[PATCH 04/16 v2] tracing: Add disable_on_free option

[Steven Rostedt <rostedt@goodmis.org>]

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From: Steven Rostedt <srostedt@redhat.com>

Add a trace option to disable tracing on free. When this option is
set, a write into the free_buffer file will not only shrink the
ring buffer down to zero, but it will also disable tracing.

Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |    6 ++++--
 kernel/trace/trace.h |    1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9c557ae..42fdf3a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -425,6 +425,7 @@ static const char *trace_options[] = {
 	"graph-time",
 	"record-cmd",
 	"overwrite",
+	"disable_on_free",
 	NULL
 };
 
@@ -3518,8 +3519,9 @@ tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
 static int
 tracing_free_buffer_release(struct inode *inode, struct file *filp)
 {
-	/* disable tracing */
-	tracing_off();
+	/* disable tracing ? */
+	if (trace_flags & TRACE_ITER_STOP_ON_FREE)
+		tracing_off();
 	/* resize the ring buffer to 0 */
 	tracing_resize_ring_buffer(0);
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 229f859..742f545 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -609,6 +609,7 @@ enum trace_iterator_flags {
 	TRACE_ITER_GRAPH_TIME		= 0x80000,
 	TRACE_ITER_RECORD_CMD		= 0x100000,
 	TRACE_ITER_OVERWRITE		= 0x200000,
+	TRACE_ITER_STOP_ON_FREE		= 0x400000,
 };
 
 /*
-- 
1.7.4.4