[for-next][PATCH 4/4] tracing: Add the constant count for branch tracer

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

The unlikely/likely branch profiler now gets called even if the if statement
is a constant (always goes in one direction without a compare). Add a value
to denote this in the likely/unlikely tracer as well.

Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_branch.c  | 17 +++++++++--------
 kernel/trace/trace_entries.h |  6 ++++--
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index fd483d74f8e1..4d8fdf3184dc 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -27,7 +27,7 @@ static DEFINE_MUTEX(branch_tracing_mutex);
 static struct trace_array *branch_tracer;
 
 static void
-probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
+probe_likely_condition(struct ftrace_likely_data *f, int val, int expect)
 {
 	struct trace_event_call *call = &event_branch;
 	struct trace_array *tr = branch_tracer;
@@ -68,16 +68,17 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 	entry	= ring_buffer_event_data(event);
 
 	/* Strip off the path, only save the file */
-	p = f->file + strlen(f->file);
-	while (p >= f->file && *p != '/')
+	p = f->data.file + strlen(f->data.file);
+	while (p >= f->data.file && *p != '/')
 		p--;
 	p++;
 
-	strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
+	strncpy(entry->func, f->data.func, TRACE_FUNC_SIZE);
 	strncpy(entry->file, p, TRACE_FILE_SIZE);
 	entry->func[TRACE_FUNC_SIZE] = 0;
 	entry->file[TRACE_FILE_SIZE] = 0;
-	entry->line = f->line;
+	entry->constant = f->constant;
+	entry->line = f->data.line;
 	entry->correct = val == expect;
 
 	if (!call_filter_check_discard(call, entry, buffer, event))
@@ -89,7 +90,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 }
 
 static inline
-void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
+void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)
 {
 	if (!branch_tracing_enabled)
 		return;
@@ -195,7 +196,7 @@ core_initcall(init_branch_tracer);
 
 #else
 static inline
-void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
+void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)
 {
 }
 #endif /* CONFIG_BRANCH_TRACER */
@@ -214,7 +215,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	 * conditions that the recursive nightmare that exists is too
 	 * much to try to get working. At least for now.
 	 */
-	trace_likely_condition(&f->data, val, expect);
+	trace_likely_condition(f, val, expect);
 
 	/* FIXME: Make this atomic! */
 	if (val == expect)
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index eb7396b7e7c3..c203ac4df791 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -328,11 +328,13 @@ FTRACE_ENTRY(branch, trace_branch,
 		__array(	char,		func,	TRACE_FUNC_SIZE+1	)
 		__array(	char,		file,	TRACE_FILE_SIZE+1	)
 		__field(	char,		correct				)
+		__field(	char,		constant			)
 	),
 
-	F_printk("%u:%s:%s (%u)",
+	F_printk("%u:%s:%s (%u)%s",
 		 __entry->line,
-		 __entry->func, __entry->file, __entry->correct),
+		 __entry->func, __entry->file, __entry->correct,
+		 __entry->constant ? " CONSTANT" : ""),
 
 	FILTER_OTHER
 );
-- 
2.10.2