From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
In order to make the function graph infrastructure more generic, there can
not be code specific for the function_graph tracer in the generic code. This
includes the set_graph_notrace logic, that stops all graph calls when a
function in the set_graph_notrace is hit.
By using the trace_recursion mask, we can use a bit in the current
task_struct to implement the notrace code, and move the logic out of
fgraph.c and into trace_functions_graph.c and keeps it affecting only the
tracer and not all call graph callbacks.
Cc: Namhyung Kim <namhy...@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
kernel/trace/fgraph.c | 21 ---------------------
kernel/trace/trace.h | 6 ++++++
kernel/trace/trace_functions_graph.c | 21 +++++++++++++++++++++
3 files changed, 27 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index e8fcf1b2b38c..c684968b87e7 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -64,30 +64,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long
func,
return -EBUSY;
}
- /*
- * The curr_ret_stack is an index to ftrace return stack of
- * current task. Its value should be in [0, FTRACE_RETFUNC_
- * DEPTH) when the function graph tracer is used. To support
- * filtering out specific functions, it makes the index
- * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
- * so when it sees a negative index the ftrace will ignore
- * the record. And the index gets recovered when returning
- * from the filtered function by adding the FTRACE_NOTRACE_
- * DEPTH and then it'll continue to record functions normally.
- *
- * The curr_ret_stack is initialized to -1 and get increased
- * in this function. So it can be less than -1 only if it was
- * filtered out via ftrace_graph_notrace_addr() which can be
- * set from set_graph_notrace file in tracefs by user.
- */
- if (current->curr_ret_stack < -1)
- return -EBUSY;
-
calltime = trace_clock_local();
index = ++current->curr_ret_stack;
- if (ftrace_graph_notrace_addr(func))
- current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
barrier();
current->ret_stack[index].ret = ret;
current->ret_stack[index].func = func;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3b8c0e24ab30..f3ad85830961 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -512,6 +512,12 @@ enum {
* can only be modified by current, we can reuse trace_recursion.
*/
TRACE_IRQ_BIT,
+/*
+ * To implement set_graph_notrace, if this bit is set, we ignore
+ * function graph tracing of called functions, until the return
+ * function is called to clear it.
+ */
+ TRACE_GRAPH_NOTRACE_BIT,
};
#define trace_recursion_set(bit) do { (current)->trace_recursion |=
(1<<(bit)); } while (0)
diff --git a/kernel/trace/trace_functions_graph.c
b/kernel/trace/trace_functions_graph.c
index af1759cd6eab..4748dc1bf5e1 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -188,6 +188,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
int cpu;
int pc;
+ if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
+ return 0;
+
+ if (ftrace_graph_notrace_addr(trace->func)) {
+ trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
+ /*
+ * Need to return 1 to have the return called
+ * that will clear the NOTRACE bit.
+ */
+ return 1;
+ }
+
if (!ftrace_trace_task(tr))
return 0;
@@ -288,6 +300,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
int cpu;
int pc;
+ if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
+ trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+ return;
+ }
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -311,6 +328,10 @@ void set_graph_array(struct trace_array *tr)
static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
+ if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
+ trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+ return;
+ }
if (tracing_thresh &&
(trace->rettime - trace->calltime < tracing_thresh))
return;
--
2.19.1
