Re: [PATCH v4 3/3] UBSAN: run-time undefined behavior sanity checker

[Andrew Morton]

On Fri, 4 Dec 2015 22:27:36 +0800 kbuild test robot <lkp@xxxxxxxxx> wrote:

> [auto build test WARNING on next-20151203]
> [cannot apply to tip/x86/core kbuild/rc-fixes v4.4-rc3 v4.4-rc2 v4.4-rc1 v4.4-rc3]
> 
> url:    https://github.com/0day-ci/linux/commits/Andrey-Ryabinin/UBSAN-run-time-undefined-behavior-sanity-checker/20151204-202547
> config: i386-allmodconfig (attached as .config)
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All warnings (new ones prefixed by >>):
> 
>    lib/ubsan.c: In function 'val_to_string':
> >> lib/ubsan.c:121:8: warning: unused variable 'val' [-Wunused-variable]
>      u_max val = get_unsigned_val(type, value);

I did this.

--- a/lib/ubsan.c~ubsan-run-time-undefined-behavior-sanity-checker-fix
+++ a/lib/ubsan.c
@@ -118,11 +118,11 @@ static u_max get_unsigned_val(struct typ
 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
 	unsigned long value)
 {
-	u_max val = get_unsigned_val(type, value);
-
 	if (type_is_int(type)) {
 		if (type_bit_width(type) == 128) {
 #ifdef CONFIG_ARCH_SUPPORTS_INT128
+			u_max val = get_unsigned_val(type, value);
+
 			scnprintf(str, size, "0x%08x%08x%08x%08x",
 				(u32)(val >> 96),
 				(u32)(val >> 64),

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