[PATCH] tracing: avoid build warning with HAVE_NOP_MCOUNT

[Vasily Gorbik]

Selecting HAVE_NOP_MCOUNT enables -mnop-mcount (if gcc supports it)
and sets CC_USING_NOP_MCOUNT. Reuse __is_defined (which is suitable for
testing CC_USING_* defines) to avoid conditional compilation and fix
the following gcc 9 warning on s390:

kernel/trace/ftrace.c:2514:1: warning: ‘ftrace_code_disable’ defined
but not used [-Wunused-function]

Signed-off-by: Vasily Gorbik <g...@linux.ibm.com>
---
 kernel/trace/ftrace.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a12aff849c04..e77a6c92620f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2935,14 +2935,13 @@ static int ftrace_update_code(struct module *mod, 
struct ftrace_page *new_pgs)
                        p = &pg->records[i];
                        p->flags = rec_flags;
 
-#ifndef CC_USING_NOP_MCOUNT
                        /*
                         * Do the initial record conversion from mcount jump
                         * to the NOP instructions.
                         */
-                       if (!ftrace_code_disable(mod, p))
+                       if (!__is_defined(CC_USING_NOP_MCOUNT) &&
+                           !ftrace_code_disable(mod, p))
                                break;
-#endif
 
                        update_cnt++;
                }
-- 
2.21.0