commit b8de7bd168fa54d059b16d3057b2f8a32cc5bdc3
author Steven Rostedt <srostedt@redhat.com> Mon Aug 31 22:32:27 2009 -0400
committer Steven Rostedt <rostedt@goodmis.org> Fri Sep 04 11:52:24 2009 -0400
tree 3455ec59050f7f6d466a8c08275567079914d1b1
parent 8248ac052dfd1eb41819fbc0ca5c7a1667e7e70c

tracing: disable update max tracer while reading trace

When reading the tracer from the trace file, updating the max latency
may corrupt the output. This patch disables the tracing of the max
latency while reading the trace file.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index df2c9f7..e521f1e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -263,6 +263,9 @@
 	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
 	TRACE_ITER_GRAPH_TIME;
 
+static int trace_stop_count;
+static DEFINE_SPINLOCK(tracing_start_lock);
+
 /**
  * trace_wake_up - wake up tasks waiting for trace input
  *
@@ -442,6 +445,9 @@
 {
 	struct ring_buffer *buf = tr->buffer;
 
+	if (trace_stop_count)
+		return;
+
 	WARN_ON_ONCE(!irqs_disabled());
 	__raw_spin_lock(&ftrace_max_lock);
 
@@ -469,6 +475,9 @@
 {
 	int ret;
 
+	if (trace_stop_count)
+		return;
+
 	WARN_ON_ONCE(!irqs_disabled());
 	__raw_spin_lock(&ftrace_max_lock);
 
@@ -685,9 +694,6 @@
 	cmdline_idx = 0;
 }
 
-static int trace_stop_count;
-static DEFINE_SPINLOCK(tracing_start_lock);
-
 /**
  * ftrace_off_permanent - disable all ftrace code permanently
  *