[PATCH] nds32: ftrace: fix pointer comparison warning

[Randy Dunlap]

GCC 11.1.0 for nds32 (nds32le if it matters) complains:

../arch/nds32/kernel/ftrace.c: In function '_mcount':
../arch/nds32/kernel/ftrace.c:24:35: error: comparison of distinct pointer types lacks a cast [-Werror]
   24 |         if (ftrace_trace_function != ftrace_stub)
      |                                   ^~

Cast the second function (pointer) to (void *) to avoid the warning.

Fixes: a18082575c66 ("nds32/ftrace: Support static function tracer")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
To: Greentime Hu <green.hu@xxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Zong Li <zong@xxxxxxxxxxxxx>
Cc: Nick Hu <nickhu@xxxxxxxxxxxxx>
Cc: Vincent Chen <deanbo422@xxxxxxxxx>
---
 arch/nds32/kernel/ftrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-next-20211026.orig/arch/nds32/kernel/ftrace.c
+++ linux-next-20211026/arch/nds32/kernel/ftrace.c
@@ -21,7 +21,7 @@ noinline void _mcount(unsigned long pare
 
 	unsigned long ip = (unsigned long)__builtin_return_address(0);
 
-	if (ftrace_trace_function != ftrace_stub)
+	if (ftrace_trace_function != (void *)ftrace_stub)
 		ftrace_trace_function(ip - MCOUNT_INSN_SIZE, parent_ip,
 				      NULL, NULL);