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, 100 insertions, 6 deletions

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 5948011006bc..5d2fb48e47f8 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -15,6 +15,7 @@
 #include <linux/kallsyms.h>
 #include <linux/uaccess.h>
 #include <linux/ftrace.h>
+#include <linux/marker.h>
 
 #include "trace.h"
 
@@ -44,11 +45,13 @@ static int report_latency(cycle_t delta)
         return 1;
 }
 
-void
-wakeup_sched_switch(struct task_struct *prev, struct task_struct *next)
+static void notrace
+wakeup_sched_switch(void *private, void *rq, struct task_struct *prev,
+        struct task_struct *next)
 {
         unsigned long latency = 0, t0 = 0, t1 = 0;
-        struct trace_array *tr = wakeup_trace;
+        struct trace_array **ptr = private;
+        struct trace_array *tr = *ptr;
         struct trace_array_cpu *data;
         cycle_t T0, T1, delta;
         unsigned long flags;
@@ -113,6 +116,31 @@ out:
         atomic_dec(&tr->data[cpu]->disabled);
 }
 
+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;
+
+        /* 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.
+         */
+        wakeup_sched_switch(probe_data, __rq, prev, next);
+}
+
 static void __wakeup_reset(struct trace_array *tr)
 {
         struct trace_array_cpu *data;
@@ -188,19 +216,68 @@ out:
         atomic_dec(&tr->data[cpu]->disabled);
 }
 
-void wakeup_sched_wakeup(struct task_struct *wakee, struct task_struct *curr)
+static notrace void
+wake_up_callback(void *probe_data, void *call_data,
+                 const char *format, va_list *args)
 {
+        struct trace_array **ptr = probe_data;
+        struct trace_array *tr = *ptr;
+        struct task_struct *curr;
+        struct task_struct *task;
+        struct rq *__rq;
+
         if (likely(!tracer_enabled))
                 return;
 
+        /* 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));
+
+        tracing_record_cmdline(task);
         tracing_record_cmdline(curr);
-        tracing_record_cmdline(wakee);
 
-        wakeup_check_start(wakeup_trace, wakee, curr);
+        wakeup_check_start(tr, task, curr);
 }
 
 static void start_wakeup_tracer(struct trace_array *tr)
 {
+        int ret;
+
+        ret = marker_probe_register("kernel_sched_wakeup",
+                        "pid %d state %ld ## rq %p task %p rq->curr %p",
+                        wake_up_callback,
+                        &wakeup_trace);
+        if (ret) {
+                pr_info("wakeup trace: Couldn't add marker"
+                        " probe to kernel_sched_wakeup\n");
+                return;
+        }
+
+        ret = marker_probe_register("kernel_sched_wakeup_new",
+                        "pid %d state %ld ## rq %p task %p rq->curr %p",
+                        wake_up_callback,
+                        &wakeup_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,
+                &wakeup_trace);
+        if (ret) {
+                pr_info("sched trace: Couldn't add marker"
+                        " probe to kernel_sched_schedule\n");
+                goto fail_deprobe_wake_new;
+        }
+
         wakeup_reset(tr);
 
         /*
@@ -215,11 +292,28 @@ static void start_wakeup_tracer(struct trace_array *tr)
         tracer_enabled = 1;
 
         return;
+fail_deprobe_wake_new:
+        marker_probe_unregister("kernel_sched_wakeup_new",
+                                wake_up_callback,
+                                &wakeup_trace);
+fail_deprobe:
+        marker_probe_unregister("kernel_sched_wakeup",
+                                wake_up_callback,
+                                &wakeup_trace);
 }
 
 static void stop_wakeup_tracer(struct trace_array *tr)
 {
         tracer_enabled = 0;
+        marker_probe_unregister("kernel_sched_schedule",
+                                sched_switch_callback,
+                                &wakeup_trace);
+        marker_probe_unregister("kernel_sched_wakeup_new",
+                                wake_up_callback,
+                                &wakeup_trace);
+        marker_probe_unregister("kernel_sched_wakeup",
+                                wake_up_callback,
+                                &wakeup_trace);
 }
 
 static void wakeup_tracer_init(struct trace_array *tr)