tracing: avoid build warning with HAVE_NOP_MCOUNT

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]

Link: http://lkml.kernel.org/r/patch.git-1a82d13f33ac.your-ad-here.call-01559732716-ext-6629@work.hours

Fixes: 2f4df0017baed ("tracing: Add -mcount-nop option support")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files 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++;
                 }