commit 380c4b1411ccd6885f92b2c8ceb08433a720f44e
author Frederic Weisbecker <fweisbec@gmail.com> Sat Dec 06 03:43:41 2008 +0100
committer Ingo Molnar <mingo@elte.hu> Mon Dec 08 15:11:45 2008 +0100
tree f3b571e1caff2de3e6b4cace87c2b1ec332667d7
parent 8e1b82e0866befaa0b2920be296c6e4c3fc7f422

tracing/function-graph-tracer: append the tracing_graph_flag

Impact: Provide a way to pause the function graph tracer

As suggested by Steven Rostedt, the previous patch that prevented from
spinlock function tracing shouldn't use the raw_spinlock to fix it.
It's much better to follow lockdep with normal spinlock, so this patch
adds a new flag for each task to make the function graph tracer able
to be paused. We also can send an ftrace_printk whithout worrying of
the irrelevant traced spinlock during insertion.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/ftrace.h

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 449fa8e..11cac81 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -401,6 +401,16 @@
 {
 	return t->curr_ret_stack;
 }
+
+static inline void pause_graph_tracing(void)
+{
+	atomic_inc(&current->tracing_graph_pause);
+}
+
+static inline void unpause_graph_tracing(void)
+{
+	atomic_dec(&current->tracing_graph_pause);
+}
 #else
 
 #define __notrace_funcgraph
@@ -412,6 +422,9 @@
 {
 	return -1;
 }
+
+static inline void pause_graph_tracing(void) { }
+static inline void unpause_graph_tracing(void) { }
 #endif
 
 #ifdef CONFIG_TRACING