mm/mempolicy.c: use match_string() helper to simplify the code

match_string() returns the index of an array for a matching string, which
can be used intead of open coded implementation.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: zhong jiang <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: xiongzhongjiang

mm/mempolicy.c

@@ -2711,12 +2711,11 @@ static const char * const policy_modes[] =
 int mpol_parse_str(char *str, struct mempolicy **mpol)
 {
 	struct mempolicy *new = NULL;
-	unsigned short mode;
 	unsigned short mode_flags;
 	nodemask_t nodes;
 	char *nodelist = strchr(str, ':');
 	char *flags = strchr(str, '=');
-	int err = 1;
+	int err = 1, mode;
 
 	if (nodelist) {
 		/* NUL-terminate mode or flags string */
@@ -2731,12 +2730,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
 	if (flags)
 		*flags++ = '\0';	/* terminate mode string */
 
-	for (mode = 0; mode < MPOL_MAX; mode++) {
-		if (!strcmp(str, policy_modes[mode])) {
-			break;
-		}
-	}
-	if (mode >= MPOL_MAX)
+	mode = match_string(policy_modes, MPOL_MAX, str);
+	if (mode < 0)
 		goto out;
 
 	switch (mode) {