ftrace: fix updates to max trace
This patch fixes some bugs to the updating of the max trace that
was caused by implementing the new buffering.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index bd3f881..74165f6 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -23,6 +23,8 @@
static DEFINE_PER_CPU(int, tracing_cpu);
+static DEFINE_SPINLOCK(max_trace_lock);
+
enum {
TRACER_IRQS_OFF = (1 << 1),
TRACER_PREEMPT_OFF = (1 << 2),
@@ -126,7 +128,7 @@
int cpu)
{
unsigned long latency, t0, t1;
- cycle_t T0, T1, T2, delta;
+ cycle_t T0, T1, delta;
unsigned long flags;
/*
@@ -142,20 +144,18 @@
if (!report_latency(delta))
goto out;
- ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);
- /*
- * Update the timestamp, because the trace entry above
- * might change it (it can only get larger so the latency
- * is fair to be reported):
- */
- T2 = now(cpu);
+ spin_lock(&max_trace_lock);
- delta = T2-T0;
+ /* check if we are still the max latency */
+ if (!report_latency(delta))
+ goto out_unlock;
+
+ ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);
latency = nsecs_to_usecs(delta);
if (data->critical_sequence != max_sequence)
- goto out;
+ goto out_unlock;
tracing_max_latency = delta;
t0 = nsecs_to_usecs(T0);
@@ -189,6 +189,9 @@
max_sequence++;
+out_unlock:
+ spin_unlock(&max_trace_lock);
+
out:
data->critical_sequence = max_sequence;
data->preempt_timestamp = now(cpu);
@@ -366,14 +369,14 @@
static void start_irqsoff_tracer(struct trace_array *tr)
{
- tracer_enabled = 1;
register_ftrace_function(&trace_ops);
+ tracer_enabled = 1;
}
static void stop_irqsoff_tracer(struct trace_array *tr)
{
- unregister_ftrace_function(&trace_ops);
tracer_enabled = 0;
+ unregister_ftrace_function(&trace_ops);
}
static void __irqsoff_tracer_init(struct trace_array *tr)