lib/string.c: introduce memchr_inv()
memchr_inv() is mainly used to check whether the whole buffer is filled
with just a specified byte.
The function name and prototype are stolen from logfs and the
implementation is from SLUB.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: Joern Engel <joern@logfs.org>
Cc: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slub.c b/mm/slub.c
index 95215aa..7d2a996 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -655,49 +655,6 @@
memset(p + s->objsize, val, s->inuse - s->objsize);
}
-static u8 *check_bytes8(u8 *start, u8 value, unsigned int bytes)
-{
- while (bytes) {
- if (*start != value)
- return start;
- start++;
- bytes--;
- }
- return NULL;
-}
-
-static u8 *check_bytes(u8 *start, u8 value, unsigned int bytes)
-{
- u64 value64;
- unsigned int words, prefix;
-
- if (bytes <= 16)
- return check_bytes8(start, value, bytes);
-
- value64 = value | value << 8 | value << 16 | value << 24;
- value64 = (value64 & 0xffffffff) | value64 << 32;
- prefix = 8 - ((unsigned long)start) % 8;
-
- if (prefix) {
- u8 *r = check_bytes8(start, value, prefix);
- if (r)
- return r;
- start += prefix;
- bytes -= prefix;
- }
-
- words = bytes / 8;
-
- while (words) {
- if (*(u64 *)start != value64)
- return check_bytes8(start, value, 8);
- start += 8;
- words--;
- }
-
- return check_bytes8(start, value, bytes % 8);
-}
-
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
@@ -712,7 +669,7 @@
u8 *fault;
u8 *end;
- fault = check_bytes(start, value, bytes);
+ fault = memchr_inv(start, value, bytes);
if (!fault)
return 1;
@@ -805,7 +762,7 @@
if (!remainder)
return 1;
- fault = check_bytes(end - remainder, POISON_INUSE, remainder);
+ fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)