tracing: Add disable_on_free option

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>

2 files changed, 5 insertions, 2 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9c557ae6a21e..42fdf3adff31 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 229f8591f61d..742f545ae185 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,
 };
 
 /*