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authorSteven Rostedt <rostedt@goodmis.org>2008-07-15 09:53:37 -0400
committerIngo Molnar <mingo@elte.hu>2008-07-18 18:57:34 +0200
commit1e01cb0c6ff7e9ddb6547551794c6aa82785a7cb (patch)
tree791ecc834a169f6e3d7322a0c285dd95e9cd0c31 /kernel/trace
parente59494f441c834ca7aaa0e6fa6678ddbd3d72743 (diff)
downloadlinux-1e01cb0c6ff7e9ddb6547551794c6aa82785a7cb.tar.gz
ftrace: only trace preempt off with preempt tracer
When PREEMPT_TRACER and IRQSOFF_TRACER are both configured and irqsoff
tracer is running, the preempt_off sections might also be traced.

Thanks to Andrew Morton for pointing out my mistake of spin_lock disabling
interrupts while he was reviewing ftrace.txt. Seems that my example I used
actually hit this bug.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_irqsoff.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 421d6fe3650e..b1e4a89b08eb 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -337,12 +337,14 @@ EXPORT_SYMBOL(trace_hardirqs_off_caller);
 #ifdef CONFIG_PREEMPT_TRACER
 void trace_preempt_on(unsigned long a0, unsigned long a1)
 {
-	stop_critical_timing(a0, a1);
+	if (preempt_trace())
+		stop_critical_timing(a0, a1);
 }
 
 void trace_preempt_off(unsigned long a0, unsigned long a1)
 {
-	start_critical_timing(a0, a1);
+	if (preempt_trace())
+		start_critical_timing(a0, a1);
 }
 #endif /* CONFIG_PREEMPT_TRACER */