tracing: Move tracepoint callbacks from declaration to definition

It's not strictly correct for the tracepoint reg/unreg callbacks to
occur when a client is hooking up, because the actual tracepoint may not
be present yet.  This happens to be fine for syscall, since that's in
the core kernel, but it would cause problems for tracepoints defined in
a module that hasn't been loaded yet.  It also means the reg/unreg has
to be EXPORTed for any modules to use the tracepoint (as in SystemTap).

This patch removes DECLARE_TRACE_WITH_CALLBACK, and instead introduces
DEFINE_TRACE_FN which stores the callbacks in struct tracepoint.  The
callbacks are used now when the active state of the tracepoint changes
in set_tracepoint & disable_tracepoint.

This also introduces TRACE_EVENT_FN, so ftrace events can also provide
registration callbacks if needed.

Signed-off-by: Josh Stone <jistone@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
LKML-Reference: <1251150194-1713-4-git-send-email-jistone@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

3 files changed, 18 insertions, 8 deletions

diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
index f7a7ae1e8f90..2a969850736d 100644
--- a/include/trace/define_trace.h
+++ b/include/trace/define_trace.h
@@ -26,6 +26,11 @@
 #define TRACE_EVENT(name, proto, args, tstruct, assign, print)  \
         DEFINE_TRACE(name)
 
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,              \
+                assign, print, reg, unreg)                      \
+        DEFINE_TRACE_FN(name, reg, unreg)
+
 #undef DECLARE_TRACE
 #define DECLARE_TRACE(name, proto, args)        \
         DEFINE_TRACE(name)
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 127400255e4c..3a0b44bdabf7 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -42,6 +42,15 @@
         };                                                      \
         static struct ftrace_event_call event_##name
 
+/* Callbacks are meaningless to ftrace. */
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,              \
+                assign, print, reg, unreg)                      \
+        TRACE_EVENT(name, TP_PROTO(proto), TP_ARGS(args),       \
+                TP_STRUCT__entry(tstruct),                      \
+                TP_fast_assign(assign),                         \
+                TP_printk(print))
+
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 
 
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 5dcb7e3a544c..4e1943001854 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -13,18 +13,14 @@
 extern void syscall_regfunc(void);
 extern void syscall_unregfunc(void);
 
-DECLARE_TRACE_WITH_CALLBACK(syscall_enter,
+DECLARE_TRACE(syscall_enter,
         TP_PROTO(struct pt_regs *regs, long id),
-        TP_ARGS(regs, id),
-        syscall_regfunc,
-        syscall_unregfunc
+        TP_ARGS(regs, id)
 );
 
-DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
+DECLARE_TRACE(syscall_exit,
         TP_PROTO(struct pt_regs *regs, long ret),
-        TP_ARGS(regs, ret),
-        syscall_regfunc,
-        syscall_unregfunc
+        TP_ARGS(regs, ret)
 );
 
 #endif