time: ntp: micro-optimize ntp_update_offset()

Impact: cleanup, no functionality changed

The time_reftime update in ntp_update_offset() to xtime.tv_sec
is a convoluted way of saying that we want to freeze the frequency
and want the 'secs' delta to be 0. Also make this branch unlikely.

This shaves off 8 bytes from the code size:

   text	   data	    bss	    dec	    hex	filename
   2504	    114	    136	   2754	    ac2	ntp.o.before
   2496	    114	    136	   2746	    aba	ntp.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 5202dde2f0af59d890d0ae086df77cb63c34776f..580a3502869341c42ad03301479da22a420fbd63 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -141,10 +141,10 @@ static void ntp_update_offset(long offset)
         * Select how the frequency is to be controlled
         * and in which mode (PLL or FLL).
         */
-       if (time_status & STA_FREQHOLD || time_reftime == 0)
-               time_reftime = xtime.tv_sec;
-
        secs = xtime.tv_sec - time_reftime;
+       if (unlikely(time_status & STA_FREQHOLD || time_reftime == 0))
+               secs = 0;
+
        time_reftime = xtime.tv_sec;
 
        offset64    = offset;