jump label: Tracepoint support for jump labels

Make use of the jump label infrastructure for tracepoints.

Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <a9ba2056e2c9cf332c3c300b577463ce66ff23a8.1284733808.git.jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 16 insertions, 3 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 103d1b61aacb..a4a90b6726ce 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -17,6 +17,7 @@
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/rcupdate.h>
+#include <linux/jump_label.h>
 
 struct module;
 struct tracepoint;
@@ -145,7 +146,9 @@ static inline void tracepoint_update_probe_range(struct tracepoint *begin,
         extern struct tracepoint __tracepoint_##name;                   \
         static inline void trace_##name(proto)                          \
         {                                                               \
-                if (unlikely(__tracepoint_##name.state))                \
+                JUMP_LABEL(&__tracepoint_##name.state, do_trace);       \
+                return;                                                 \
+do_trace:                                                               \
                         __DO_TRACE(&__tracepoint_##name,                \
                                 TP_PROTO(data_proto),                   \
                                 TP_ARGS(data_args));                    \
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index c77f3eceea25..d6073a50a6ca 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -25,6 +25,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/jump_label.h>
 
 extern struct tracepoint __start___tracepoints[];
 extern struct tracepoint __stop___tracepoints[];
@@ -263,7 +264,13 @@ static void set_tracepoint(struct tracepoint_entry **entry,
          * is used.
          */
         rcu_assign_pointer(elem->funcs, (*entry)->funcs);
-        elem->state = active;
+        if (!elem->state && active) {
+                enable_jump_label(&elem->state);
+                elem->state = active;
+        } else if (elem->state && !active) {
+                disable_jump_label(&elem->state);
+                elem->state = active;
+        }
 }
 
 /*
@@ -277,7 +284,10 @@ static void disable_tracepoint(struct tracepoint *elem)
         if (elem->unregfunc && elem->state)
                 elem->unregfunc();
 
-        elem->state = 0;
+        if (elem->state) {
+                disable_jump_label(&elem->state);
+                elem->state = 0;
+        }
         rcu_assign_pointer(elem->funcs, NULL);
 }