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Diffstat (limited to 'kernel/trace/trace_functions_graph.c')
-rw-r--r--kernel/trace/trace_functions_graph.c68
1 files changed, 65 insertions, 3 deletions
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4edb4b74eb7e..39ada66389cc 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);
@@ -250,8 +258,9 @@ 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);
@@ -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);