tracing: Simplify test for function_graph tracing start point
In the function graph tracer, a calling function is to be traced
only when it is enabled through the set_graph_function file,
or when it is nested in an enabled function.
Current code uses TSK_TRACE_FL_GRAPH to test whether it is nested
or not. Looking at the code, we can get this:
(trace->depth > 0) <==> (TSK_TRACE_FL_GRAPH is set)
trace->depth is more explicit to tell that it is nested.
So we use trace->depth directly and simplify the code.
No functionality is changed.
TSK_TRACE_FL_GRAPH is not removed yet, it is left for future usage.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4B4DB0B6.7040607@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index f225229..616b135 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -215,7 +215,8 @@
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);
@@ -228,9 +229,6 @@
} 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);
@@ -278,8 +276,6 @@
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);
}