1 files changed, 54 insertions, 24 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b1342c5d37c..e998a824e9d 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -18,6 +18,7 @@ struct fgraph_cpu_data {
         pid_t           last_pid;
         int             depth;
         int             ignore;
+        unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
 };
 
 struct fgraph_data {
@@ -212,13 +213,11 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
         int cpu;
         int pc;
 
-        if (unlikely(!tr))
-                return 0;
-
         if (!ftrace_trace_task(current))
                 return 0;
 
-        if (!ftrace_graph_addr(trace->func))
+        /* trace it when it is-nested-in or is a function enabled. */
+        if (!(trace->depth || ftrace_graph_addr(trace->func)))
                 return 0;
 
         local_irq_save(flags);
@@ -231,9 +230,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
         } else {
                 ret = 0;
         }
-        /* Only do the atomic if it is not already set */
-        if (!test_tsk_trace_graph(current))
-                set_tsk_trace_graph(current);
 
         atomic_dec(&data->disabled);
         local_irq_restore(flags);
@@ -281,17 +277,24 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
                 pc = preempt_count();
                 __trace_graph_return(tr, trace, flags, pc);
         }
-        if (!trace->depth)
-                clear_tsk_trace_graph(current);
         atomic_dec(&data->disabled);
         local_irq_restore(flags);
 }
 
+void set_graph_array(struct trace_array *tr)
+{
+        graph_array = tr;
+
+        /* Make graph_array visible before we start tracing */
+
+        smp_mb();
+}
+
 static int graph_trace_init(struct trace_array *tr)
 {
         int ret;
 
-        graph_array = tr;
+        set_graph_array(tr);
         ret = register_ftrace_graph(&trace_graph_return,
                                     &trace_graph_entry);
         if (ret)
@@ -301,11 +304,6 @@ static int graph_trace_init(struct trace_array *tr)
         return 0;
 }
 
-void set_graph_array(struct trace_array *tr)
-{
-        graph_array = tr;
-}
-
 static void graph_trace_reset(struct trace_array *tr)
 {
         tracing_stop_cmdline_record();
@@ -673,15 +671,21 @@ print_graph_entry_leaf(struct trace_iterator *iter,
         duration = graph_ret->rettime - graph_ret->calltime;
 
         if (data) {
+                struct fgraph_cpu_data *cpu_data;
                 int cpu = iter->cpu;
-                int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
+
+                cpu_data = per_cpu_ptr(data->cpu_data, cpu);
 
                 /*
                  * Comments display at + 1 to depth. Since
                  * this is a leaf function, keep the comments
                  * equal to this depth.
                  */
-                *depth = call->depth - 1;
+                cpu_data->depth = call->depth - 1;
+
+                /* No need to keep this function around for this depth */
+                if (call->depth < FTRACE_RETFUNC_DEPTH)
+                        cpu_data->enter_funcs[call->depth] = 0;
         }
 
         /* Overhead */
@@ -721,10 +725,15 @@ print_graph_entry_nested(struct trace_iterator *iter,
         int i;
 
         if (data) {
+                struct fgraph_cpu_data *cpu_data;
                 int cpu = iter->cpu;
-                int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
 
-                *depth = call->depth;
+                cpu_data = per_cpu_ptr(data->cpu_data, cpu);
+                cpu_data->depth = call->depth;
+
+                /* Save this function pointer to see if the exit matches */
+                if (call->depth < FTRACE_RETFUNC_DEPTH)
+                        cpu_data->enter_funcs[call->depth] = call->func;
         }
 
         /* No overhead */
@@ -854,19 +863,28 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
         struct fgraph_data *data = iter->private;
         pid_t pid = ent->pid;
         int cpu = iter->cpu;
+        int func_match = 1;
         int ret;
         int i;
 
         if (data) {
+                struct fgraph_cpu_data *cpu_data;
                 int cpu = iter->cpu;
-                int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
+
+                cpu_data = per_cpu_ptr(data->cpu_data, cpu);
 
                 /*
                  * Comments display at + 1 to depth. This is the
                  * return from a function, we now want the comments
                  * to display at the same level of the bracket.
                  */
-                *depth = trace->depth - 1;
+                cpu_data->depth = trace->depth - 1;
+
+                if (trace->depth < FTRACE_RETFUNC_DEPTH) {
+                        if (cpu_data->enter_funcs[trace->depth] != trace->func)
+                                func_match = 0;
+                        cpu_data->enter_funcs[trace->depth] = 0;
+                }
         }
 
         if (print_graph_prologue(iter, s, 0, 0))
@@ -891,9 +909,21 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
                         return TRACE_TYPE_PARTIAL_LINE;
         }
 
-        ret = trace_seq_printf(s, "}\n");
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
+        /*
+         * If the return function does not have a matching entry,
+         * then the entry was lost. Instead of just printing
+         * the '}' and letting the user guess what function this
+         * belongs to, write out the function name.
+         */
+        if (func_match) {
+                ret = trace_seq_printf(s, "}\n");
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        } else {
+                ret = trace_seq_printf(s, "} (%ps)\n", (void *)trace->func);
+                if (!ret)
+                        return TRACE_TYPE_PARTIAL_LINE;
+        }
 
         /* Overrun */
         if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {