ntp: Read reference time only once

The reference time is required twice in ntp_update_offset(). It will not
change in the meantime as the calling code holds the timekeeper lock. Read
it only once and store it into a local variable.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20240911-devel-anna-maria-b4-timers-ptp-ntp-v1-6-2d52f4e13476@linutronix.de

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 905b0216b12dc4f2dad79b20664647d885c2e0a8..0bfd07de202a56540852b086e0429e47c3a4ec2e 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -283,9 +283,8 @@ static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
 
 static void ntp_update_offset(long offset)
 {
-       s64 freq_adj;
-       s64 offset64;
-       long secs;
+       s64 freq_adj, offset64;
+       long secs, real_secs;
 
        if (!(time_status & STA_PLL))
                return;
@@ -303,11 +302,12 @@ static void ntp_update_offset(long offset)
         * Select how the frequency is to be controlled
         * and in which mode (PLL or FLL).
         */
-       secs = (long)(__ktime_get_real_seconds() - time_reftime);
+       real_secs = __ktime_get_real_seconds();
+       secs = (long)(real_secs - time_reftime);
        if (unlikely(time_status & STA_FREQHOLD))
                secs = 0;
 
-       time_reftime = __ktime_get_real_seconds();
+       time_reftime = real_secs;
 
        offset64    = offset;
        freq_adj    = ntp_update_offset_fll(offset64, secs);