mm/kasan/kasan.c: rename XXX_is_zero to XXX_is_nonzero

They return positive value, that is, true, if non-zero value is found.
Rename them to reduce confusion.

Link: http://lkml.kernel.org/r/20170516012350.GA16015@js1304-desktopSigned-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kasan/kasan.c

@@ -160,7 +160,7 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
 	return *shadow_addr;
 }
 
-static __always_inline unsigned long bytes_is_zero(const u8 *start,
+static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
 					size_t size)
 {
 	while (size) {
@@ -173,7 +173,7 @@ static __always_inline unsigned long bytes_is_zero(const u8 *start,
 	return 0;
 }
 
-static __always_inline unsigned long memory_is_zero(const void *start,
+static __always_inline unsigned long memory_is_nonzero(const void *start,
 						const void *end)
 {
 	unsigned int words;
@@ -181,11 +181,11 @@ static __always_inline unsigned long memory_is_zero(const void *start,
 	unsigned int prefix = (unsigned long)start % 8;
 
 	if (end - start <= 16)
-		return bytes_is_zero(start, end - start);
+		return bytes_is_nonzero(start, end - start);
 
 	if (prefix) {
 		prefix = 8 - prefix;
-		ret = bytes_is_zero(start, prefix);
+		ret = bytes_is_nonzero(start, prefix);
 		if (unlikely(ret))
 			return ret;
 		start += prefix;
@@ -194,12 +194,12 @@ static __always_inline unsigned long memory_is_zero(const void *start,
 	words = (end - start) / 8;
 	while (words) {
 		if (unlikely(*(u64 *)start))
-			return bytes_is_zero(start, 8);
+			return bytes_is_nonzero(start, 8);
 		start += 8;
 		words--;
 	}
 
-	return bytes_is_zero(start, (end - start) % 8);
+	return bytes_is_nonzero(start, (end - start) % 8);
 }
 
 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
@@ -207,7 +207,7 @@ static __always_inline bool memory_is_poisoned_n(unsigned long addr,
 {
 	unsigned long ret;
 
-	ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
+	ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
 			kasan_mem_to_shadow((void *)addr + size - 1) + 1);
 
 	if (unlikely(ret)) {