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

Frederic Weisbecker
2009-02-09T23:49:34Z

On Mon, Feb 09, 2009 at 07:15:35PM -0200, Arnaldo Carvalho de Melo wrote:
> 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
>

That looks good :-)

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>