| Message ID | 20231203193307.542794-25-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | bitops: add atomic find_bit() operations | expand |
diff --git a/drivers/isdn/mISDN/core.c b/drivers/isdn/mISDN/core.c index ab8513a7acd5..3f97db006cf3 100644 --- a/drivers/isdn/mISDN/core.c +++ b/drivers/isdn/mISDN/core.c @@ -197,14 +197,9 @@ get_mdevice_count(void) static int get_free_devid(void) { - u_int i; + u_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
get_free_devid() traverses each bit in device_ids in an open-coded loop. We can do it faster by using 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: ffs(); test_and_set_bit(). Signed-off-by: Yury Norov <yury.norov@gmail.com> --- drivers/isdn/mISDN/core.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)