tracing/function-graph-tracer: handle the leaf functions from trace_pipe

When one cats the trace file, the leaf functions are printed without brackets:

 function();

whereas in the trace_pipe file we'll see the following:

 function() {
 }

This is because the ring_buffer handling is not the same between those two files.
On the trace file, when an entry is printed, the iterator advanced and then we can
check the next entry.

There is no iterator with trace_pipe, the current entry to print has been peeked
and not consumed. So checking the next entry will still return the current one while
we don't consume it.

This patch introduces a new value for the output callbacks to ask the tracing
core to not consume the current entry after printing it.

We need it because we will have to consume the current entry ourself to check
the next one.

Now the trace_pipe is able to handle well the leaf functions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 3 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1ecfb9d2b365..7b0518adf6d7 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -63,13 +63,13 @@ struct ftrace_entry {
 
 /* Function call entry */
 struct ftrace_graph_ent_entry {
-        struct trace_entry                      ent;
+        struct trace_entry              ent;
         struct ftrace_graph_ent         graph_ent;
 };
 
 /* Function return entry */
 struct ftrace_graph_ret_entry {
-        struct trace_entry                      ent;
+        struct trace_entry              ent;
         struct ftrace_graph_ret         ret;
 };
 extern struct tracer boot_tracer;
@@ -309,7 +309,8 @@ extern void __ftrace_bad_type(void);
 enum print_line_t {
         TRACE_TYPE_PARTIAL_LINE = 0,    /* Retry after flushing the seq */
         TRACE_TYPE_HANDLED      = 1,
-        TRACE_TYPE_UNHANDLED    = 2     /* Relay to other output functions */
+        TRACE_TYPE_UNHANDLED    = 2,    /* Relay to other output functions */
+        TRACE_TYPE_NO_CONSUME   = 3     /* Handled but ask to not consume */
 };