[PATCH tip 1/1] tracing: Use a single trace_enabled variable

Arnaldo Carvalho de Melo
2009-02-09T21:15:58Z

Impact: API change/cleanup

$ codiff kernel/trace/built-in.o.before kernel/trace/built-in.o
kernel/trace/trace.c:
tracing_is_enabled | -12
__find_next_entry | -5
2 functions changed, 17 bytes removed, diff: -17

kernel/trace/trace_sched_switch.c:
tracing_sched_switch_assign_trace | -13
tracing_stop_sched_switch_record | -74
tracing_start_sched_switch_record | -30
3 functions changed, 117 bytes removed, diff: -117

kernel/trace/trace_sysprof.c:
stack_trace_reset | -10
stack_trace_init | -10
2 functions changed, 20 bytes removed, diff: -20

kernel/trace/trace_irqsoff.c:
irqsoff_tracer_start | -16
irqsoff_tracer_stop | -16
irqsoff_tracer_reset | -10
irqsoff_tracer_init | -19
4 functions changed, 61 bytes removed, diff: -61

kernel/trace/trace_sched_wakeup.c:
wakeup_tracer_stop | -16
wakeup_tracer_start | -10
start_wakeup_tracer | -19
wakeup_tracer_reset | -10
4 functions changed, 55 bytes removed, diff: -55

kernel/trace/built-in.o:
15 functions changed, 270 bytes removed, diff: -270

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
kernel/trace/trace.c | 15 +-------------
kernel/trace/trace.h | 3 +-
kernel/trace/trace_irqsoff.c | 22 --------------------
kernel/trace/trace_sched_switch.c | 40 +------------------------------------
kernel/trace/trace_sched_wakeup.c | 26 ------------------------
kernel/trace/trace_sysprof.c | 5 +---
6 files changed, 5 insertions(+), 106 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5b1e9a9..37bb6a9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -182,20 +182,7 @@ static struct trace_array max_tr;
static DEFINE_PER_CPU(struct trace_array_cpu, max_data);

/* tracer_enabled is used to toggle activation of a tracer */
-static int tracer_enabled = 1;
-
-/**
- * tracing_is_enabled - return tracer_enabled status
- *
- * This function is used by other tracers to know the status
- * of the tracer_enabled flag. Tracers may use this function
- * to know if it should enable their features when starting
- * up. See irqsoff tracer for an example (start_irqsoff_tracer).
- */
-int tracing_is_enabled(void)
-{
- return tracer_enabled;
-}
+int tracer_enabled __read_mostly;

/*
* trace_buf_size is the size in bytes that is allocated
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7b0518a..faa4791 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -396,8 +396,9 @@ struct trace_iterator {
cpumask_var_t started;
};

+extern int tracer_enabled;
+
int tracer_init(struct tracer *t, struct trace_array *tr);
-int tracing_is_enabled(void);
void trace_wake_up(void);
void tracing_reset(struct trace_array *tr, int cpu);
void tracing_reset_online_cpus(struct trace_array *tr);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index c6b442d..42364e8 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -19,7 +19,6 @@
#include "trace.h"

static struct trace_array *irqsoff_trace __read_mostly;
-static int tracer_enabled __read_mostly;

static DEFINE_PER_CPU(int, tracing_cpu);

@@ -356,15 +355,10 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
static void start_irqsoff_tracer(struct trace_array *tr)
{
register_ftrace_function(&trace_ops);
- if (tracing_is_enabled())
- tracer_enabled = 1;
- else
- tracer_enabled = 0;
}

static void stop_irqsoff_tracer(struct trace_array *tr)
{
- tracer_enabled = 0;
unregister_ftrace_function(&trace_ops);
}

@@ -382,16 +376,6 @@ static void irqsoff_tracer_reset(struct trace_array *tr)
stop_irqsoff_tracer(tr);
}

-static void irqsoff_tracer_start(struct trace_array *tr)
-{
- tracer_enabled = 1;
-}
-
-static void irqsoff_tracer_stop(struct trace_array *tr)
-{
- tracer_enabled = 0;
-}
-
#ifdef CONFIG_IRQSOFF_TRACER
static int irqsoff_tracer_init(struct trace_array *tr)
{
@@ -405,8 +389,6 @@ static struct tracer irqsoff_tracer __read_mostly =
.name = "irqsoff",
.init = irqsoff_tracer_init,
.reset = irqsoff_tracer_reset,
- .start = irqsoff_tracer_start,
- .stop = irqsoff_tracer_stop,
.print_max = 1,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_irqsoff,
@@ -431,8 +413,6 @@ static struct tracer preemptoff_tracer __read_mostly =
.name = "preemptoff",
.init = preemptoff_tracer_init,
.reset = irqsoff_tracer_reset,
- .start = irqsoff_tracer_start,
- .stop = irqsoff_tracer_stop,
.print_max = 1,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_preemptoff,
@@ -459,8 +439,6 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
.name = "preemptirqsoff",
.init = preemptirqsoff_tracer_init,
.reset = irqsoff_tracer_reset,
- .start = irqsoff_tracer_start,
- .stop = irqsoff_tracer_stop,
.print_max = 1,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_preemptirqsoff,
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 30e14fe..828a70b 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -15,7 +15,6 @@
#include "trace.h"

static struct trace_array *ctx_trace;
-static int __read_mostly tracer_enabled;
static int sched_ref;
static DEFINE_MUTEX(sched_register_mutex);

@@ -151,43 +150,6 @@ void tracing_start_sched_switch_record(void)
}

tracing_start_sched_switch();
-
- mutex_lock(&sched_register_mutex);
- tracer_enabled++;
- mutex_unlock(&sched_register_mutex);
-}
-
-/**
- * tracing_stop_sched_switch_record - start tracing context switches
- *
- * Turns off context switch tracing for a tracer.
- */
-void tracing_stop_sched_switch_record(void)
-{
- mutex_lock(&sched_register_mutex);
- tracer_enabled--;
- WARN_ON(tracer_enabled < 0);
- mutex_unlock(&sched_register_mutex);
-
- tracing_stop_sched_switch();
-}
-
-/**
- * tracing_sched_switch_assign_trace - assign a trace array for ctx switch
- * @tr: trace array pointer to assign
- *
- * Some tracers might want to record the context switches in their
- * trace. This function lets those tracers assign the trace array
- * to use.
- */
-void tracing_sched_switch_assign_trace(struct trace_array *tr)
-{
- ctx_trace = tr;
-}
-
-static void stop_sched_trace(struct trace_array *tr)
-{
- tracing_stop_sched_switch_record();
}

static int sched_switch_trace_init(struct trace_array *tr)
@@ -200,7 +162,7 @@ static int sched_switch_trace_init(struct trace_array *tr)
static void sched_switch_trace_reset(struct trace_array *tr)
{
if (sched_ref)
- stop_sched_trace(tr);
+ tracing_stop_sched_switch();
}

static void sched_switch_trace_start(struct trace_array *tr)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 96d7164..c526a1b 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -20,7 +20,6 @@
#include "trace.h"

static struct trace_array *wakeup_trace;
-static int __read_mostly tracer_enabled;

static struct task_struct *wakeup_task;
static int wakeup_cpu;
@@ -289,23 +288,7 @@ static void start_wakeup_tracer(struct trace_array *tr)
}

wakeup_reset(tr);
-
- /*
- * Don't let the tracer_enabled = 1 show up before
- * the wakeup_task is reset. This may be overkill since
- * wakeup_reset does a spin_unlock after setting the
- * wakeup_task to NULL, but I want to be safe.
- * This is a slow path anyway.
- */
- smp_wmb();
-
register_ftrace_function(&trace_ops);
-
- if (tracing_is_enabled())
- tracer_enabled = 1;
- else
- tracer_enabled = 0;
-
return;
fail_deprobe_wake_new:
unregister_trace_sched_wakeup_new(probe_wakeup);
@@ -315,7 +298,6 @@ fail_deprobe:

static void stop_wakeup_tracer(struct trace_array *tr)
{
- tracer_enabled = 0;
unregister_ftrace_function(&trace_ops);
unregister_trace_sched_switch(probe_wakeup_sched_switch);
unregister_trace_sched_wakeup_new(probe_wakeup);
@@ -352,12 +334,6 @@ static void wakeup_tracer_reset(struct trace_array *tr)
static void wakeup_tracer_start(struct trace_array *tr)
{
wakeup_reset(tr);
- tracer_enabled = 1;
-}
-
-static void wakeup_tracer_stop(struct trace_array *tr)
-{
- tracer_enabled = 0;
}

static struct tracer wakeup_tracer __read_mostly =
@@ -366,7 +342,6 @@ static struct tracer wakeup_tracer __read_mostly =
.init = wakeup_tracer_init,
.reset = wakeup_tracer_reset,
.start = wakeup_tracer_start,
- .stop = wakeup_tracer_stop,
.print_max = 1,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
@@ -379,7 +354,6 @@ static struct tracer wakeup_rt_tracer __read_mostly =
.init = wakeup_rt_tracer_init,
.reset = wakeup_tracer_reset,
.start = wakeup_tracer_start,
- .stop = wakeup_tracer_stop,
.print_max = 1,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_wakeup,
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index 84ca9d8..5c986b4 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -18,8 +18,7 @@

#include "trace.h"

-static struct trace_array *sysprof_trace;
-static int __read_mostly tracer_enabled;
+static struct trace_array *sysprof_trace;

/*
* 1 msec sample interval by default:
@@ -230,7 +229,6 @@ static void stop_stack_trace(struct trace_array *tr)
{
mutex_lock(&sample_timer_lock);
stop_stack_timers();
- tracer_enabled = 0;
mutex_unlock(&sample_timer_lock);
}

@@ -240,7 +238,6 @@ static int stack_trace_init(struct trace_array *tr)

mutex_lock(&sample_timer_lock);
start_stack_timers();
- tracer_enabled = 1;
mutex_unlock(&sample_timer_lock);
return 0;
}
--
1.6.0.6