markers: auto enable tracepoints (new API : trace_mark_tp())

Impact: new API

Add a new API trace_mark_tp(), which declares a marker within a
tracepoint probe. When the marker is activated, the tracepoint is
automatically enabled.

No branch test is used at the marker site, because it would be a
duplicate of the branch already present in the tracepoint.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 44 insertions, 1 deletions

diff --git a/include/linux/marker.h b/include/linux/marker.h
index 05ec0df3708..57a307018ce 100644
--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -49,6 +49,8 @@ struct marker {
 	void (*call)(const struct marker *mdata, void *call_private, ...);
 	struct marker_probe_closure single;
 	struct marker_probe_closure *multi;
+	const char *tp_name;	/* Optional tracepoint name */
+	void *tp_cb;		/* Optional tracepoint callback */
 } __attribute__((aligned(8)));
 
 #ifdef CONFIG_MARKERS
@@ -73,7 +75,7 @@ struct marker {
 		__attribute__((section("__markers"), aligned(8))) =	\
 		{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)],	\
 		0, 0, marker_probe_cb,					\
-		{ __mark_empty_function, NULL}, NULL };			\
+		{ __mark_empty_function, NULL}, NULL, NULL, NULL };	\
 		__mark_check_format(format, ## args);			\
 		if (unlikely(__mark_##name.state)) {			\
 			(*__mark_##name.call)				\
@@ -81,11 +83,38 @@ struct marker {
 		}							\
 	} while (0)
 
+#define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
+	do {								\
+		void __check_tp_type(void)				\
+		{							\
+			register_trace_##tp_name(tp_cb);		\
+		}							\
+		static const char __mstrtab_##name[]			\
+		__attribute__((section("__markers_strings")))		\
+		= #name "\0" format;					\
+		static struct marker __mark_##name			\
+		__attribute__((section("__markers"), aligned(8))) =	\
+		{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)],	\
+		0, 0, marker_probe_cb,					\
+		{ __mark_empty_function, NULL}, NULL, #tp_name, tp_cb };\
+		__mark_check_format(format, ## args);			\
+		(*__mark_##name.call)(&__mark_##name, call_private,	\
+					## args);			\
+	} while (0)
+
 extern void marker_update_probe_range(struct marker *begin,
 	struct marker *end);
 #else /* !CONFIG_MARKERS */
 #define __trace_mark(generic, name, call_private, format, args...) \
 		__mark_check_format(format, ## args)
+#define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
+	do {								\
+		void __check_tp_type(void)				\
+		{							\
+			register_trace_##tp_name(tp_cb);		\
+		}							\
+		__mark_check_format(format, ## args);			\
+	} while (0)
 static inline void marker_update_probe_range(struct marker *begin,
 	struct marker *end)
 { }
@@ -118,6 +147,20 @@ static inline void marker_update_probe_range(struct marker *begin,
 	__trace_mark(1, name, NULL, format, ## args)
 
 /**
+ * trace_mark_tp - Marker in a tracepoint callback
+ * @name: marker name, not quoted.
+ * @tp_name: tracepoint name, not quoted.
+ * @tp_cb: tracepoint callback. Should have an associated global symbol so it
+ *         is not optimized away by the compiler (should not be static).
+ * @format: format string
+ * @args...: variable argument list
+ *
+ * Places a marker in a tracepoint callback.
+ */
+#define trace_mark_tp(name, tp_name, tp_cb, format, args...)	\
+	__trace_mark_tp(name, NULL, tp_name, tp_cb, format, ## args)
+
+/**
  * MARK_NOARGS - Format string for a marker with no argument.
  */
 #define MARK_NOARGS " "