tracing: Make syscall tracepoints conditional

The syscall enter/exit tracepoints are only supported on archs that
HAVE_SYSCALL_TRACEPOINTS, so the declarations should be #ifdef'ed.
Also, the definition of syscall_regfunc and syscall_unregfunc should
depend on this same config, rather than the ftrace-specific one.

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>
LKML-Reference: <1251150194-1713-3-git-send-email-jistone@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

include/trace/syscall.h

@@ -8,6 +8,8 @@
 #include <asm/ptrace.h>
 
 
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
+
 extern void syscall_regfunc(void);
 extern void syscall_unregfunc(void);
 
@@ -25,6 +27,8 @@ DECLARE_TRACE_WITH_CALLBACK(syscall_exit,
 	syscall_unregfunc
 );
 
+#endif
+
 /*
  * A syscall entry in the ftrace syscalls array.
  *

kernel/tracepoint.c

@@ -576,7 +576,7 @@ __initcall(init_tracepoints);
 
 #endif /* CONFIG_MODULES */
 
-#ifdef CONFIG_FTRACE_SYSCALLS
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
 
 static DEFINE_MUTEX(regfunc_mutex);
 static int sys_tracepoint_refcount;