time: ntp: refactor and clean up ntp_update_offset()

Impact: cleanup, no functionality changed

- introduce the ntp_update_offset_fll() helper
- clean up the flow and variable naming

kernel/time/ntp.o:

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

md5:
   01f7b8e1a5472a3056f9e4ae84d46315  ntp.o.before.asm
   01f7b8e1a5472a3056f9e4ae84d46315  ntp.o.after.asm

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

1 files changed, 30 insertions, 14 deletions

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index f1abad738579..ee437e1445d1 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -103,10 +103,27 @@ static void ntp_update_frequency(void)
         tick_length_base         = new_base;
 }
 
+static inline s64 ntp_update_offset_fll(s64 freq_adj, s64 offset64, long secs)
+{
+        time_status &= ~STA_MODE;
+
+        if (secs < MINSEC)
+                return freq_adj;
+
+        if (!(time_status & STA_FLL) && (secs <= MAXSEC))
+                return freq_adj;
+
+        freq_adj += div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
+        time_status |= STA_MODE;
+
+        return freq_adj;
+}
+
 static void ntp_update_offset(long offset)
 {
-        long mtemp;
         s64 freq_adj;
+        s64 offset64;
+        long secs;
 
         if (!(time_status & STA_PLL))
                 return;
@@ -127,22 +144,21 @@ static void ntp_update_offset(long offset)
          */
         if (time_status & STA_FREQHOLD || time_reftime == 0)
                 time_reftime = xtime.tv_sec;
-        mtemp = xtime.tv_sec - time_reftime;
+
+        secs = xtime.tv_sec - time_reftime;
         time_reftime = xtime.tv_sec;
 
-        freq_adj = (s64)offset * mtemp;
-        freq_adj <<= NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant);
-        time_status &= ~STA_MODE;
-        if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
-                freq_adj += div_s64((s64)offset << (NTP_SCALE_SHIFT - SHIFT_FLL),
-                                    mtemp);
-                time_status |= STA_MODE;
-        }
-        freq_adj += time_freq;
-        freq_adj = min(freq_adj, MAXFREQ_SCALED);
-        time_freq = max(freq_adj, -MAXFREQ_SCALED);
+        offset64    = offset;
+        freq_adj    = (offset64 * secs) <<
+                        (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
+
+        freq_adj    = ntp_update_offset_fll(freq_adj, offset64, secs);
+
+        freq_adj    = min(freq_adj + time_freq, MAXFREQ_SCALED);
+
+        time_freq   = max(freq_adj, -MAXFREQ_SCALED);
 
-        time_offset = div_s64((s64)offset << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
+        time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
 }
 
 /**