tracepoint: check if the probe has been registered

[linux-2.6-omap-h63xx.git] / kernel / trace / trace_sched_switch.c

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 5555b906a6669b2a2c3892626026d8b68b17f87b..b8f56beb1a621d5ff527a93aee383f0e02fd30dd 100644 (file)
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -9,119 +9,157 @@
 #include <linux/debugfs.h>
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>
-#include <linux/marker.h>
 #include <linux/ftrace.h>
+#include <trace/sched.h>
 
 #include "trace.h"
 
 static struct trace_array      *ctx_trace;
 static int __read_mostly       tracer_enabled;
+static atomic_t                        sched_ref;
 
 static void
-ctx_switch_func(void *__rq, struct task_struct *prev, struct task_struct *next)
+probe_sched_switch(struct rq *__rq, struct task_struct *prev,
+                       struct task_struct *next)
 {
-       struct trace_array *tr = ctx_trace;
        struct trace_array_cpu *data;
        unsigned long flags;
-       long disabled;
        int cpu;
+       int pc;
+
+       if (!atomic_read(&sched_ref))
+               return;
+
+       tracing_record_cmdline(prev);
+       tracing_record_cmdline(next);
 
        if (!tracer_enabled)
                return;
 
+       pc = preempt_count();
        local_irq_save(flags);
        cpu = raw_smp_processor_id();
-       data = tr->data[cpu];
-       disabled = atomic_inc_return(&data->disabled);
+       data = ctx_trace->data[cpu];
 
-       if (likely(disabled == 1)) {
-               tracing_sched_switch_trace(tr, data, prev, next, flags);
-               if (trace_flags & TRACE_ITER_SCHED_TREE)
-                       ftrace_all_fair_tasks(__rq, tr, data);
-       }
+       if (likely(!atomic_read(&data->disabled)))
+               tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
 
-       atomic_dec(&data->disabled);
        local_irq_restore(flags);
 }
 
 static void
-wakeup_func(void *__rq, struct task_struct *wakee, struct task_struct *curr)
+probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
 {
-       struct trace_array *tr = ctx_trace;
        struct trace_array_cpu *data;
        unsigned long flags;
-       long disabled;
-       int cpu;
+       int cpu, pc;
 
-       if (!tracer_enabled)
+       if (!likely(tracer_enabled))
                return;
 
+       pc = preempt_count();
+       tracing_record_cmdline(current);
+
        local_irq_save(flags);
        cpu = raw_smp_processor_id();
-       data = tr->data[cpu];
-       disabled = atomic_inc_return(&data->disabled);
+       data = ctx_trace->data[cpu];
 
-       if (likely(disabled == 1)) {
-               tracing_sched_wakeup_trace(tr, data, wakee, curr, flags);
-               if (trace_flags & TRACE_ITER_SCHED_TREE)
-                       ftrace_all_fair_tasks(__rq, tr, data);
-       }
+       if (likely(!atomic_read(&data->disabled)))
+               tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
+                                          flags, pc);
 
-       atomic_dec(&data->disabled);
        local_irq_restore(flags);
 }
 
-void
-ftrace_ctx_switch(void *__rq, struct task_struct *prev,
-                 struct task_struct *next)
+static void sched_switch_reset(struct trace_array *tr)
 {
-       tracing_record_cmdline(prev);
+       int cpu;
 
-       /*
-        * If tracer_switch_func only points to the local
-        * switch func, it still needs the ptr passed to it.
-        */
-       ctx_switch_func(__rq, prev, next);
+       tr->time_start = ftrace_now(tr->cpu);
 
-       /*
-        * Chain to the wakeup tracer (this is a NOP if disabled):
-        */
-       wakeup_sched_switch(prev, next);
+       for_each_online_cpu(cpu)
+               tracing_reset(tr, cpu);
 }
 
-void
-ftrace_wake_up_task(void *__rq, struct task_struct *wakee,
-                   struct task_struct *curr)
+static int tracing_sched_register(void)
 {
-       tracing_record_cmdline(curr);
+       int ret;
 
-       wakeup_func(__rq, wakee, curr);
+       ret = register_trace_sched_wakeup(probe_sched_wakeup);
+       if (ret) {
+               pr_info("wakeup trace: Couldn't activate tracepoint"
+                       " probe to kernel_sched_wakeup\n");
+               return ret;
+       }
+
+       ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
+       if (ret) {
+               pr_info("wakeup trace: Couldn't activate tracepoint"
+                       " probe to kernel_sched_wakeup_new\n");
+               goto fail_deprobe;
+       }
+
+       ret = register_trace_sched_switch(probe_sched_switch);
+       if (ret) {
+               pr_info("sched trace: Couldn't activate tracepoint"
+                       " probe to kernel_sched_schedule\n");
+               goto fail_deprobe_wake_new;
+       }
 
-       /*
-        * Chain to the wakeup tracer (this is a NOP if disabled):
-        */
-       wakeup_sched_wakeup(wakee, curr);
+       return ret;
+fail_deprobe_wake_new:
+       unregister_trace_sched_wakeup_new(probe_sched_wakeup);
+fail_deprobe:
+       unregister_trace_sched_wakeup(probe_sched_wakeup);
+       return ret;
 }
 
-static void sched_switch_reset(struct trace_array *tr)
+static void tracing_sched_unregister(void)
 {
-       int cpu;
+       unregister_trace_sched_switch(probe_sched_switch);
+       unregister_trace_sched_wakeup_new(probe_sched_wakeup);
+       unregister_trace_sched_wakeup(probe_sched_wakeup);
+}
 
-       tr->time_start = ftrace_now(tr->cpu);
+static void tracing_start_sched_switch(void)
+{
+       long ref;
 
-       for_each_online_cpu(cpu)
-               tracing_reset(tr->data[cpu]);
+       ref = atomic_inc_return(&sched_ref);
+       if (ref == 1)
+               tracing_sched_register();
+}
+
+static void tracing_stop_sched_switch(void)
+{
+       long ref;
+
+       ref = atomic_dec_and_test(&sched_ref);
+       if (ref)
+               tracing_sched_unregister();
+}
+
+void tracing_start_cmdline_record(void)
+{
+       tracing_start_sched_switch();
+}
+
+void tracing_stop_cmdline_record(void)
+{
+       tracing_stop_sched_switch();
 }
 
 static void start_sched_trace(struct trace_array *tr)
 {
        sched_switch_reset(tr);
+       tracing_start_cmdline_record();
        tracer_enabled = 1;
 }
 
 static void stop_sched_trace(struct trace_array *tr)
 {
        tracer_enabled = 0;
+       tracing_stop_cmdline_record();
 }
 
 static void sched_switch_trace_init(struct trace_array *tr)
@@ -160,6 +198,14 @@ static struct tracer sched_switch_trace __read_mostly =
 
 __init static int init_sched_switch_trace(void)
 {
+       int ret = 0;
+
+       if (atomic_read(&sched_ref))
+               ret = tracing_sched_register();
+       if (ret) {
+               pr_info("error registering scheduler trace\n");
+               return ret;
+       }
        return register_tracer(&sched_switch_trace);
 }
 device_initcall(init_sched_switch_trace);