[PATCH v4 25/40] mISDN: optimize get_free_devid()

[Yury Norov <yury.norov@gmail.com>]

get_free_devid() traverses each bit in device_ids in an open-coded loop.
Simplify it by using the dedicated find_and_set_bit().

It makes the whole function a nice one-liner. And because MAX_DEVICE_ID
is a small constant-time value (63), on 64-bit platforms find_and_set_bit()
call will be optimized to:

	test_and_set_bit(ffs());

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 drivers/isdn/mISDN/core.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/isdn/mISDN/core.c b/drivers/isdn/mISDN/core.c
index ab8513a7acd5..d499b193529a 100644
--- a/drivers/isdn/mISDN/core.c
+++ b/drivers/isdn/mISDN/core.c
@@ -3,6 +3,7 @@
  * Copyright 2008  by Karsten Keil <kkeil@novell.com>
  */
 
+#include <linux/find_atomic.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/stddef.h>
@@ -197,14 +198,9 @@ get_mdevice_count(void)
 static int
 get_free_devid(void)
 {
-	u_int	i;
+	int i = find_and_set_bit((u_long *)&device_ids, MAX_DEVICE_ID + 1);
 
-	for (i = 0; i <= MAX_DEVICE_ID; i++)
-		if (!test_and_set_bit(i, (u_long *)&device_ids))
-			break;
-	if (i > MAX_DEVICE_ID)
-		return -EBUSY;
-	return i;
+	return i <= MAX_DEVICE_ID ? i : -EBUSY;
 }
 
 int
-- 
2.43.0