mtd: nand_bbt: use string library

Some nand_bbt code can be shortened by using memcmp() and memchr_inv().
As an added bonus, there is a possible performance benefit.

Borrowed some code from Akinobu Mita.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index e23115b..f5839f0 100644 (file)
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -68,6 +68,7 @@
 #include <linux/delay.h>
 #include <linux/vmalloc.h>
 #include <linux/export.h>
+#include <linux/string.h>
 
 static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
 {
@@ -89,19 +90,16 @@ static int check_pattern_no_oob(uint8_t *buf, struct nand_bbt_descr *td)
  */
 static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_descr *td)
 {
-       int i, end = 0;
+       int end = 0;
        uint8_t *p = buf;
 
        if (td->options & NAND_BBT_NO_OOB)
                return check_pattern_no_oob(buf, td);
 
        end = paglen + td->offs;
-       if (td->options & NAND_BBT_SCANEMPTY) {
-               for (i = 0; i < end; i++) {
-                       if (p[i] != 0xff)
-                               return -1;
-               }
-       }
+       if (td->options & NAND_BBT_SCANEMPTY)
+               if (memchr_inv(p, 0xff, end))
+                       return -1;
        p += end;
 
        /* Compare the pattern */
@@ -111,10 +109,8 @@ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_desc
        if (td->options & NAND_BBT_SCANEMPTY) {
                p += td->len;
                end += td->len;
-               for (i = end; i < len; i++) {
-                       if (*p++ != 0xff)
-                               return -1;
-               }
+               if (memchr_inv(p, 0xff, len - end))
+                       return -1;
        }
        return 0;
 }
@@ -130,14 +126,9 @@ static int check_pattern(uint8_t *buf, int len, int paglen, struct nand_bbt_desc
  */
 static int check_short_pattern(uint8_t *buf, struct nand_bbt_descr *td)
 {
-       int i;
-       uint8_t *p = buf;
-
        /* Compare the pattern */
-       for (i = 0; i < td->len; i++) {
-               if (p[td->offs + i] != td->pattern[i])
-                       return -1;
-       }
+       if (memcmp(buf + td->offs, td->pattern, td->len))
+               return -1;
        return 0;
 }