Port ftrace to markers

Porting ftrace to the marker infrastructure.

Don't need to chain to the wakeup tracer from the sched tracer, because markers
support multiple probes connected.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 143 insertions, 28 deletions

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index a3376478fc2c..d25ffa5eaf2b 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -16,11 +16,14 @@
 
 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)
+sched_switch_func(void *private, void *__rq, struct task_struct *prev,
+                        struct task_struct *next)
 {
-        struct trace_array *tr = ctx_trace;
+        struct trace_array **ptr = private;
+        struct trace_array *tr = *ptr;
         struct trace_array_cpu *data;
         unsigned long flags;
         long disabled;
@@ -41,10 +44,40 @@ ctx_switch_func(void *__rq, struct task_struct *prev, struct task_struct *next)
         local_irq_restore(flags);
 }
 
+static notrace void
+sched_switch_callback(void *probe_data, void *call_data,
+                      const char *format, va_list *args)
+{
+        struct task_struct *prev;
+        struct task_struct *next;
+        struct rq *__rq;
+
+        if (!atomic_read(&sched_ref))
+                return;
+
+        /* skip prev_pid %d next_pid %d prev_state %ld */
+        (void)va_arg(*args, int);
+        (void)va_arg(*args, int);
+        (void)va_arg(*args, long);
+        __rq = va_arg(*args, typeof(__rq));
+        prev = va_arg(*args, typeof(prev));
+        next = va_arg(*args, typeof(next));
+
+        tracing_record_cmdline(prev);
+
+        /*
+         * If tracer_switch_func only points to the local
+         * switch func, it still needs the ptr passed to it.
+         */
+        sched_switch_func(probe_data, __rq, prev, next);
+}
+
 static void
-wakeup_func(void *__rq, struct task_struct *wakee, struct task_struct *curr)
+wakeup_func(void *private, void *__rq, struct task_struct *wakee, struct
+                        task_struct *curr)
 {
-        struct trace_array *tr = ctx_trace;
+        struct trace_array **ptr = private;
+        struct trace_array *tr = *ptr;
         struct trace_array_cpu *data;
         unsigned long flags;
         long disabled;
@@ -67,35 +100,29 @@ wakeup_func(void *__rq, struct task_struct *wakee, struct task_struct *curr)
         local_irq_restore(flags);
 }
 
-void
-ftrace_ctx_switch(void *__rq, struct task_struct *prev,
-                  struct task_struct *next)
+static notrace void
+wake_up_callback(void *probe_data, void *call_data,
+                 const char *format, va_list *args)
 {
-        if (unlikely(atomic_read(&trace_record_cmdline_enabled)))
-                tracing_record_cmdline(prev);
+        struct task_struct *curr;
+        struct task_struct *task;
+        struct rq *__rq;
 
-        /*
-         * 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);
+        if (likely(!tracer_enabled))
+                return;
 
-        /*
-         * Chain to the wakeup tracer (this is a NOP if disabled):
-         */
-        wakeup_sched_switch(prev, next);
-}
+        /* Skip pid %d state %ld */
+        (void)va_arg(*args, int);
+        (void)va_arg(*args, long);
+        /* now get the meat: "rq %p task %p rq->curr %p" */
+        __rq = va_arg(*args, typeof(__rq));
+        task = va_arg(*args, typeof(task));
+        curr = va_arg(*args, typeof(curr));
 
-void
-ftrace_wake_up_task(void *__rq, struct task_struct *wakee,
-                    struct task_struct *curr)
-{
-        wakeup_func(__rq, wakee, curr);
+        tracing_record_cmdline(task);
+        tracing_record_cmdline(curr);
 
-        /*
-         * Chain to the wakeup tracer (this is a NOP if disabled):
-         */
-        wakeup_sched_wakeup(wakee, curr);
+        wakeup_func(probe_data, __rq, task, curr);
 }
 
 void
@@ -132,15 +159,95 @@ static void sched_switch_reset(struct trace_array *tr)
                 tracing_reset(tr->data[cpu]);
 }
 
+static int tracing_sched_register(void)
+{
+        int ret;
+
+        ret = marker_probe_register("kernel_sched_wakeup",
+                        "pid %d state %ld ## rq %p task %p rq->curr %p",
+                        wake_up_callback,
+                        &ctx_trace);
+        if (ret) {
+                pr_info("wakeup trace: Couldn't add marker"
+                        " probe to kernel_sched_wakeup\n");
+                return ret;
+        }
+
+        ret = marker_probe_register("kernel_sched_wakeup_new",
+                        "pid %d state %ld ## rq %p task %p rq->curr %p",
+                        wake_up_callback,
+                        &ctx_trace);
+        if (ret) {
+                pr_info("wakeup trace: Couldn't add marker"
+                        " probe to kernel_sched_wakeup_new\n");
+                goto fail_deprobe;
+        }
+
+        ret = marker_probe_register("kernel_sched_schedule",
+                "prev_pid %d next_pid %d prev_state %ld "
+                "## rq %p prev %p next %p",
+                sched_switch_callback,
+                &ctx_trace);
+        if (ret) {
+                pr_info("sched trace: Couldn't add marker"
+                        " probe to kernel_sched_schedule\n");
+                goto fail_deprobe_wake_new;
+        }
+
+        return ret;
+fail_deprobe_wake_new:
+        marker_probe_unregister("kernel_sched_wakeup_new",
+                                wake_up_callback,
+                                &ctx_trace);
+fail_deprobe:
+        marker_probe_unregister("kernel_sched_wakeup",
+                                wake_up_callback,
+                                &ctx_trace);
+        return ret;
+}
+
+static void tracing_sched_unregister(void)
+{
+        marker_probe_unregister("kernel_sched_schedule",
+                                sched_switch_callback,
+                                &ctx_trace);
+        marker_probe_unregister("kernel_sched_wakeup_new",
+                                wake_up_callback,
+                                &ctx_trace);
+        marker_probe_unregister("kernel_sched_wakeup",
+                                wake_up_callback,
+                                &ctx_trace);
+}
+
+void tracing_start_sched_switch(void)
+{
+        long ref;
+
+        ref = atomic_inc_return(&sched_ref);
+        if (ref == 1)
+                tracing_sched_register();
+}
+
+void tracing_stop_sched_switch(void)
+{
+        long ref;
+
+        ref = atomic_dec_and_test(&sched_ref);
+        if (ref)
+                tracing_sched_unregister();
+}
+
 static void start_sched_trace(struct trace_array *tr)
 {
         sched_switch_reset(tr);
         atomic_inc(&trace_record_cmdline_enabled);
         tracer_enabled = 1;
+        tracing_start_sched_switch();
 }
 
 static void stop_sched_trace(struct trace_array *tr)
 {
+        tracing_stop_sched_switch();
         atomic_dec(&trace_record_cmdline_enabled);
         tracer_enabled = 0;
 }
@@ -181,6 +288,14 @@ 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);