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>

arch/x86/kernel/ftrace.c

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index f98c407..1b43086 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -476,7 +476,10 @@
 				&return_to_handler;
 
 	/* Nmi's are currently unsupported */
-	if (atomic_read(&in_nmi))
+	if (unlikely(atomic_read(&in_nmi)))
+		return;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		return;
 
 	/*