tracing: Graph support for wakeup tracer

Add function graph support for wakeup latency tracer.
The graph output is enabled by setting the 'display-graph'
trace option.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <1285243253-7372-4-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 221 insertions, 10 deletions

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 4086eae6e81b..033510dbb322 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -31,13 +31,33 @@ static int			wakeup_rt;
 static arch_spinlock_t wakeup_lock =
         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
+static void wakeup_reset(struct trace_array *tr);
 static void __wakeup_reset(struct trace_array *tr);
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
+static void wakeup_graph_return(struct ftrace_graph_ret *trace);
 
 static int save_lat_flag;
 
+#define TRACE_DISPLAY_GRAPH     1
+
+static struct tracer_opt trace_opts[] = {
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        /* display latency trace as call graph */
+        { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
+#endif
+        { } /* Empty entry */
+};
+
+static struct tracer_flags tracer_flags = {
+        .val  = 0,
+        .opts = trace_opts,
+};
+
+#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
+
 #ifdef CONFIG_FUNCTION_TRACER
 /*
- * irqsoff uses its own tracer function to keep the overhead down:
+ * wakeup uses its own tracer function to keep the overhead down:
  */
 static void
 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
@@ -80,8 +100,191 @@ static struct ftrace_ops trace_ops __read_mostly =
 {
         .func = wakeup_tracer_call,
 };
+
+static int start_func_tracer(int graph)
+{
+        int ret;
+
+        if (!graph)
+                ret = register_ftrace_function(&trace_ops);
+        else
+                ret = register_ftrace_graph(&wakeup_graph_return,
+                                            &wakeup_graph_entry);
+
+        if (!ret && tracing_is_enabled())
+                tracer_enabled = 1;
+        else
+                tracer_enabled = 0;
+
+        return ret;
+}
+
+static void stop_func_tracer(int graph)
+{
+        tracer_enabled = 0;
+
+        if (!graph)
+                unregister_ftrace_function(&trace_ops);
+        else
+                unregister_ftrace_graph();
+}
+
 #endif /* CONFIG_FUNCTION_TRACER */
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
+{
+
+        if (!(bit & TRACE_DISPLAY_GRAPH))
+                return -EINVAL;
+
+        if (!(is_graph() ^ set))
+                return 0;
+
+        stop_func_tracer(!set);
+
+        wakeup_reset(wakeup_trace);
+        tracing_max_latency = 0;
+
+        return start_func_tracer(set);
+}
+
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
+{
+        struct trace_array *tr = wakeup_trace;
+        struct trace_array_cpu *data;
+        unsigned long flags;
+        long disabled;
+        int cpu, pc, ret = 0;
+
+        if (likely(!wakeup_task))
+                return 0;
+
+        pc = preempt_count();
+        preempt_disable_notrace();
+
+        cpu = raw_smp_processor_id();
+        if (cpu != wakeup_current_cpu)
+                goto out_enable;
+
+        data = tr->data[cpu];
+        disabled = atomic_inc_return(&data->disabled);
+        if (unlikely(disabled != 1))
+                goto out;
+
+        local_save_flags(flags);
+        ret = __trace_graph_entry(tr, trace, flags, pc);
+
+out:
+        atomic_dec(&data->disabled);
+
+out_enable:
+        preempt_enable_notrace();
+        return ret;
+}
+
+static void wakeup_graph_return(struct ftrace_graph_ret *trace)
+{
+        struct trace_array *tr = wakeup_trace;
+        struct trace_array_cpu *data;
+        unsigned long flags;
+        long disabled;
+        int cpu, pc;
+
+        if (likely(!wakeup_task))
+                return;
+
+        pc = preempt_count();
+        preempt_disable_notrace();
+
+        cpu = raw_smp_processor_id();
+        if (cpu != wakeup_current_cpu)
+                goto out_enable;
+
+        data = tr->data[cpu];
+        disabled = atomic_inc_return(&data->disabled);
+        if (unlikely(disabled != 1))
+                goto out;
+
+        local_save_flags(flags);
+        __trace_graph_return(tr, trace, flags, pc);
+
+out:
+        atomic_dec(&data->disabled);
+
+out_enable:
+        preempt_enable_notrace();
+        return;
+}
+
+static void wakeup_trace_open(struct trace_iterator *iter)
+{
+        if (is_graph())
+                graph_trace_open(iter);
+}
+
+static void wakeup_trace_close(struct trace_iterator *iter)
+{
+        if (iter->private)
+                graph_trace_close(iter);
+}
+
+#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC)
+
+static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
+{
+        /*
+         * In graph mode call the graph tracer output function,
+         * otherwise go with the TRACE_FN event handler
+         */
+        if (is_graph())
+                return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
+
+        return TRACE_TYPE_UNHANDLED;
+}
+
+static void wakeup_print_header(struct seq_file *s)
+{
+        if (is_graph())
+                print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
+        else
+                trace_default_header(s);
+}
+
+static void
+__trace_function(struct trace_array *tr,
+                 unsigned long ip, unsigned long parent_ip,
+                 unsigned long flags, int pc)
+{
+        if (is_graph())
+                trace_graph_function(tr, ip, parent_ip, flags, pc);
+        else
+                trace_function(tr, ip, parent_ip, flags, pc);
+}
+#else
+#define __trace_function trace_function
+
+static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
+{
+        return -EINVAL;
+}
+
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
+{
+        return -1;
+}
+
+static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
+{
+        return TRACE_TYPE_UNHANDLED;
+}
+
+static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
+static void wakeup_print_header(struct seq_file *s) { }
+static void wakeup_trace_open(struct trace_iterator *iter) { }
+static void wakeup_trace_close(struct trace_iterator *iter) { }
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 /*
  * Should this new latency be reported/recorded?
  */
@@ -152,7 +355,7 @@ probe_wakeup_sched_switch(void *ignore,
         /* The task we are waiting for is waking up */
         data = wakeup_trace->data[wakeup_cpu];
 
-        trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
+        __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 
         T0 = data->preempt_timestamp;
@@ -252,7 +455,7 @@ probe_wakeup(void *ignore, struct task_struct *p, int success)
          * is not called by an assembly function  (where as schedule is)
          * it should be safe to use it here.
          */
-        trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+        __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 
 out_locked:
         arch_spin_unlock(&wakeup_lock);
@@ -303,12 +506,8 @@ static void start_wakeup_tracer(struct trace_array *tr)
          */
         smp_wmb();
 
-        register_ftrace_function(&trace_ops);
-
-        if (tracing_is_enabled())
-                tracer_enabled = 1;
-        else
-                tracer_enabled = 0;
+        if (start_func_tracer(is_graph()))
+                printk(KERN_ERR "failed to start wakeup tracer\n");
 
         return;
 fail_deprobe_wake_new:
@@ -320,7 +519,7 @@ fail_deprobe:
 static void stop_wakeup_tracer(struct trace_array *tr)
 {
         tracer_enabled = 0;
-        unregister_ftrace_function(&trace_ops);
+        stop_func_tracer(is_graph());
         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
         unregister_trace_sched_wakeup(probe_wakeup, NULL);
@@ -379,9 +578,15 @@ static struct tracer wakeup_tracer __read_mostly =
         .start          = wakeup_tracer_start,
         .stop           = wakeup_tracer_stop,
         .print_max      = 1,
+        .print_header   = wakeup_print_header,
+        .print_line     = wakeup_print_line,
+        .flags          = &tracer_flags,
+        .set_flag       = wakeup_set_flag,
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_wakeup,
 #endif
+        .open           = wakeup_trace_open,
+        .close          = wakeup_trace_close,
         .use_max_tr     = 1,
 };
 
@@ -394,9 +599,15 @@ static struct tracer wakeup_rt_tracer __read_mostly =
         .stop           = wakeup_tracer_stop,
         .wait_pipe      = poll_wait_pipe,
         .print_max      = 1,
+        .print_header   = wakeup_print_header,
+        .print_line     = wakeup_print_line,
+        .flags          = &tracer_flags,
+        .set_flag       = wakeup_set_flag,
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_wakeup,
 #endif
+        .open           = wakeup_trace_open,
+        .close          = wakeup_trace_close,
         .use_max_tr     = 1,
 };