1 files changed, 71 insertions, 9 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4edb4b74eb7e..8388bc99f2ee 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -47,6 +47,8 @@ struct fgraph_data {
 #define TRACE_GRAPH_PRINT_ABS_TIME      0x20
 #define TRACE_GRAPH_PRINT_IRQS          0x40
 
+static unsigned int max_depth;
+
 static struct tracer_opt trace_opts[] = {
         /* Display overruns? (for self-debug purpose) */
         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
@@ -189,10 +191,16 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 
         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
         trace.rettime = trace_clock_local();
-        ftrace_graph_return(&trace);
         barrier();
         current->curr_ret_stack--;
 
+        /*
+         * The trace should run after decrementing the ret counter
+         * in case an interrupt were to come in. We don't want to
+         * lose the interrupt if max_depth is set.
+         */
+        ftrace_graph_return(&trace);
+
         if (unlikely(!ret)) {
                 ftrace_graph_stop();
                 WARN_ON(1);
@@ -210,7 +218,7 @@ int __trace_graph_entry(struct trace_array *tr,
 {
         struct ftrace_event_call *call = &event_funcgraph_entry;
         struct ring_buffer_event *event;
-        struct ring_buffer *buffer = tr->buffer;
+        struct ring_buffer *buffer = tr->trace_buffer.buffer;
         struct ftrace_graph_ent_entry *entry;
 
         if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
@@ -250,13 +258,14 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
                 return 0;
 
         /* trace it when it is-nested-in or is a function enabled. */
-        if (!(trace->depth || ftrace_graph_addr(trace->func)) ||
-              ftrace_graph_ignore_irqs())
+        if ((!(trace->depth || ftrace_graph_addr(trace->func)) ||
+             ftrace_graph_ignore_irqs()) ||
+            (max_depth && trace->depth >= max_depth))
                 return 0;
 
         local_irq_save(flags);
         cpu = raw_smp_processor_id();
-        data = tr->data[cpu];
+        data = per_cpu_ptr(tr->trace_buffer.data, cpu);
         disabled = atomic_inc_return(&data->disabled);
         if (likely(disabled == 1)) {
                 pc = preempt_count();
@@ -314,7 +323,7 @@ void __trace_graph_return(struct trace_array *tr,
 {
         struct ftrace_event_call *call = &event_funcgraph_exit;
         struct ring_buffer_event *event;
-        struct ring_buffer *buffer = tr->buffer;
+        struct ring_buffer *buffer = tr->trace_buffer.buffer;
         struct ftrace_graph_ret_entry *entry;
 
         if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
@@ -341,7 +350,7 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
 
         local_irq_save(flags);
         cpu = raw_smp_processor_id();
-        data = tr->data[cpu];
+        data = per_cpu_ptr(tr->trace_buffer.data, cpu);
         disabled = atomic_inc_return(&data->disabled);
         if (likely(disabled == 1)) {
                 pc = preempt_count();
@@ -551,9 +560,9 @@ get_return_for_leaf(struct trace_iterator *iter,
                          * We need to consume the current entry to see
                          * the next one.
                          */
-                        ring_buffer_consume(iter->tr->buffer, iter->cpu,
+                        ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
                                             NULL, NULL);
-                        event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
+                        event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
                                                  NULL, NULL);
                 }
 
@@ -1457,6 +1466,59 @@ static struct tracer graph_trace __read_mostly = {
 #endif
 };
 
+
+static ssize_t
+graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
+                  loff_t *ppos)
+{
+        unsigned long val;
+        int ret;
+
+        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
+        if (ret)
+                return ret;
+
+        max_depth = val;
+
+        *ppos += cnt;
+
+        return cnt;
+}
+
+static ssize_t
+graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
+                 loff_t *ppos)
+{
+        char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
+        int n;
+
+        n = sprintf(buf, "%d\n", max_depth);
+
+        return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
+}
+
+static const struct file_operations graph_depth_fops = {
+        .open           = tracing_open_generic,
+        .write          = graph_depth_write,
+        .read           = graph_depth_read,
+        .llseek         = generic_file_llseek,
+};
+
+static __init int init_graph_debugfs(void)
+{
+        struct dentry *d_tracer;
+
+        d_tracer = tracing_init_dentry();
+        if (!d_tracer)
+                return 0;
+
+        trace_create_file("max_graph_depth", 0644, d_tracer,
+                          NULL, &graph_depth_fops);
+
+        return 0;
+}
+fs_initcall(init_graph_debugfs);
+
 static __init int init_graph_trace(void)
 {
         max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);