130b1e7d3717d03ab1916b198bf0d49fa0a619 Mon Sep 17 00:00:00 2001 From: Carsten Emde 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 Signed-off-by: Steven Rostedt --- 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 45c3f03..ef82a7f 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 28247ce..4ad4e1d 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 06f8ea9..3aa7eaa 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 6e1529b..26185d7 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); -- 2.7.4