---

yaml
---
r: 121054
b: refs/heads/master
c: b2a866f
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 182e9f5f704ed6b9175142fe8da33c9ce0c52b52
+refs/heads/master: b2a866f9344cb30d7ddf5d67b5b8393daf8bef07

trunk/kernel/trace/trace.c

@@ -244,6 +244,7 @@ static const char *trace_options[] = {
 	"stacktrace",
 	"sched-tree",
 	"ftrace_printk",
+	"ftrace_preempt",
 	NULL
 };
 
@@ -891,7 +892,7 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
 
 #ifdef CONFIG_FUNCTION_TRACER
 static void
-function_trace_call(unsigned long ip, unsigned long parent_ip)
+function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
 {
 	struct trace_array *tr = &global_trace;
 	struct trace_array_cpu *data;
@@ -917,6 +918,37 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
 	ftrace_preempt_enable(resched);
 }
 
+static void
+function_trace_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = &global_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+	int pc;
+
+	if (unlikely(!ftrace_function_enabled))
+		return;
+
+	/*
+	 * Need to use raw, since this must be called before the
+	 * recursive protection is performed.
+	 */
+	raw_local_irq_save(flags);
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+
+	if (likely(disabled == 1)) {
+		pc = preempt_count();
+		trace_function(tr, data, ip, parent_ip, flags, pc);
+	}
+
+	atomic_dec(&data->disabled);
+	raw_local_irq_restore(flags);
+}
+
 static struct ftrace_ops trace_ops __read_mostly =
 {
 	.func = function_trace_call,
@@ -925,6 +957,12 @@ static struct ftrace_ops trace_ops __read_mostly =
 void tracing_start_function_trace(void)
 {
 	ftrace_function_enabled = 0;
+
+	if (trace_flags & TRACE_ITER_PREEMPTONLY)
+		trace_ops.func = function_trace_call_preempt_only;
+	else
+		trace_ops.func = function_trace_call;
+
 	register_ftrace_function(&trace_ops);
 	if (tracer_enabled)
 		ftrace_function_enabled = 1;

trunk/kernel/trace/trace.h

@@ -415,6 +415,7 @@ enum trace_iterator_flags {
 	TRACE_ITER_STACKTRACE		= 0x100,
 	TRACE_ITER_SCHED_TREE		= 0x200,
 	TRACE_ITER_PRINTK		= 0x400,
+	TRACE_ITER_PREEMPTONLY		= 0x800,
 };
 
 extern struct tracer nop_trace;