markers: create DEFINE_MARKER and GET_MARKER (new API)

Impact: new API.

Allow markers to be used only for declaration, without function call
associated. Useful to create specialized probes.

The problem we had is that two function calls were required when one
wanted to put a marker in a tracepoint probe. Now the marker can be used
simply for trace data type declaration, leaving the trace write work
within the tracepoint probe without any additional function call.

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

1 files changed, 23 insertions, 16 deletions

diff --git a/include/linux/marker.h b/include/linux/marker.h
index 57a307018ceb..34c14bc957f5 100644
--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -55,6 +55,22 @@ struct marker {
 
 #ifdef CONFIG_MARKERS
 
+#define _DEFINE_MARKER(name, tp_name_str, tp_cb, format)                \
+                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_str, tp_cb }
+
+#define DEFINE_MARKER(name, format)                                     \
+                _DEFINE_MARKER(name, NULL, NULL, format)
+
+#define DEFINE_MARKER_TP(name, tp_name, tp_cb, format)                  \
+                _DEFINE_MARKER(name, #tp_name, tp_cb, format)
+
 /*
  * Note : the empty asm volatile with read constraint is used here instead of a
  * "used" attribute to fix a gcc 4.1.x bug.
@@ -68,14 +84,7 @@ struct marker {
  */
 #define __trace_mark(generic, name, call_private, format, args...)      \
         do {                                                            \
-                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, NULL, NULL };     \
+                DEFINE_MARKER(name, format);                            \
                 __mark_check_format(format, ## args);                   \
                 if (unlikely(__mark_##name.state)) {                    \
                         (*__mark_##name.call)                           \
@@ -89,14 +98,7 @@ struct marker {
                 {                                                       \
                         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 };\
+                DEFINE_MARKER_TP(name, tp_name, tp_cb, format);         \
                 __mark_check_format(format, ## args);                   \
                 (*__mark_##name.call)(&__mark_##name, call_private,     \
                                         ## args);                       \
@@ -104,7 +106,11 @@ struct marker {
 
 extern void marker_update_probe_range(struct marker *begin,
         struct marker *end);
+
+#define GET_MARKER(name)        (__mark_##name)
+
 #else /* !CONFIG_MARKERS */
+#define DEFINE_MARKER(name, tp_name, tp_cb, format)
 #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...) \
@@ -118,6 +124,7 @@ extern void marker_update_probe_range(struct marker *begin,
 static inline void marker_update_probe_range(struct marker *begin,
         struct marker *end)
 { }
+#define GET_MARKER(name)
 #endif /* CONFIG_MARKERS */
 
 /**